| Roster |
Date |
Author |
Record |
| Description (summary) |
2003-08-12 |
jl |
This is the "ledge" that surrounds the circle. It equals f326 and f346. We have seen it in past years, but never completely understood it. It is composed of a series of almost- vertical layers (see v249) which reveal rough faces when exposed (see v250). However, instead of sloping into the circle, the layers slope down towards the outside of the circle, giving one the distinct impression while excavating them that one is excavating them from underneath. In other words, it is as if, rather than being a plaster or layer applied to the stone wall in successive layers (as we originally believed), they were applied around and against the accumulation within the circle, along its outside edge. This has led gb to hypothsize that these are the successive layers of rain sedimentation within the fissure around the circle, created either by soil falling into the fissure and then being melted by rainwater or by rainwater itself transporting the mud into the fissure, down the sides of the accumulation. [Input: N812jl.j] |
| Notes on description |
2003-08-19 |
jl |
gb observed today that the face of the mud ledge along the northern wall of k30 looks exactly like the thin, hard layer of mud that clearly coats some of the stones around the circle. This mud face is extremely smooth, but possessing clear vertical striations, as if it were deposited vertically, perhaps by mud pouring down the face of the stones. In some of the examples, drip marks, like those made by wax candles, are visible on the surfaces. If the mud ledge face is the same as those, however, it stands to reason that the mud ledge was created by the same process, that is, layers of mud dripping down the face of the stones, rather than the accumulation, as we have previously argued. It seems to me that such a smooth face could only have developed if there was a space in between the mud layer and the accumulation. gb has suggested that it was perhaps the face of a cut, if they were cutting pits within the accumulation, but then one wonders why it goes around the whole circle, rather than being limited to areas of small pits, and one wonders how it happened in different layers. gb's argument is that two different processes can result in very similar appearances, more specifically that the extremely smooth face of the mud ledge is not visible in all locations around the circle. Therefore, it is possible that the ledge itself built up as we have hypothesized previously, and the mud face along the stones was made as I hypothesized above. Then, they cut the shallow pits, and this cut face developed the same smooth, runny surface because of the moisture from the wall. For this to be correct, however, I think that the extremely smooth surface would have to line up with the small pit, which it doesn't exactly do. On the other hand, the other explanation, that the mud ledge was created by layers of mud running down the stones rather than the accumulation, is equally unsatisfactory, since it cannot explain any of the earlier evidence which led us to our prior conclusion. [Input: N819jl.j] |
| 2003-08-21 |
jl |
The question regarding the smooth, striated face on the northern ledge (see v271a, v271b, v272, v212a, v213) has perhaps been answered. Such a surface could only be created if it was exposed, i.e. it was not pressed against soil. It had to have been created by mud running freely down the face of the stones or the mud layers, on account of its smooth surface and the striations, which are most likely drip trails. The fissure has always had air pockets; perhaps this smooth surface is what formed when mud entered one of the air pockets and could flow freely down the stone face. Conversely, when the fissure was without an air pocket, the process which we have outlined earlier occured, namely, that the new soil stuck in the fissure became muddy and, since it could not flow away, it accreted to the accumulation within the circle and created the rough, upside down faces which we have observed in most of the mud ledge. Since it was created by a different process, we have made the smooth, striated face a new feature, f450. [Input: N825jl.j] |