67P/Churyumov-Gerasimenko. A Single Body That’s Been Stretched- Part 25

TELL-TALE LINES ACROSS ANUKET: 1-KM-LONG LINKS BETWEEN THE MATCHES 
 
Key:
Orange and dark green lines- these link their respective head and body matches.

Yellow line- this links the yellow head and body matches. However there is no line continuing across the dust of Hapi to the yellow-dotted body match. This last stretch of the line can be inferred from protrusions along the yellow line in the neck, whose shapes match to shapes within both the head and body matches.

Mauve- this line also doesn’t stretch across Hapi to the mauve body match. It can be inferred in exactly the same way as for the yellow line.

Other colours follow the head rim, the matching body shear line, from which the head rim sheared away under ‘centrifugal’ force, and various blue-dotted ridges that match from head to body. 

Photo 2- Header photo with the four lines left unannotated. 

 

BACKGROUND

This post is the fourth section of a sub series leading up to proof that the head lobe of 67P stretched prior to shearing from the body. Each section in the sub series can be considered as a post in its own right with its own intrinsic interest and contribution to stretch theory in general. However, certain points in each post are collated at the end in a ‘take home message’ to be borne in mind for proving head stretch before shearing. 

This post is in fact more important than the sub series theme because it provides unequivocal proof that the neck stretched after shearing, and it does so using visual evidence embedded in the neck, not matches. Head lobe stretch before shearing is a secondary issue, however far-reaching the implications may be.

The lines in the header photo will also be shown to be a visual record of head lobe rotation.  

The take home message will come at the end of the post but it’s derived from the fact that there are tell-tale lines visible today in the neck at Anuket that link all four of the coloured matches in Part 24. In two cases, the line runs from the head match point to the body match point. In the other two cases, the missing last stretch can be inferred. 

As usual, scenarios are laid out here as fact to save on qualifying every statement. In this post in particular, some of the exact movements of material out of Hapi and the sequence of those movements is not going to be exactly as it happened but the scenario is based on good evidence and would have played out in a broadly similar way. As for making the usual blanket qualification about the possibility of stretch theory itself being wrong, this is becoming more and more academic, almost to the point of being misleading. The possibility of stretch theory being wrong is now so very remote and this post makes it remoter still. 

Apologies for some apparently repetitive statements. Although the general theme of this post is easy to see, describing some of the ‘mini matches’ within the matching features is a minefield of potential ambiguity, even with the photos. Hence appearing to lead by the hand at every stage when these are described.

A NOTE ABOUT THE ESA REGIONS AND THE UNOFFICIAL REGIONS IN THIS BLOG. 

Before starting, it would be as well to show the ESA map of all the regions because at least half a dozen of them are mentioned in this post. 

PHOTO 3- Regions.  

 

In Part 24 we concentrated on the four matches between Serqet and Seth. The matches were given colours: mauve, yellow, orange and dark green, looking from left to right across the upright duck shape (all references to left, right, up and down in this post refer to the upright duck). The two outside matches, mauve and dark green were at either end of the base of the red triangle (Parts 21-24). That triangle encloses a group of relatively undisturbed craters. The two inner matches, yellow and orange, were spaced evenly between the two flanking ones. 

The dark green body match looks as if it adjoins Anubis and not Seth. It is true that it adjoined the Anubis missing slab (Part 23) and should therefore be on the Anuket/Anubis border. However, ESA continued the Seth region border round the neck in a very thin line so as to include the rocky outcrop that is the dark green match. That’s because it’s rocky like Seth whereas Anuket and Anubis are smooth areas either side of it. 

This is why the name ‘Seth’ hasn’t been used much in the sub series. Seth covers four areas of differing morphology and evolution that are all named separately in this blog: missing slab A, the slab A extension, the red triangle of undisturbed craters and a tiny area that’s theoretically a single point: the Anuket/Anubis/Seth border that incorporates the dark green match. This is why the green match has also been called the ‘three-way junction’. It doesn’t just happen to sit at the three-way meeting point of ESA’s regions by chance. It sits at the unique spot where the head lobe, body lobe and missing Anubis slab all kissed each other before they departed company so dramatically. ESA’s region borders are delineating areas of different morphology and this blog is explaining the mechanisms that gave rise to those differing morphologies. 

THE LINES IN THE NECK AT ANUKET

Despite paying much attention to the corresponding features on the coloured matches in Part 24, such as ridges, dips and striations, one significant link between these matches wasn’t mentioned: all four have long lines running from their head rim matches to the base of the neck. And the lines that run from the green and orange head matches even extend past the base of the neck, across the dust of Hapi, to join their corresponding matches on the body. 

Let’s label the lines according to the match colour they are associated with. There are no lines running the whole length of the neck at Anuket other than these four that are associated with the matches. The yellow and mauve lines sport a few apparently associated offshoots that run parallel. For both lines, these diminish and become one (for each colour) towards the bottom of the neck. The orange line is the least solid of the four because it has several horizontal offshoots in the middle that interrupt the vertical flow. However, viewing it from a distance, its average twists and turns mirror those of the other three. The horizontal peregrinations peter out two-thirds of the way down the neck and become one obvious line for the last third and across Hapi. 

The orange line stops at the end of the orange anchor point that was embedded in the body and inside the shear line. This anchor is a double-line imprinted on a fracture plane in Hapi and it mirrors the double ridge in the head above, curving round to the left when it meets the inner edge of the fracture plane- just as it does on the head (Part 24 and photo 25 in this part). In this sense, the orange line doesn’t quite reach the ‘official’ orange dot for the body match on the shear line itself. However, it kisses part of the orange anchor formation and that is a match in its own right as just described above. 

Photos 4/5- Orange and green lines kissing their body match points. Some annotations in this post are so fine that they are almost invisible or obliterating what they’re annotating. So the original is placed underneath for reference. In each case, the key is below both photos. 

   

Large orange dot- orange body match.

Large green dot- green body match.
Small orange dots- orange line running down from orange head lobe match. 

Small green dots- green line from green head match. 

Blue- double imprint that matches a double ridge on the head. 

Yellow- shear line.

Medium size dark green- continuation of shear line across the front of the green anchor formation. 

So when the orange line met the imprinted anchor point it had gone as far as it could physically go. Material was swept from the very last stretch, above the now-exposed fracture plane to form the upper neck region (this process will be described in detail below). In other words, this area was very quickly eroded down to the solid, ‘rocky’ fracture plane we see and on which the rocky base of the orange anchor is imprinted. The orange line reaches the orange anchor but can’t extend across the solid fracture plane that’s been scrubbed almost clean of dust. It can’t reach the orange dot on the rim because it needed loose neck matrix and anchor debris embedded within that matrix to form in the first place. The line can’t therefore imprint itself on a solid fracture plane. 

Photos 6/7 again show the orange and green lines meeting their body matches but from a very different angle.  

   

Mauve- mauve body match.

The light blue double ridge imprint is partially obscured by a recess (the far end of this recess is shadowed under the orange dot). That’s why the nearer of the two lines stops suddenly. It runs along the base perimeter of the recess, out of view. This recess should be borne in mind for the first orange protrusion under the head rim, described below, when we look at all the lines in more detail. That protrusion slotted in here when the head sat on the body.

Other colours in photos 6/7 are as for photos 4/5.

Thus, two of the four match pairs, green and orange, are directly linked by a visible line running all the way from head match to body match. The other two, mauve and yellow, have lines that extend as far as they can go in the direction of their body matches without traversing Hapi. 

The reason for these lines running between the matches is almost certainly to do with the shedding of delaminated material from between them as the head lobe rose. And why would this delamination process happen only between the particular head-to-body matches that we found in Part 24? It’s because, as stated at the end of that part, they were all very rocky anchor points when the head sat on the body. They didn’t simply match in 2D around the shear line perimeter but extended from within the body, through to the upper surface of the head, in 3D. This is why, when they did eventually shear away, there was plenty of rocky material in these anchor structures to supply the delamination process. 

