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The dorsal surface of the cast clearly reads “CA-19 Onion Mt Aug ’67 Sas. N. Cal”:
These are ridges that appear on the medial side of the heel. They are totally consistent with the “ridge flow pattern” seen in known desiccation ridges, namely flowing around the periphery of the cast, parallel with the plane of the cast:
Here we see the band of desiccation ridges 9cm anterior of the heel bounded by a furrow. Bands of arched ridges bounded by furrows are one of the most commonly seen features in casts exhibiting desiccation ridges. Of all features on the cast, this is probably the most obvious “tell” that the ridges are desiccation ridges:
As an interesting aside, a quick shot of this band of desiccation ridges is seen twice during the Legend Meets Science documentary, once during the segment with Chilcutt, and again during the Skookum cast segment. The editing is such to visually suggest that the CA-19 texture occurs on the Skookum elk cast.
Here is a shot of the lateral side of the cast. The ridges are much larger and broken up than on the medial side. This characteristic alone should be enough of a clue to disqualify them as dermal ridges. Some of the ridges seen here are on the order of 2mm wide:
The toes on the medial side. The “ridge flow pattern” we see here is consistent with the ridge flow pattern of know desiccation ridges, in that they flow as a function of the shape of the track they were made in. The “ball” area of the track forms a subtle dam the side of which the ridges flow along: