Winding into the mountains, U.S. highway 24 closely follows the Ute Pass fault, a major fault that separates the Rampart Range from the Pikes Peak massif and the rest of the Front Range. Starting southeast of Cheyenne Mountain, the Ute Pass fault can be traced for about 60 miles, and heads north along state highway 67 beyond Woodland Park. The fault zone is relatively wide and filled with broken and fractured rocks that create the course of Fountain Creek in Ute Pass.
There are at least three resistant ridges made up of sandstone exposed along Ute Pass and in the Woodland Park area. These can be thought of as “fault slices” of a sandstone rock unit “jammed” in Pikes Peak Granite during past movements of the Ute Pass fault. The sandstone rocks are called “injectites” by a number of geologists to describe this remarkable formation. Generally, the color of the injectites is reddish or maroon, but some of the weathered injectites have a buff discoloration on weathered surfaces that is related to the iron oxide cement present in the sandstone.
Today the injectites remain a source of much scientific debate. This was thought to be a sandstone unit called the Sawatch Sandstone that was deposited during the Paleozoic Era in the Cambrian Period—when there was an explosion of multicellular life. Geologists give names to units of rock that were formed generally in the same way at the same time so they can talk about them and map them. Upon closer examination, it is clear this is probably not Sawatch Sandstone. During a recent field trip attended by seven geologists studying these features in Woodland Park, the scientists began to consider this sandstone was perhaps pre-Cambrian, formed at a time before there was multicellular life on Earth. During the intense and concentrated discussion during this field trip, the scientists considered it a distinct possibility this sandstone was laid down before larger life forms were present; Steve Spence, a geology student at Pikes Peak Community College, climbed a steep slope of this enigmatic sandstone while the geologists were fervently debating. He came back down with an object he had never seen before and brought it to one of the authors (Veatch) and said, “What is this unusual looking thing?”
|Steve Spence, a Pikes Peak Community College Student |
with the trace fossil he found. Photo © by S.W. Veatch
|The tube-like structure or the trace fossil was formed by the creature crawling through this ancient |
sand and can be clearly seen from this side view. Steven Spence specimen. Photo © S. W. Veatch.
Footprint fossils can give us insight not only into the behavior of prehistoric animals, but also into their physical attributes. By looking at footprints we can determine the size, speed, and weight of the animal creating the print. Trace fossils are a valuable source of information on prehistoric animals' behavior and biology.
This is a good example of how science works, and how something can change like the name and age of a sandstone unit. Geologists for decades thought it was the Sawatch Sandstone, and now geologists do not know what the name of the sandstone is or the age of it. Now science has a trace fossil from Woodland Park to add to the understanding of this puzzling sandstone. Scientists will soon probe the mysteries of this ancient sandstone embedded in Pikes Peak Granite and hopefully assign a name and age to it.