So, as the head lobe rose and material was drawn out of Hapi to supply the neck, the rising material detached successive layers from the rocky outcrops and carried them up with it. Each delaminated section remained embedded in the neck as it rose, staying in line and in sequence with its other delaminated anchor members. The result was, in effect, an exploded diagram of the rocky anchor that once sat between head and body (or a large chunk of it).

The delamination process would have pulled away the bigger pieces first- those that had been fractured or disturbed right on the shear line fracture plane. None of this is speculation, of course. We already know this happened for the yellow match because the triangular protrusions embedded in the neck below the yellow head rim triangle were matched both to that yellow triangle and to the yellow match point below on the body (Part 24). This means that when the head lobe originally sat on the body, all these protrusions were sandwiched between head and body on the shear line at the yellow match point. They were then strung out, vertically and concertina-style, when the head lobe rose. Since they were the first pieces to be swept up, they are to be found at the top of the Anuket neck as we see it today.

Once these larger pieces had risen away, embedded in the neck matrix under the head lobe rim, the remaining candidates prone to delamination were exposed by the receding surface of Hapi as it supplied more and more material to the neck. Those candidates were still part of the anchor that constituted the body match but they had been buried below the shear line fracture plane up to that point. Therefore, they were less disturbed and flaked off in smaller pieces, being swept away in the matrix of neck material to sit below their bigger counterparts that had gone before them. These smaller pieces are what we see today, forming the four lines in the neck, extending all the way to the bottom. 

We know that scenario applies to the yellow matches even though the line doesn’t extend across Hapi from the neck base to the yellow body match. This is because, as stated above, the shapes in the line of yellow protrusions under the head rim fit against the yellow body match below them (as well as the head rim triangle above them). In other words, we don’t need the line to extend across Hapi to the yellow body match in order to prove that the entire line of protrusions was generated at the yellow anchor point (and probably just in from it as the Hapi surface receded).

This therefore means that in fact three of the four lines are now unequivocally linking their head and body matches: green, orange and yellow. The inferred line to the mauve match will be dealt with in the same manner under the sub-heading below entitled “The Anuket Lines Analysed in Detail”. It was easy to do for the yellow line because all the hard work of shape-matching protrusions was done in Part 24.

THE EVIDENCE THAT HAPI SUPPLIED MATERIAL FOR THE NECK 

This idea of Hapi supplying material for the neck is important and the long, wavy lines in Anuket are the smoking gun that proves it happened. It’s the reason there is a drop-down along the entire length of the shear line to the dusty surface of Hapi. This large volume of ‘missing’ material hasn’t sublimated away, it was drawn up to supply the neck and is sitting in the neck as we see it today. Or rather it actually is the neck because nothing other than Hapi material went into making the neck. 

The reason for this dramatic sweeping-up of material from Hapi is that when the head lobe finally sheared, it was under such tension from spin-up that it had enough upward movement to eject vast slabs from the body at escape velocity (Part 9). Although 67P escape velocity is only 0.8 metres per second, it meant that it was all over possibly after only 2 hours, with the head lobe sitting 1km above the body and somewhere around a billion tonnes of Hapi material swept up and into the neck. 

As more and more material was needed to supply the base of the fast-growing neck, it was drawn away from the shear line that marks the edge of Hapi like a huge, receding wave after it has broken on a beach. After being swept backwards in this manner, the material was swept upwards to form the next section of neck, as it met the base of the neck. Any delaminated rocky pieces that this receding material picked up on the way across Hapi, were swept up with it and remained embedded in the vertical neck matrix. These pieces are now observed as being in sequence with any other delaminated counterparts that happened to have been above or below them on the body. True, they got jiggled about sideways a bit, as in the orange line, but they all remained in vertical sequence.

The process of material being swept back, away from the shear line and across the widening Hapi plain before rising meant that the area just inside the shear line was being eroded away like a coastline in a storm. This is why today it resembles a coastline after a storm, complete with swept back sand and scree, and 100-metre cliffs eroded to their bases in a few hours. This is especially the case at the Babi end of Hapi where the matches in Parts 1-5 were made: eroded cliffs along the shear line including undercut features and a swept-back appearance to the dust. There’s scree lying in line with the direction of sweep. Also, many of the boulders on Hapi were freed from the main undercut cavern just like xenoliths being freed from an eroding cliff- they have trails that lead back to the cavern. 

It could be argued that all this erosion is due to sublimation and the gravity field drawing the scree to the centre of Hapi. However, the neck material had to come from somewhere and this is the only place it could have come from. True, the scree and some boulders have probably fallen out of the cliffs since the major sweeping up of Hapi material into the neck. But it was the major erosion of the shear line resulting from that process which allowed erosion to continue at a much-reduced level. After all, in 11 months since Rosetta arrived at 67P, Hapi has barely changed in appearance despite increasing activity. Rampant erosion isn’t happening and estimates of 20 metres of erosion per orbit won’t happen either- the matches prove that almost no erosion has occurred since the stretch. 

Photo 8- The eroded shear line at Babi.  

 

Key: photo 8 is culled from Part 3 so it shows some matches of the head lobe rim to the shear line that aren’t related to this post or the eroded ‘coastline’. These are the yellow, green and light blue matches. Also a pair of red dots at the end of the yellow line. For our purposes, we can see the mauve match to the right for context. After that, it’s the dark, shadowed curve on the left that’s dotted red. That’s the undercut cove. There are two red dots on the Hapi dust showing the two outside members of a clutch of boulders whose trails can be seen here and traced back to the cove in other pictures. There are four dots showing four steps that have been eroded and the area under the yellow-dotted line is deeply eroded too. 

Turning to the Anuket end of Hapi, where the four coloured matches of Part 24 reside, it’s the same dramatic erosion scenario. It’s slightly less marked here but, in addition, the fracture plane mentioned above was exposed in Hapi below the four matches.

Photo 9- fracture plane below the four matches. 

 

Light blue- fracture plane perimeter. It appears to have a very straight ‘top’ edge as seen from this angle. However, whilst this must be a feature, it could just be a straight line across a fracture plane that extends under the dust of Hapi. So the edge may be the straight line itself or it may be under the dust and closer to the neck base. The dust of Hapi extends above the top blue line and into the shadow at the top of the frame. The base of the Anuket neck runs roughly parallel to the top blue line and it’s in the shadow too. Notice that the left hand fracture plane perimeter line is contiguous with what is usually annotated as the resilient, green ridge that drops down into Hapi below the mauve match. This has often been referred to as a significant dividing line and its usual bright green annotation shows that it’s the extension of the resilient ridge along the slab A extension perimeter.

Mauve-to-green dots- The four body matches, shown for context. Orange and green are almost off-frame on the right. 

The exposed fracture plane is quite deep below the shear line (that’s not very obvious in photo 9) and running exactly from the mauve match to the green match, a trait which will come to be seen as significant in itself in Part 26. The fact that this fracture plane is scrubbed almost clean of dust and debris suggests that it wouldn’t give up its material and so the rising Anuket neck had to steal material from the side directed towards Hathor/Babi from that point onwards. This material supplied the mauve and yellow lines from the left side while the neck area facing the fracture plain monopolised the sparse supply at its base. The latter area included the orange and green lines. 

This partly explains the obvious sideways pinch in the neck on the left side of Anuket. It’s pinched in on the bottom-left side only, and that’s because it would have been largely that area that needed supplying with material once the neck had been mostly formed from material along the shear line i.e. the mass that once sat on top of the now-scrubbed fracture plane. The other reason for the pinch is the 15° rotation of the head lobe (see ‘ticker tape’ analogy below).

The sideways supply of material from the left also explains why the mauve and yellow lines twist round to the left, two thirds of the way down so as to face to the left as they descend that slope of the pinch. They’re facing that way because they’re facing their source of neck matrix material and in doing so, they form a squared-off buttress on the left side of Anuket.

THE SQUARED-OFF BUTTRESS 

 
Photo 10 

The pinching in mentioned above is further evidenced by the fact that this squared-off buttress matches a three-sided-square rock formation peeping out of the dust of Hapi two-hundred metres to its left. Material has been drawn from within this square area, through the open, fourth side. It’s been drawn to the right in the process and retained some vestiges of its squared-off form as it rose. The current shape of the Anuket neck on this side therefore looks as if it’s been extruded through the three-sided square and then shunted two-hundred metres to the right. 

Photo 11 

 

Three-sided square in pink- the formation embedded in Hapi. This is also annotated in photo 10 but is very foreshortened in that shot. 

Curved pink- the base of the Anuket buttress. It’s curved at the base but more squared-off further up.

Red arrow- direction of extrusion of material and of the sideways shunt. 

Yellow and mauve- the bottom extent of the yellow and mauve lines. 

This sideways shunt was most likely a smoother process in reality, just the supply of material from the left, feeding the side of Anuket in the latter stages of neck formation. But it probably was really extruded through the square, even if the sides of the square were being eroded downwards at the same time. If that was the case, the square was like a three-sided box and its rockier sides contained the extrusion process when embedded but were swept up with the neck once they were exposed above the receding surface of Hapi. That would explain the knobbly outer edges running up the squared-off section of neck. A small hump remains on one corner of the box remnant if it was indeed a box (photo 10). Whatever might have happened in detail, the squared-off section of neck must have come from that formation. The fit is perfect as is the direction of flow and orientation of the rising slope.

This supply of Hapi material from the three-sided formation has left the characteristic buttress shape in the base of the neck on this side. There’s a pinching in from left to right, giving rise to a steep slope to the right, up and out of the three-sided formation. There’s a marked set-back or recess behind it (photo 10 again) making it a truly free-standing buttress with a fully three-sided cross section. The sideways indentation that the buttress makes in the neck is probably partly responsible for the lower zigzag (of two) in the mauve line. This is in contrast to the slightly more vertical profiles (and more curved paths within those profiles) of the yellow, orange and green lines due to being in the main body of the Anuket neck. The yellow line falls into step with the mauve line as they descend the slope of the buttress together but it doesn’t twist as suddenly. This is because it arrives at the top of the slope from a little way inside the neck whereas the mauve line twists and zigzags right along the left edge of Anuket.

Photo 12- The zigzags in the mauve line. The top end of the buttress forms the first zigzag indentation as it rises from the three-sided formation that supplied it with material (pink).  

 

The process that causes the pinching in and slope of the buttress is probably similar to that seen in nuclear explosions. The fast-rising fireball sucks dust in towards the base of the mushroom and then up, near to vertical, in a smooth, curved or pinched manner. In fact, the curved stalk of the mushroom is part of the reason it’s called a mushroom cloud and if you swap the rising fireball for the 67P head lobe, you have a very close analogue for the formation of the whole neck, not just the buttress. It’s just a bit more marked there. 

Here’s a video of a nuclear explosion for illustration. It’s the Trinity test which seems to be the best example for our purposes after trawling through many YouTube videos. It captures the essence of the process described above almost perfectly: the head sucking material in from the shear line and then up the stalk of the mushroom. 00:26 to 00:38 is the relevant section.

If you know of a video that illustrates this process even better or for longer, please leave a link in the comments. 

In the case of a nuclear explosion, the explosion itself causes a vacuum which is soon filled by the backdraft, sweeping back towards the centre. This backdraft is laden with dust and smoke. That then gets sucked upwards by the rising fireball. In the case of 67P, no such suction occurred, it was just the adhesive molecular forces in the Hapi neck matrix material at work: that material wanted to remain attached to the lifting head lobe. They probably didn’t have to be very strong forces because everything was undergoing spin-up for the head to detach so spectacularly. This included the neck material and so it too was given a helping hand by ‘centrifugal’ force even if that alone wasn’t enough to draw it up with the head lobe without adhesive forces coming into play. (The centrifugal force was less for the neck material than for the head lobe because it was closer to the rotation axis).

There’s another reason for the buttress being so marked and so and delineated from the nearby neck material in Hathor (the Hathor cliff begins just past the alcove behind the buttress- a sharp, vertical delineation, which will be a large part of a future post). Anuket was where the head lobe tipped up the most (Parts 10 and 20) before rising in a translational sense. This meant that extra Hapi material had to be found from somewhere directly under or near to directly under this portion of the head rim to supply the bottom of the neck in the last stages of the translational stretch. This is because the higher tip had already used up much of the Hapi material beneath it to satisfy the head tip even before the translational stretch had begun. Hathor didn’t need as much neck material towards the end of the head tip and so it wasn’t ‘grasping’ for so much at the end of the translational stretch. In that sense it ‘allowed’ what it might otherwise have taken to be diverted to the right and into the Anuket buttress under the most tipped-up portion of the head lobe rim. 

THE ANUKET LINES ANALYSED IN DETAIL 

 

Photo 13- header reproduced

In Part 17 the yellow set of protrusions was annotated including two in the neck and the main yellow head rim triangle. Several more were mentioned, strung out below the top three but they were left unannotated in case the dotting obscured them. So there are six or seven fairly obvious yellow protrusions that are strung out, one below the other and all of them line up below the yellow head rim match. This photo shows the first two below the yellow head rim triangle. 

Photo 14- Yellow protrusions (including larger yellow dot on the rim and two smaller ones on the neck). 

 

Let’s call this the yellow line (of protrusions). So if we could find long lines stretching down from the head rim below the other three matches, they would be called the mauve line to the left of the yellow line and the orange and dark green lines to the right of it.

Starting with the mauve head match and its putative line, we can start looking below it for protrusions. If those protrusions were parallel in alignment with the yellow line, all the better, as the head lobe’s stretching, tipping and escape behaviour would be expected to engrave the same sort of lines in places that are close together. This is indeed what we see running down below the mauve head rim match. There are several protrusions that are concertinaed out below that match and they are parallel to the yellow line.

Photos 15/16 Mauve protrusions 

   

Very small mauve dots with double-dotted centres- these are the mauve protrusions. The top shape is really part of the base of the mauve head match because it was part of the anchor that’s broken. Notice how the two lower ones are the same shape as this section of the anchor because they peeled away from it just like the yellow protrusions did from their yellow triangle on the head rim. The same shape is reproduced on the body match. Here are three more photos, one of the mauve head match and two from different angles of the mauve body match/anchor to show how they match perfectly at their tops but have this same shape calved off at their base because it’s where the protrusions used to be sandwiched. The shape is marked with a light yellow line. Remember, they represent a mirrored match so the head match is a mirror of the body match. 

Photos 17/18/19- mauve match close up. 

     

Mauve dots- mauve match perimeter.

Red and pink- arbitrary colours used to show mini matches within the mauve match. 

Light yellow (not to be confused with the brighter yellow line between the yellow matches- these three photos were prepared a while back hence the colour choice)- this is the perimeter break line of the missing mauve protrusions. It traces three sides of an apparent quadrilateral. It’s apparent because the fourth sides of the protrusions are embedded in the Anuket matrix, leaving the same three-sided shape visible. The missing pieces, now protruding from the neck below the mauve head match, behave in the same manner as the (brighter) yellow line of protrusions which sit below the yellow head match. They match to both their head and their body marches. Notice how a) there’s a recess below the light yellow dotted line on the body where the shapes would have fitted b) the first vertex of the quadrilateral from the left on the body (and from the right on the head) is directly below the base of the long, thin arrow feature dotted pink c) the obvious flared-out tips at the top of the mauve match on both head and body. 

The two body match shots look different mostly because of foreshortening but also due to completely different lighting angles and perspective (one head-on, the other at a combination of about 70° right profile and 45° superior profile). They are definitely the same feature.

