The upper layer here is the Bonneterre Formation which is 500 million years old. These sedimentary layers overlie the 1.48 billion year old rocks of the Grassy Mountain ignimbrite which is called a nonconformity (a missing part of the geologic record). You can also see a dike within the Grassy Mountain ignimbrite which has been eroded relative to the ignimbrite. The material is brecciated material representing eroded rock from both the dike and ignimbrite. The younger sedimentary layers rest on top of this material.
References
Page 102 - Dicka, A. B., 2012, 101 American Geo-sites you've gotta see: Mountain Press Publishing Co., 250p.
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Van olyan űrlap, vagy nyomtatvány, amiből alkalmazást szeretne készíteni?