V- vertical wall.
Light green- unzipped layers
Bright green- delaminations of a massif that used to be just the central one attached to the top layer of the wall.
Dark green- the green anchor match. The base of the wall nested between these two matching layers when head was attached to body.
The preponderance of green is due to an ever growing array of features with specific allocated colours
Photo 3- relationship to the Anubis slide and “landslide” massif.
Fuchsia (four lines):
Bottom left: the February 2016 “landslide” massif that had an outburst as a result.
Bottom right: the former seating for the massif and for the head rim that curved round the massif.
Second from top: this sharp turn in the head rim curved round the massif on the body at their common shear line seating. It also hosted the top end of the vertical wall i.e. its other end from the dark green anchor when flat on the body. The wall was flat and buried behind the curve, and under the head rim.
Top: the part of the vertical wall that nested into the curved head rim when clamped to the body. (It includes Nut, which is not an eroded depression).
This post is mostly cut and pasted from the bottom of Part 29, published in December 2015. The vertical wall pushing through is related to a whole host of crust slides and delaminations on Anubis, 1000 metres below on the body. Indeed, its shearing and premature herniation when the head lobe was still on the body, is the indirect cause of nearly all the Anubis slides. So it’s an important aspect of stretch theory and should always have had its own post.
The cut and paste refers to other text in Part 29 but it can be read as a stand-alone phenomenon. However, going to Part 29 to get some more background wouldn’t do any harm:
The vertical wall layer was buried one layer down beneath a single upper layer [see Part 29 for more photos but you can see it in the photos below]. There is also evidence for this on the body, 1000 metres below. It means that the wall tore its way through that layer and tipped upwards under the tension of stretch [herniating from the body through the proto head layers] so as to become more vertical, when viewed in upright duck mode. It had a greater tendency to do this than any other ridden-up stratum because it had its two ends ripped away at Anubis and Ma’at when the wall and Ma’at were on the body.
The mechanism for this surgical excision of the wall from its respective layer is quite simple and based on the clear stretch signatures presented in Parts 22-28. It will be explained in an upcoming post.
The tipping-up of the wall also explains its wide, smooth expanse. Possibly even riven-looking. It’s because it was formerly the upper facet of an onion layer stratum that was buried in what was formerly the single-body comet.
We can now go back and see how the vertical wall pushed right through the onion layer above it.
Photo 4 is the photo 1 header with different annotations and shows the vertical wall side-on.
Photo 4- the vertical wall pushing through the onion layer above it. This happened when still attached to the body while the head lobe was herniating under the tensile stress of stretch. So we are seeing the result, set in the head lobe after shear and will now reverse the process in our minds’ eye.
Bright green- the same matches as above. Notice how neatly symmetrical they are in their separation when seen here in profile on the horizon. They’re spread along a line almost parallel to the paleo rotation plane (photo 8 Part 29) as one would expect if they separated from one central lump under the tensile force of spin-up.
Light green- one of these lines runs along the bottom of the vertical wall which is the same as saying it runs along the top of the rim stratum. The other one runs along the back of Nut, which is defined by the onion layer that moved aside to make way for the wall pushing through. When that layer meets the rim layer back at the top of the wall, those two layers become one single layer.
The two light green lines form a very symmetrical shape with the top rim of the wall running right down the centre. The top rim of the wall is of course the join line where the two sections of the single onion layer will zip back together. The three bright green matches are perfectly silhouetted here, which helps to visualise the process.
If you played the movie in reverse and pressed the vertical wall back to where it used to be, under the surface, you would see the two outer, bright green dots move towards each other and merge with the central dot. That means the Nut layer and the rim layer would close together over the wall, meeting at its top rim, with all three bright green matches nesting together in the middle.
The two outer, sliding layers would become the one onion layer they always were when on the body. That single layer used to sit above and parallel to the wall when the wall wasn’t tipped up ‘vertically’. “Sit above” in this case means in the conventional strata sense i.e. with the wall stratum merged back with its respective onion layer, sitting deeper into the comet and the zipped-up layer sitting flat on top of it. It doesn’t mean ‘above’ as in ‘higher up the head lobe’ as we’ve been using the terminology for the head lobe’s ridden-up onion layers. Both layers, the wall and the zipped layer above it, sat flat on the body before shear (although there may well have been a proto-lump).
Today’s impressive-looking wall was therefore once just a buried section of an ordinary onion layer.
During the ‘reverse replay’ the two outer layers would perform their meeting back up in a perfectly symmetrical, equidistant slide.
The two outer, bright green matches close either side of the central match as we view it here, one clamping in front, towards us (the Nut component) and one behind, away from us (the rim/ridge component). This, along with the fact that the long Nut match is sitting wholly within its respective layer section means that the two sections of the layer zip very tightly back together in the middle, along the top rim of the wall.
Red- these three layers are (a) the two ridden-up layers from photo 4 Part 29 that were carefully outlined along with the red finger and three blue scallops and (b) the smudged third layer that wasn’t outlined in that photo but had its matching three scallops annotated. Now that we can step back and see the vertical wall pushing through, we can see that these three layers were delaminating around the edge of the split so as to accommodate the wall coming through.
Regarding the main section of wall pushing through, there are just two sections of one single layer which unzipped above it and slid back spectacularly to where we see them today. But these three red-dotted layers at the side can now be seen to be extra delaminations concertinaing out across the smaller gap at the end of the split: one is from above the rim stratum section, i.e. from above the dark green head rim match; one is from below the Nut section; and one (the middle one) was sandwiched between the two. All three were nested at the rim over the green rim match and the full nest of four layers originally sat in the dark green anchor tray on the body.
UPDATE ON 29th AUGUST 2016
Here’s the same photo with the ‘unzipped’ lines extended to where they kiss the head rim.
It’s no surprise that they kiss the fuchsia dots because before the vertical wall herniated through the layer above its current top (Nut) was nestled into this vey curve. This is the curve that matches to the curve on the body and this is why the “February 2016 landslide massif” on Anubis was left free to slide back across Anubis after the wall tore away and herniated upwards.
The reason the fuchsia match on the head is tilted up more than the match on the body is because of the herniation process itself. That caused a bell rim all round the back of the head lobe rim. The premature vertical wall herniation was key to exacerbating this process in the vicinity of the fuchsia dots and the section of head rim down to the green anchor match. This is a clear dog-leg in the head rim which matches to the body (Part 17). It hosted the vertical wall when the wall was originally a flat onion layer like all those around it. That was when the vertical wall was on the body, out of sight one layer down and sandwiched under the still-attached head lobe layers.
This is an illusion. It’s a real brick wall but there’s more to it than just a brick wall. Some people never see what it is. It’s been the subject of reams of frustrated discussion on Facebook and Twitter. When you do eventually see it, you’ll kick yourself and wonder how you ever could have missed it.
Then you’ll be saying, like many for whom the penny dropped, “I just can’t ‘unsee’ it, now that I’ve seen it”…
…And then, you’ll know what it’s like for me and Marco Parigi trying to explain what we’ve seen on 67P and can’t unsee.
NOTE: No Spoilers giving the answer in the comments please!
MARCO PARIGI’S BLOG NOW WITH MANY STRETCH AND PERIHELION CHANGE FINDINGS:
Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
To view a copy of this licence please visit:
All dotted annotations by A. Cooper