Thus, just as we did for the yellow line, we have matched mauve protrusions at the top of the neck to both their mauve head rim seating and their mauve body shear line seating. This means that we know for sure that the mauve line, as we see it today at the top of the neck, was generated at the mauve anchor on the shear line. By that reasoning, we don’t have to see a line crossing the Hapi dust from the base of the neck to the mauve match. As with the yellow line, we can infer that the mauve body match can be linked to the mauve head match, its protrusions and, by extension, the rest of the mauve line. There just wasn’t enough material to sustain the feed from the mauve anchor while the base of the neck was receding fast across Hapi from the shear line. The mauve anchor itself is therefore concertinaed out at the top of the neck, or perhaps as far as half way down, whilst the bottom of the mauve line in the lower the neck, i.e. the buttress, was fed from the squared-off section once the receding neck base had arrived there. In that sense the mauve line running down the buttress is only nominally mauve: it just happened to be the continuation of material from the square. The square took over, supplying the material rising up the neck under the mauve anchor material. By that time, the mauve anchor material was either exhausted or too far from the neck base to be sucked across and up. 

Let’s now look at the green line. On the header photo reproduced above (photo 13), it appears there are no big protrusions below the dark green head rim match but there is a very obvious line, a string of bumps, that extends straight below it to about a third of the way down the neck and then curves in two graceful arcs to the bottom of the neck. This green line is traceable even across the dust of Hapi, right up to the point of the dark green body match. It’s a line of protrusions of a sort but they are many small bumps, close together in a long, well-defined line rather than half a dozen or so, strung apart. The fact that the dark green line goes through the dust of Hapi to its body match may be due to the actual line affecting the way the dust settles or slightly enhanced sublimation from the line itself, perhaps. It’s anyone’s guess, but the fact that it runs from the more defined dark green line at the base of the neck to the dark green body match would be highly coincidental if it were just by chance. That’s because the green match has already been proven as a robust match in Part 24 without recourse to using its green line to link the two. It would be different if we were trying to argue that the green line was proof alone for a match because it wouldn’t be any coincidence at all if it just ran to that place on the body. It would simply be a piece of circumstantial evidence. The fact it runs between two already robust matching points is highly significant and that means we can be more confident if we see other lines running through the dust of Hapi to join other body match points.

Turning to the orange head and body matches and any possible set of protrusions running between them, we find almost nothing near the head rim. However, there is one obvious one which can be traced back to a point where it nestled to the right of the orange head rim match:

Photo 20- The first orange protrusion. This is probably the finest annotated photo of the whole blog so full zoom is needed. 

 

3 white dots- stalk at the base of the protrusion and its head match (this protrusion looks like a head of broccoli in some photos hence the reference to a stalk). From this feature, you can see that the rock that forms the protrusion needs to be tipped towards us in order to fit- it’s currently foreshortened in comparison to its seating. 

Very small light orange dot in the dark ‘y’ shape to left of the top white dot. These show the centre of the y shape, once again, foreshortened in the protrusion.

Two dark orange dots at either sideways extremity- the width extent of the protrusion. This is not very apparent on the right side of the head rim seating match but the white stalk and a hollow next to it serve as a guide. On the left extremity there’s an upturned curve or squiggle that matches. This left hand orange dot on the head rim denotes the classic orange match point at the base of its recess. This recess is the dark, shadowed area and the reason it’s shadowed is that the top left perimeter of the recess is nearer to us. This corresponds to the the lower side of the step-up to the orange match point on the body after the shear line traces out the yellow triangle. So the left-hand orange dot here is the definitive orange match for the head rim match and it’s further away, corresponding to the higher plateau on which its body match resides. 

When the head sat on the body, this protrusion sat inside the recess mentioned in photos 6/7 above, the one that obscured part of the blue double-ridge imprint next to the orange body match. The recess was flagged up to be borne in mind for this matching protrusion, which was sandwiched inside the recess on the body but under the head rim seating we’re looking at here. 

Light orange dots along the top- this is the top edge of the protrusion and the head rim it presumably fits to. This line doesn’t fit very well but the protrusion is tipped back. It looks better in the next photo. 

Orange line running up the neck between the two matches- the spidery line that links the two white stalks (almost).

Yellow- the yellow line of protrusions including a third one in the neck. 

The matching, dark ‘y’ shape, the squiggle out of its left side and the white stalk prove that we have a match so this protrusion can be said to be the first proper member of the orange line (although the spidery line does extend above it to the seating as well).

There are three pieces of evidence for this match. Firstly, the protrusion matches to its seating on the rim it’s supposed to have come from as stated above. Secondly, it can be traced to this point if a line is drawn from it to the head rim so long as that line is parallel to the much more obvious yellow line of protrusions. One would expect similar behaviour from the orange line so it should be roughly parallel. And the third reason is the actual line linking the protrusion to the orange match anyway- it’s just that it’s not a line of protrusions or bumps, it’s just a spidery line. Photo 21 illustrates this better because the line is thrown into better relief. It shows the line linking the two stalks. 

Photo 21- Orange protrusion with the same annotations as in photo 20 

 

This first member of the orange line has a line emerging from its base that’s more difficult to trace to the base of the neck. But it is a continuous line albeit one that changes guises along its length and sprouts many horizontal offshoots. It appears roughly to match the green line in its meanderings as it descends. The offshoots, being so near to horizontal, are possibly indicative of delamination of a particularly flaky stratum layer that was swept across Hapi from the orange anchor area (under or behind that first protrusion) and on up into the neck.

The orange line across Hapi is much more defined than the green line’s river delta appearance. It joins the matching orange anchor point on the exposed fracture plane. This is a match in its own right since it is a double line that mirrors the double ridge above on the head and even curves at the edge of the fracture plane to run along it (photos 4/5 and 6/7). The double ridge on the head also curves to run along the first fracture plane beyond the head rim (Part 24). 

Once we can see the clear shape of the green line and the fuzzier orange line that mirrors it, we can start to see what we should be looking for in terms of the course of the yellow line and the mauve line as they descend below their initial lines of protrusions. These stop about a third of the way down from the head rim. But if we now look at the lines that run below them, we see that they are wavy and essentially mirror the green and orange lines but in a more exaggerated form. Their waves are nearer to being zigzags, especially so in the case of the mauve line. Then they almost merge towards the bottom of the neck as they both run down the outer edges of the buttress- one on each edge. Clearly, the two lines at this point are no longer mauve and yellow anchor material respectively- that’s all in the upper portion of the neck. But the sweeping up of delaminated material in Hapi only started with the anchors. When they and the surrounding Hapi neck matrix material were exhausted, the sweeping up process moved backwards across Hapi to the squared-off ‘box’ formation and then to the right, forming the buttress. It turned right due to the yellow and mauve head matches being the most tipped-up portion of the rim, demanding the most material to be sucked up into the neck beneath them. 

The exaggerated zigzag in the top of the mauve line may be because it’s on the left edge of the Anuket section of the neck region. The bottom zigzag has already been attributed to the squared-off buttress being drawn to the right (and also head rotation, see the conclusion). As for the second, higher zigzag, there’s a curious area of material that appears to be sagging down under Ma’at. It’s as if it’s head lobe material that has sagged so far down that it’s masquerading as neck material. There’s nothing to hold it in on its left side so this exposed edge may have been more liable to a slight collapse when the neck was stretching due to the stronger gravity field of the large lobe shortly after detachment of the head lobe. 

Photos 22 and 23- The slumped area on Anuket, bounded by blue dots on two sides and the mauve line on the other two sides. 

   

So, despite this slumped area’s self-evident ability to rise overall in the stretch, its movement at the edges would have been held back in the initial stages if the body lobe gravity was an influence. That may have kinked the mauve line. However, as with the lower zigzag, there is a second possible reason for the kink. This time, it’s not the head rotation during the translational lift but an effective rotation in the opposite direction due to head lobe stretch before shearing. This will be dealt with in Part 26. 

