Plate IV. Photograph of fossil casts of ice crystals seen on some stony
flags in the upper part of the Eagle Ford at Fossil Knobs, about two
miles northwest of the Chisos Mine in Brewster County, Texas. These may
be characterized as relatively short and scattered. This shows ridges
projecting into the grooves formed by ice crystals on the surface of a
muddy layer originally underlying the layer photographed. Slightly
reduced.
[Illustration: PLATE IV]