D1 Synorogenic Strata:
This layer is composed of approximately 1,500 feet of alternating layers of sandstone from ancient river channels and mudstone from ancient flood plains. These layers were deposited during the early part of the uplift of the Front Range by rivers similar to the modern Platte River in northeastern Colorado. D1 Synorogenic Strata are coarse-grained along the Front Range and become fine-grained and coal-like to the east. These sediments were deposited in the Cretaceous Period and Paleocene Epoch (68-56 m.y.a). Typical fossils include petrified wood, leaves, dinosaur bones, and mammal teeth.

A brilliant red clay layer up to 60 feet thick lies on top of the D1 Synorogenic Strata. This red clay formed as ancient soil, similar to modern red soils that have formed in the moist climates of the southeastern United States and the Amazon Basin of Brazil. The presence of the layer suggests that it was exposed and weathered for a very long period of time, perhaps as long as 9 million years. The clay is mined to make bricks.

Click On Layers
A) The bank of the Amazon River near Fonte Bea in Brazil shows the rusty red color of tropical rainforest soil.
B) Overview of Paleosol at Calhan.
C) Close-up of Paleosol at Calhan.


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