This strange area of sagging material is most probably the missing slab A extension material, or more likely, the front half of it while the back half got flung away due to being subject to the greater centrifugal forces nearer the long axis extremity. It’s hard to believe that it could be swept off the slab A extension area like the table cloth trick, clinging to the head lobe but there’s some evidence for this. It’s beyond the scope of this post save to say that the main slippage down on the left of this slumped area is exactly in line with the large circular hole below on the rim of Site A, known informally as ‘the amphitheatre’. It’s not just sitting roughly above it. It’s in line with the section of head rim that kissed the circle when measured back from the mauve match and forward from the rock B match. It looks as if this smooth triangular part of the slumped area was seated on the roughly similarly shaped area the other side of that hole. So if you pulled it out again from its current slump against the neck to see how it used to look, you’d be holding a floppy sheet about 30-50 metres thick with a semicircular indentation in its left side that fits the right hand half of the circular hole below. The other half of the circle match would have been on the edge of missing slab A that escaped while this slab A extension material next door was on the cusp of departing with it but just about held on to the head. This is somewhat more speculative than the rest of this post and indeed most ideas presented in this blog so it should be ring-fenced as a working theory. It has no bearing on the solid evidence in the rest of this post or anywhere else. It was mentioned simply because it’s a section of the Anuket neck that wouldn’t otherwise be explained and we’d be left asking ourselves how it got there and why it had so little to do with neck stretch and the four lines. Even Thomas et al (January 2015) refer to this section with some bemusement as being where Anuket appears to be ‘eroding’ it’s way into Ma’at. That certainly isn’t happening. 

THE BUTTRESS PINCH IN MORE DETAIL

Photo 24- the sweeping back of material in Hapi 

 

Mauve, yellow, orange, dark green- path of sweeping up of Hapi material, starting at the four anchors and receding as material was eroded from the shear line. For the mauve match it turned to the right in the latter stages and ‘sucked’ material from the three-sided formation as it went.

Bright green- Slab A extension

Bright green running past mauve match and into Hapi- the continuation of the very resilient ridge that divides the slab A extension from the undisturbed craters. When it reaches Hapi it is the dividing line between the four obvious matches on one side and much more upheaval on the other side. 

Blue- suggested slab A extension section that went to form the slumped area on the Anuket neck. 

As well as the top zigzag of the mauve and yellow wavy lines (due to the slumped slab A extension material), the buttress can be seen to have been pinched inwards towards the right, contributing to the lower zigzag. This was mentioned above when it was observed that it’s squared off in exactly the same dimensions as the three-sided rock formation peeping out from the dust of Hapi.

This sequence of the sweeping up of Hapi material is why the neck at Anuket is pinched both backwards from the four shear line matches and sideways from the three-sided formation. 

The sideways pinching explains why the mauve line and the yellow line appear to converge somewhat at the base of the neck. They’ve been pressed together from the side. It would also explain why neither of them meet up with their respective body match locations like the green and orange lines do. The two lines have been pinched in so much that, for the mauve line at least, its base has effectively slid 200 metres to the right across Hapi from its respective match alignment, after having slid back across Hapi from the shear line. We know how far it slid to the right because the mauve body match formation or anchor point extends, in effect, across the dust of Hapi in the form of the bright green ridge (Part 24). This ridge is the continuation of the of slab A extension perimeter (Part 22) beyond the mauve match. That bright green ridge abuts the back edge of the three-sided square formation, so the end of the ridge is the point where the mauve line would have been traced back to if it hadn’t been pinched inwards as well, after reaching that point. 

The dark green and orange lines simply slid backwards from the shear line as they supplied material to the neck but they remained in line with their matches due to not being pinched in at their sides. 

CONCLUSION- THE LINES PROVE STRETCH THEORY AND PROVIDE A ‘TICKER TAPE’ RECORD OF HEAD LOBE ROTATION. 

The lines in Anuket don’t simply link the four matches. They serve as elegant proof for the actual process of material being swept out of Hapi and into the neck. In other words, they are another means of proving stretch theory without resorting to head-body matches. 

Although two explanations for the zigzagging of the lines has been put forward, they are only partial explanations and minor ones at that. Most of the waving to and fro was likely due to a) the stretching of the head lobe before shearing (see next part) and b) the 15° anticlockwise rotation of the head lobe as it rose. 

The supply of anchor material for the lines can be seen as being akin to the supply of ink dots on a moving ticker tape. If the tape moves to one side it causes a sloping line of dots across the ticker tape. If the tape moves in the opposite direction, so will the sloping dots. If it moves back and forth, curves or zigzags are drawn. The anchors remained stationary on the body as the head and neck did as they pleased. The anchors supplied the dots in the form of delaminating fragments and the ticker tape is the neck as we see it today. Thus, the lines in the neck, as shown in this post’s header photo, betray the rotational movement of the head lobe as it rose. 

This is notwithstanding the slumped area possibly accentuating the top zigzag of the mauve line and the sideways sweep of material into the buttress accentuating the lower zigzag of the mauve and yellow lines. However, seeing as the green line moves in broadly the same manner as the other lines and yet resides firmly in the body of the neck and a very long way from these two influences, it would seem that head rotation is by far the most important factor in imprinting all four ticker tape lines. Moreover, seeing as the green line is not subject to any other perturbing influences and is the most well-defined of the four it is probably a near-pristine record of head rotation during the translational stretching of the neck. 

So the effect of the slumped area and the buttress on the lines were, after all, minor influences, affecting only the mauve line and the bottom of the yellow line. These effects may have been overemphasised above but they needed to be aired. Any downplaying of their specific influence on the lines doesn’t cast doubt on the mechanisms suggested for their existence (slab A extension material for the slumped area; extrusion from the three-sided square for the buttress). 

Head lobe stretch before shearing would account for the top zigzag as well as (or instead of) the slump of the slab A extension sheet. Head lobe stretch in this area will itself be seen to be a form of rotation. 

The later 15° anticlockwise rotation that happened during the translational stretch probably accounts for much of the slant in the lines at the bottom of the neck and therefore contributes greatly to the slope of the buttress. In other words, the 15° rotation began only after the head lobe had risen to two thirds of its final height and the rotation left that slope in the buttress, i.e. in the bottom third, as evidence. In ticker tape terms, the tape (neck) moved to the right in the anticlockwise head lobe turn, leaving a line of dots sloping from upper right to lower left as it was still rising. The slope of the buttress and the orange and green lines are the real-world equivalent of that ticker tape analogy. The slope is therefore a visual record of the rotation. 

A slight variation on the above paragraph would see the head lobe rotating after, not during, the stretch. It would have drawn its ticker tape line straight upwards due to not rotating in the bottom third. Then, the 15° rotation after stretch would have introduced torsion in those lines and they would have assumed the same slope as if they had been drawn that way on the tape (i.e. the neck). The reason for suggesting this alternative scenario is that the areas between the lines are scalloped just as is observable when box section steel is twisted and the torsion forces scallop the flat faces between the edges. This is particularly clear in the scalloped cross section between the green and orange lines in the bottom third of the neck. And it’s the bottom third which contains the supposed rotation signature. An argument against this alternative is that such torsion after stretch should induce a slope that’s not just in the bottom third but superimposed over all the ticker tape patterns across the whole neck. Of course, it could be that both mechanisms occurred, some rotation during rise and some torsion later.   

TAKE HOME MESSAGE

As mentioned at the outset, the take home message contains the information to be borne in mind for the sub series theme of head lobe stretch before shearing. For this post, there are three points, detailed as follows:

Firstly, the top slope of the mauve, yellow and orange lines between the head rim and the point of the first zigzag. These are parallel to each other and their slope is more marked than the top slope of the green line. 

