The distribution of extinction types in silt-stone from the Red Peak Formation (Early Triassic) of Wyoming and the Spearfish Formation (Permian-Triassic) of South Dakota are summarized in this paper. Results indicate that the amount of nonundulatory extinction, monocrystallinity, and inclusion-free grains in quartz of these rocks is extremely variable. Variability of these characteristics decreases, and the minimum observed values increase, however, with decreasing grain size.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not currently have access to this article.