14 research outputs found

    Experimental determination of the direction of finger flutings.

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    A. Experiment: some crushed is prepared tuff, then placed in a small flat container, moistened a bit, beat and grooved with a finger on its surface. Result: on the bottom of the trace, some reliefs like scales lifted up in the opposite direction of the finger passage are observable. The black arrow indicates the direction of the trace; white arrows the scales. B. Circular Panel, trace C1a. The scales are visible on the bottom of trace (white arrows) and show the direction of the finger fluting. (TIF)</p

    Analysis of the Triangular Panel and especially of its left part.

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    a). Survey of the finger flutings of the totality of the panel. It permit to situate the left part of the panel which has been studied particularly and specially the three preserved triangles A, B and C. b). Orthophoto from the photogrammetry of the left part of the panel. The two triangles A and B are clearly visible, the triangle C with some difficulty due to its alteration. c). The same surface with its contour lines which give the surface relief. The lines are equidistant sections (1mm) parallel to the average plane of the panel, not horizontal. d). A coloured model representing the microrelief of the panel. Red indicates concave surface (relative to the observer’s axis of vision), blue indicates convex surface. Thick line at 0 of the scale indicates flatness of the surface. The units of bending intensity are given in colour range from -0.18 (convex) to +0.08 (concave) for curvature, i.e., from 8 mm to 10 mm for radii of curve. The colour range on the right shows the range and gradation of the panel’s colouration: red and yellow are the concave surfaces (for the observer), green and blue the convex surfaces and, at the limit of yellow and green, the areas without curvature. e). Detail of the groove along the left side of the triangle A. Arrow 1 shows the beginning of the strong slope, Arrow 2 shows a narrow band corresponding to the part of the groove on the side of the triangle. Arrow 3 shows a red band corresponding to the deep part of the groove, Arrow 4 shows a wide yellow stripe corresponding to the other side of the groove with a very gentle slope. (Y. Egels, see S4 Text). (TIF)</p

    Location of undisturbed deposits near the LRC I cave entrance.

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    The map locates the two orthophotos in the centre of the figure. The entrance of the cave, on the left orthophoto, is underlined in black. The dashed horizontal line corresponds to the altitude of the overhang to the pillar room as well as to the lower limit of the ceiling of the cave entrance. Below, the LRC II photograph shows only the upper part of the stratigraphy of this locus (Fig 5B), marking the period when sediments began to deposit on the slope. On the left, LRCI-a (Fig 5A) shows the middle and upper layers inside and outside the cave. Bottom right, LRCI-b (Fig 5A) also illustrates the same middle layer as found in LRCI-niches 1 and 2, but inside the cave entrance. LRCI-c (Fig 5A) shows the location of sediment remnants trapped in ancient and small galleries created by erosion in the hard cretaceous stone, belonging to the deposit which completed the sealing of the entrance. LRCI-d shows sediments very similar to those of LRCI-c (Fig 5A) which continued to accumulate for some time after the cave was closed. Altitudes are given to clarify the location of these different sections. The lower view of LRC I-niche 2 is from 1975 (Photogrammetry Iconem).</p

    Description of La Roche-Cotard Cave (locus LRC I).

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    A. Lithological map of the cave floor. B. XY section in the Pillar and Lemmings Chambers (location in A). The elevation of the ground surface increases steeply from the entrance to the Lemmings Chamber, and then only very slightly from SE to NW till the Hyena Chamber (1.5 m). 95% of the sediments that occupied a large part of the cave were removed during the 1912 excavation. Layers to the SE: Middle layer (b), Upper layer (a), Disturbed layer (r). Layers to the NW: Compact clayey layer with tuff gravel with bone fragments and coprolites (3). Sandy layer with soft reddish clay pebbles (4). Disturbed layers: (1), (2) and (r). The three arrows show the place of the overhang (50.75 m NGF, Nivellement Général de la France: general levelling of France) extending from the entrance of the cave to the Pillar Chamber.</p
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