 Driving around parts of Wyoming such as Thermopolis, one can't help but notice all the red rocks and dirt. Much of these red rock outcroppings are part of what's called the Chugwater Formation. This formation is dated to the Triassic period, which occurred 250 to 200 million years ago. The Chugwater Formation consists primarily of red sandstone and is frequently found in Wyoming, Montana, and Colorado. The red color comes from the oxidation of iron minerals in the rock. This formation also shows streaks and spots of bluish gray, which come from reduced iron. Gypsum is frequently found in the formation. The main constituent of the Chugwater is quartz, which is why the rock in the formation is so hard. Because of the lack of fossils found in the Chugwater, it receives little attention from geologists and paleontologists. Legend has it that the name Chugwater comes from the Indian name for a buffalo jump where the buffalo were stampeded off of as a means of harvesting them. The cliff was formed mostly from the red rock of what we now know as the Chugwater Formation. Loosely translated into English, the Indian name for the trap was, water at the place where the buffalo chug. The name for the town of Chugwater, Wyoming, in Platt County is said to come from this formation as well. These red rocks of the Chugwater add color and variety to our Wyoming landscapes. From the University of Wyoming Extension, I'm Barton Stam, Exploring the Nature of Wyoming.