Secondly, the slumped area, which is thought to be slab A extension material couldn’t have been lifted cleanly upwards being so close to the rotation axis. It seems it was dragged forward in such a way as to become loose and be able to escape along with the head lobe. 

Thirdly, the long, rectangular fracture plane that runs below and in front of all four matches (best view is photo 9, also photo 25, below) is exactly the same length as the large, vertical section of head lobe directly above it. This vertical section, which will be dubbed the ‘vertical wall’ is two strata layers in height and set one stratum level above the rim. There’s evidence of the other strata layers bending around it while it remained upright, unstretched and firmly attached to the fracture plane below. The fracture plane is also exactly the same length as the base of the red triangle of undisturbed craters. By extension, the vertical wall is therefore also the same length as the base of the red triangle. This means that a resilient main anchor (the vertical wall) sprouting four deep-rooted sub-anchors (the four matches) protected the triangle of undisturbed craters behind it while everything else was stretched or ejected around it. That will be the main subject of Part 26 where all the evidence from the first four parts of the sub series will be adduced as evidence for this scenario.

Photo 25- the fracture plane (body) and the vertical wall (head), culled from Part 24. 

 

The perimeter of the fracture plane on the body can be seen as the long, blue line extending into Hapi from the orange body match (although it does actually extend to the green match/anchor). It starts out as a double line because this is the double line of the orange anchor, imprinted on the fracture plane (photos 4/5). It meets with the bright green line that forms its other end boundary. The match for the back of the fracture plane is the back of the first stratum on the head, also dotted blue with double lines for the double ridge that matches its imprinted base below. The vertical wall is the very obvious tall, white face above this line with a green line breaching the bottom of its right hand end. 

PHOTO CREDITS

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

To view a copy of this licence please visit:

http://creativecommons.org/licenses/by-sa/3.0/igo/

All dotted annotations by scute1133. 

 

67P/Churyumov-Gerasimenko. A Single Body That’s Been Stretched- Part 24

THE SERQET-TO-SETH MATCHES (This is the third section of the sub series leading to proof of the head lobe stretching prior to shearing from the body) 

 
Photo 2- unannotated version of header. 

 
Key (since there’s quite lot of detail to these matches, the keys are long and narrative rather than short and descriptive):

Yellow, green and red lines- these denote the head rim and the body shear line where the head rim detached. The red line is for orientation only. It’s where the Part 17 matches take over from this post’s matches at the end of the green line. Other than that it’s irrelevant to this post. The green line dips inwards behind the yellow and red lines on both sides. This denotes a matching structure that is assumed to have run between both lobes when they were seated together. It’s more visible in the unannotated version, below. It’s coloured green to distinguish it as a feature but its front end runs along the head rim and shear line. 

Two larger green dots on head and body- section along the perimeter of the structure mentioned above, which is easy to match (see the close up photos below). These two dots were already shown in Part 23 and when seated together they constituted the ‘three-way junction’ described in that part.

Yellow line- this line denotes the rest of the head rim and shear line for this part. It’s yellow because the prominent triangle and its set of concertinaed protrusions are in the middle and they have always been annotated in yellow. 

Two larger yellow dots on the head and body- these denote the tip of the very obvious triangle on the head rim and its seating position, presented accurately here for the first time. 

Two orange dots- a match within the yellow line. The body dot is set back from the yellow line but the head dot isn’t, even though there’s a distinct v-shape on the head rim too (see below). This is because the head tipped forward, away from us, before stretching upwards. This means that in this photo the head rim is presented much nearer to a side-on position like angling a plate so that its rim is viewed nearer to side-on. Indeed this trait is discernible for the entire run of both lines, head rim and body shear line: the body line is fatter, so to speak, and more curved because we’re looking down more from above to where the head rim ‘plate’ once sat on the body. This trait of complex perspectives creeping naturally into the match lines, as they are gradually plotted out, is a sign of the matches themselves being genuine. It’s a completely unpredictable and unavoidable artefact that becomes apparent only after the plot is complete. If random, pseudo matches were being made all over the comet, it would be impossible to do that while keeping the perspective from messing things up for you on the second or third match. 

Two mauve dots- another match mentioned in Part 23, also in Part 22. The close ups in this post will now show it in more detail. 

Light blue line- on the prominent yellow triangle. This is a crevice matching the edge of the block that the triangle detached from. 

Some readers may detect some drifting up the head lobe to fudge a match near the mauve dot. There’s a reason for this being legitimate and that will become clear in the post after next.

Photo 3 

 
This is a view from the middle distance before we dwell on the close ups. Everything is the same as in the key above. Zooming is needed as the dots are small so as not to obscure detail. This is as close as we can get while showing head rim and shear line matching in the same photo. It’s not the best of vantage points due to the head rim being even more edge-on than in the header. Toggling up and down between the two is recommended although it may be more instructive to see the close ups before really scrutinising this one. The only addition here is the imprint of the double ridge running away from the orange dot on the body. It’s running across the dust of Hapi towards the neck. This imprint matches the double ridge running up the head lobe from its respective orange dot thus proving that this structure ran through both the head lobe and the body lobe before separation. In other words it was a large, single, solid structure like the green formation described above. Indeed, both the head lobe and body lobe counterparts of the green formation and the blue formation above the orange dot, curve round parallel to each other as if loosely related.

BACKGROUND

This is a simple post concerned only with matches. It’s done in the usual style, with the corresponding head lobe and body lobe features demarcated in the same coloured dots. As usual, all scenarios are stated as fact so as to avoid endless qualifying of statements. Of course, the hypothesised scenarios may be wrong. However, this blanket qualification that’s made in each post is looking increasingly perfunctory due to the increasing availability of NAVCAM photos and the mounting evidence for stretch that they show. Apologies for what appears to be superfluous repetition in some places. It’s done to avoid the minefield of potential ambiguities when describing matches. 

The prospect of more matches probably seems rather boring now, after 24 posts, but these ones aren’t boring at all. In the post after next, the fifth section of the sub series, all the evidence from the other four sections will be brought together. These four ordinary looking matches are key, not only to the process of head lobe stretch, but also the massive outgassing at the shear line (Part 7) the Hathor dykes (Part 8) and the removal of slabs A and E (Parts 9 and 23). It will also give a clue to the unique ‘dry mix concrete’ appearance of the neck at Anuket and the sudden demarcation line between that morphology and the completely different appearance of Hathor. So, having a good knowledge of these matches will help greatly in understanding the next two posts. The four matches will be referred to continually in several more posts after that, which address all the above issues as well as implications for Hatmehit and its missing slab.

The four matches were found by using the last available matches on either side along the head rim and measuring along the rim from them to these new specific points; then, the same distance was measured along the body. The last available points are very specific places on the shear line, not general areas. One is the top end of the so-called hollow block wall described in Part 18. It abuts the seating position for rock B in Part 14. The other is the end point of the red line matches in Part 17. Measuring forward from the hollow block wall and backwards from the red line served as a double-check, constraining the four new match points to the exact positions we see in the header photo. This means that these points were absolutely constrained by the previous matches hemming them in from both sides. There was simply no wiggle room to go trekking off across the comet looking for random, pseudo matches in any one of countless thousands of places where some vague similarity might be found. Instead, there was only one possible candidate location for each of the four matches. That means if the head lobe hadn’t detached from the body then the chances of finding small-scale matches when zooming into these completely constrained points would be effectively zero. So if we zoomed in and found no small scale matches to confirm our initial positioning, we couldn’t shift the entire shear line over to a new position where we might have found something that vaguely matched. If there were no small-scale matches, this run of the shear line would remain unmatched, casting some doubt on stretch theory. But of course, the expected small-scale matches were there. 

THE MATCHES

As mentioned above, there are four definitive matches between the slab A extension (Part 22) and the three-way junction (Part 23). The two matches at either end were roughly annotated in the previous two parts but they’ll be firmed up in detail here. The two in the middle are the yellow-dotted head rim triangle, which hasn’t been given a proper body seating position before now, and one other wholly new match. In the higher resolution photos below, you can see that the matches aren’t single points but short lengths along the shear line with several mini matches within each one. The centre points of each short section have a large dot in their respective colour, larger than the ones forming the line they are part of. The main reason for dwelling on these central sections of each match and marking them with a larger dot is that they are all on or very near solid, rocky structures that are sticking out of the body at the shear line. Moreover, their head counterparts extend right through the head rim to its top side. This fact will become more significant in the next few posts. 

The orange match is part of the yellow line because it wasn’t recognised as a strong match and part of a structure until much of the annotating was done. Otherwise it might have been set within its own orange stretch. Similarly, its two ridges are marked blue according to annotation precedent. They should really be orange, like the green structure, to show that the orange match is a structure that ran from head to body. 

The whole section in the middle, between the yellow and orange matches has so many small-scale matches, often dubbed ‘mini matches’, that it is essentially one long match of about 500m. The stretches on either side (mauve to yellow and orange to dark green) are so constrained that the only viable runs they could make are along lines already scored out on the body that are very likely the imprint of the head lobe rim. The head rim has the same shape above these points, after all. There are a few tentative mini matches along these lines too but they aren’t as strong as the rest. Large chunks at either end have mini matches too so these small stretches in between actually constitute a third or less of the whole line in this post. 

So it’s pretty safe to say that the middle half is definitively matched, along with the two end pieces, and that the whole line is or soon will be fully matched for the entire 1km-plus length. This section abuts the Part 17 red matches, making a roughly 2km line from the slab A extension (at the mauve match) to the south pole turn. There are matches along the south pole too but thus far the released photos allow only for large-scale matches. In fact, this post completes the matches all the way round the 67P shear line except for the section across the ‘amphitheatre’, officially known as Landing Site A, which has no solid matches due to missing slab A.

The whole shear line along the body for the four matches is shown below, including the two short sections with scored lines but no definitive mini matches. Much of this line has scree on one side of it and striations or scouring on the other side, which is aligned with scouring on the underside of the head rim rebate, above. That’s a clue in itself.

The following set of close up photos from different angles should make everything clear. They have the same basic key as the header photo and any additional information in their respective narrative keys.

Photo 4- shear line. 

 
Mauve dots- in the distance at the end of the yellow line. These constitute the the mauve body match. The area enclosed by these dots is about the size of the single dot used in the low resolution photo above so this is much more detailed. 

Light blue- same ridge and crevice as before but there is an additional line annotated in very small dots inside the dark green formation, behind the shear line. This will be shown on the head lobe close up photo too. The tiny isolated dot to the left of this ridge marks a rounded dip that is also replicated in the head close up. Zooming is required to see these- when dots are small it’s done so as not to obscure detail. There’s also a stubby pair of light blue lines beyond the shear line by the orange-dotted match. These correspond to a double ridge running up the head lobe from its respective orange dot (see photo 6).

Parts of the large yellow triangle are highly foreshortened due to the viewing angle but also due to the block of material sticking up with its top face running almost along our sight line. It’s worth toggling with other photos to resolve this issue. The 3D nature of this rising block appears to upset the neat 2D match as seen from the header photo. The paradox is explained by the fact that the large triangular protrusion that’s embedded in the neck below the head rim triangle, once sat abutting this block on its left side as we view it, forming a flat platform for the flat underside of the head triangle we see today. More on this in the next post.

In another apparent anomaly, the yellow line staggers to the left as it approaches us (between the larger yellow dot and the orange dot). That’s because it disappears from view for a bit before climbing up and onto the terrace that hosts the stubby pair of ridge ends and the orange match. 

The stubby ridges match a slender, curved, double ridge on the head that will be seen in photo 6. They are dotted both blue and yellow. This is because the small triangle where they join is replicated on the head rim above it so that triangle constitutes part of the shear line and is dotted yellow. Beyond the triangle, the stubby ridges are dotted blue because they are outside the shear line. The ridge pair that matches these two blue lines will be seen on the head as starting ‘too’ high up and tapering together, vertically, to a single point plumb in the bottom of the corresponding v-shape on the head rim. That point is dotted orange in all photos, although the shape of the ‘v’ can change somewhat due to viewing angle. This weird behaviour of the double ridge starting too high up will be resolved in the part after next. It’s to do with the 3D complexity of the shear line at this point. But it’s that very 3D complexity, especially the v-shape, that makes this one of the most compelling matches out of some fifty discovered to date around the shear line. 

Photo 5- shear line from a different angle 

 
Photo 5 doesn’t show the green match. Notice the two dark, solid lines at the orange match. These are where the double ridge on the head was seated. You can even see the actual curved base of the double ridge imprinted on the body but it’s rather whited out here. It’s clearer in photos 2 and 3 and is dotted in the summary photo near the bottom. It’s also clearer in some other close ups and suggests the double ridge feature had depth right the way through from this anchor point embedded in the body to the upper surface of the head lobe, above the rim. 

The bright green dotted line in photo 5 is not the shear line. It’s a ridge running into Hapi and is a continuation of the very straight perimeter of the slab A extension. It will be discussed later in this post. It’s a sharp dividing line between neat matches this side and mayhem with no matches beyond- or at least up to the other side of the amphitheatre (flat crater with rocks A and B in the middle). 

The yellow blob in the middle is a rogue dot. These are sometimes left because re editing can degrade previous annotations.

Photo 6- the head lobe from above. 

 
In photo 6, the mauve match is almost out of sight but will be seen in photo 7 from its underside. 

Notice the very small blue dots showing the ridge and rounded dip within the detailed green match formation as per its twin below on the body. 

The pair of blue ridges above the orange dot can now be seen, starting higher than one would expect and tapering together, vertically, to the orange dot in the bottom of the v.

The isolated yellow dot against the black background of space denotes the first and biggest concertinaed protrusion that sits below its partner triangle on the head rim. This is the protrusion that sat against the block on the body shear line to create a flat platform for the yellow triangle. A few other small pieces were also sandwiched in with it and those are now spread out in a line below it, embedded in the neck matrix. They are out of frame. 

Notice how high up the head rim one of the green lines goes. This is in keeping with the header photo showing the match to the body formation below it. You may notice, on returning to the header photo, that the green dots on the head trace out a shape that’s more square-on to us than on the body. This, despite saying that the head rim was more edge on. It should be the other way round by that reckoning. However, it will eventually be shown that this head lobe match was tugged down violently, more so than any other part of the head rim in this vicinity, hence just this small section being almost square-on in the header.

Photo 7- head rim from below.  

 
In photo 7, the mauve match is much clearer. It can be seen as being slightly fluted upwards at both ends like its body match.

The light blue double ridge can be seen but only from one side. The parallel twin is obscured by the one we see, except for its bottom end-point. That’s marked with a tiny blue dot against the black background, so as not to confuse. Again, the two end-points of the double ridge can be seen to taper to the orange dot in the v-shape on the rim, in a perfect match with its body counterpart. 

Photo 8- focus on the mauve match. 

 
This is a completely different approach for verifying the mauve match. The bright green line on the body is the right hand perimeter of the slab A extension as you look down on the body (slab A extension, Part 22). The bright green line on the head follows a distinctive cliff line along the border of Ma’at. If you sat the head back down on the body, these two lines would join and continue in a straight line, one to the other. The mauve match would be sandwiched at the join of the two lines. Moreover, the bright green line on the body follows a ridge that extends beyond the mauve body match, dropping down into the smooth, dusty Hapi region. It represents a linear outcrop of ‘rock’ continuing along in the same direction. That outcrop is almost exactly the same length and is in the same orientation as the cliff line perimeter on Ma’at, above it. So if you sat the head lobe down, the cliff line would appear to be the same structure emerging from the head lobe. There is more evidence for this, which will be put forward in the next two posts. This continuity from lobe to lobe would be akin to the dark green, three-way junction structure that extends from the body into the head and is visible on its surface well above its rim. The orange match seems to exhibit this trait too, as mentioned above. This means that the cliff-to-linear-outcrop was also likely to have been one robust monolithic lump joining the two lobes when the head was seated. 

