File:The American journal of science (1917) (17967252059).jpg

Title: The American journal of science
Identifier: americanjourna4441917newh (find matches)
Year: 1880 (1880s)
Authors:
Subjects: Science
Publisher: New Haven : J. D. & E. S. Dana
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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Text Appearing Before Image:
296 Shuler—Dinosaur Tracks in the Glen Rose Limestone. A microscopic examination shows that both the indurated layer with the tracks and the shale layer above it contain finely comminuted angular fragments of quartz, which in the shale measure up to 1/10 mm., while in the limestone only up to 1/50 mm. In thin section the limestone layer shows an occasional minute bivalve shell in a ground mass of fine granu- lar calcite with fragments of quartz and clay material. The common association of dinosaur tracks has been with sandstones and shales, rocks which bear visible evidence of Fig. 2.
Text Appearing After Image:
Fig. 2. Near view of Dinosaur track in limestone. littoral conditions. But the dinosaur tracks near Glen Rose, Texas, are found in a hard white limestone, which at the time of the passing of the dinosaur must have been in the form of a stiff, tenacious lime mud forming a surface layer of about three inches into which the foot pressed to depths of two to two and a half inches. Had no dinosaur tracks been found the section would probably have been interpreted as having been laid down in deep marine water and at a distance from shore, since no part of the section shows a calcium carbonate content less than 33 per cent. What then were the conditions under which the tracks were made ? First of all, the dinosaur was walking on a mud surface,

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