Everything to the right of the bright green line on the body is undisturbed i.e. the triangle of untrammelled craters, marked red in the two most recent posts. Everything to the left, i.e. the slab A extension, is disturbed. The cliff line in the head lobe also extends a long way up, just like the three-way junction structure, the two parallel blue ridge lines above the orange match and, to a lesser extent, the yellow triangle. 

Photos 9 and 10- focus on the yellow and orange matches.

Photo 9 is a view of the head rim, which is presented more square-on (i.e. more from above) than it is in photo 10. This is shown simply as preparation for photo 10 because it shows the two obvious curves in the rim between the tip of the yellow triangle and the orange match (curves are dotted yellow). Photo 10 also shows these two curves on the body shear line but the head rim is slightly side-on in that photo so the two curves aren’t obvious at all. Photo 9 allows us to see they are indeed there. Just the two curves, the orange match and the single blue ridge/crevice on the yellow triangle are annotated. 
Photo 9 

 
Photo 10 

 
Photo 10 shows the top side of the head lobe rim and the body lobe in one shot. It’s a pity the whole yellow triangle isn’t shown in the head rim part. However, the perimeter runs just a tad off the top of frame and parallel to it, so it is all there for our purposes. 

This photo captures the yellow and orange matches on both lobes. There are some extra blue ridges too. The fuchsia dots are one-off annotations just for orientation of all the matches here. They’re more faithful because they both adjoin the two parallel mini lines or ridges. 

The curved blue ridge line on the head running from the fuchsia dot to the orange match, corresponds to the very finely dotted line on the body, the one nearest to the two yellow perimeter curves. The body version is very finely dotted because the line is almost indiscernible. But it does get a match to the underside of the rim in photo 12, below, so it’s probably more important than it looks. It also looks too close to the perimeter to match the stated head lobe curve. It could possibly correspond to the slightly less obvious head lobe curve nearer the head rim perimeter. However, the body match is on a moderate slope (see photo 4) so the distance between line and perimeter is foreshortened.

The more obvious curve on the body can’t be the exact match to the one on the head because the triangular protrusion embedded in the neck beneath the head rim triangle used to sit here (its upper, long side may have actually left the very lightly dotted blue line- see photo 12). 

Incidentally, the lightly dotted blue line isn’t visible in photo 4. But it’s telling that in that photo there are lines running down the slope from this point- either slurry dykes or scoring as the head rim and its sandwiched triangle slid forward together. The head rim is thin and frilly beyond this line (similar to elsewhere, Part 5) so it bears the hallmark of gases and slurry escaping from under the rim of the triangular section, when it was seated on the body, only to find themselves trapped under this very last section of floppy head perimeter (when it too was seated on the body). So they pushed up that last section to create the frilly rim. In that case, they are more likely to be dykes like the dozen or so identified elsewhere along the shear line. 

There’s an apparent problem with photo 10. All measurements between matches along the shear line and rim show up a roughly 25% disparity, maybe a tad less. The head rim measurements are therefore 25% longer than those on the body. However, this is mostly due to the head tipping towards us at around 35°. Cosine 35°= 0.819 or 81.9%, meaning about 18% of disparity. This would only apply in full if one surface was face on and the other tipped away at 35°. In reality, they are both tipped away somewhat and the head rim is tipped slightly to the right as well. But it gives an indication that most of the measurement disparity is due to the tip. 5% of the discrepancy is explicable via foreshortening: photo taken at 30km; body matches up to 1.5km further away than the head rim matches. Another 3% would be down to either measurement error or the fact that the perspective doesn’t allow the exact match positions to be located e.g. the bottom of the v-shape that defines the orange match on the head has been marked but it’s probably obscured, a bit lower down. That all adds up to 26%, more than the disparity, probably because the whole cosine proportion doesn’t apply.

And the most important thing of all to bear in mind here is that the header photo shows that the yellow and orange matches are definitely the same distance apart on both lobes anyway. There’s no perspective discrepancy in the header because the two matches run across our line of sight and not along it. 

Photos 11 and 12 show the head rim underside. 11 is just for orientation and 12 is the close up. Remember this is a mirror image whereas up till now we’ve had the luxury of seeing the matches coming through, unmirrored, into the top side of the head lobe. 

Photo 11 

 
Photo 12 

 The only new annotation is slightly darker blue dots that extend from the main light blue ridge line. That’s the ridge or line that leads through the rim to the wide crevice on its top side and which seated itself along the edge of the protruding block at the yellow match point on the body. And that block is the one with the light blue line along its edge and with the pair of mini lines at the end but still a little way from the perimeter. You can see the match here in photo 12 on the rim underside: two mini lines half way up, on the left of the ridge line. 

The reason for the darker blue lines is that, together with the light blue line, they describe a shape that’s similar to one imprinted on the protruding block below (photos 4 and 5). You can even see a small gap between this shape and the two mini lines which is of the same proportions as the one between the shape and the lines on the block below. 

You can also see the double ridges emerging below the orange match. These correspond to the imprint on the body in photo 3, except that the triangular block sticking out below it on the neck also has the two lines so that was seated first. This is the triangular protrusion that sat with its other end against the yellow match block on the body. You can now see its shape defined in the head rim above it. It either nestled in against the blue, dotted lines or in the slightly dark triangular section that’s offset a tad down and to the right. It’s probably the latter as that serves to match up the double ridge lines properly. The blue line running parallel to the rim, the hypotenuse of the triangle, is the proposed match for the very lightly dotted line in photo 10. Either that or it’s the hypotenuse of the dark triangle just below. 

There appear to be even smaller scale matches in all these photos. They haven’t been annotated due to the resolution. For example, there are mini squares along the two yellow curves on the body (photo 10) which seem to mirror those on the head rim (not the biggish ones in photo 10 but possibly much smaller ones on the very edge of the rim). The body ones are clear but the head rim ones never are, either in photo 10 or others. 

CONCLUSION

Perhaps a summary photo will serve as an apt conclusion. It includes everything from the above photos as well as an additional, long ridge in the Hapi region, dotted in light blue. Its match is also dotted blue on the head. It runs from the double ridge next to the orange match dot, turns left and runs parallel to the rim. The head rim version looks as if it’s too close to the rim but the ‘side-on plate’ perspective issue is mostly if not wholly responsible for this. The ‘take home message’ for this post follows the conclusion photo. Despite being last, it’s an important concept for following the next few posts. 

Photo 13 

 

TAKE HOME MESSAGE

All the sub series sections can be viewed as stand-alone posts. But all of them have a take home message, which relates to the information needed to keep in mind for the underlying sub series theme of proving stretch of the head lobe before shearing. The take home message for the necessary points in this post that will be adduced in the next two posts is as follows. 

Although most of the perimeter in this area is now matched, there are said to be four specific, coloured match points. All four are defined by apparently resilient ‘rocky’ outcrops on the body and a head lobe match that isn’t just confined to the rim but penetrates deep into the head lobe structure. Furthermore, the four matches, mauve, yellow, orange and dark green are roughly equidistant from each other and exactly define the base of the long, red triangle of relatively undisturbed craters (Part 23).

So, while the slab A extension was being torn to shreds on one flank of the triangle and the Anubis slab was being hurled into deep space from the opposite flank, and the head lobe was being wrenched from its base, the triangle sat in splendid isolation, untrammelled by the chaos unfolding around it. It seems it was somehow protected by these four unusually solid, rocky matches:

PHOTO 14 

 

PHOTO CREDITS

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
To view a copy of this licence please visit:

http://creativecommons.org/licenses/by-sa/3.0/igo/
All dotted annotations by scute1133.