Travertine Mound

Day 117: The Trail of the Shadows is a quick half-mile loop, mere steps from the Administration Building at Longmire where I work. There are many intriguing features to be seen, among them an easily accessible travertine mound and also Iron Mike, one of the more famous springs in the area.

Quoting from the interpretive sign at the beginning of the short side trail, "The brown mound next to this boardwalk is called a travertine mound. Travertine is composed of soft, white calcium carbonate minerals, primarily calcite and aragonite. Only the warmest springs in this meadow form travertine mounds. As warm spring water reaches the surface, trapped carbon dioxide gas is released into the air, and carbonate minerals are deposited. Small amounts of iron rich minerals stain the travertine to give these mounds their brown color."

While not as colorful as the travertine mounds of Yellowstone National Park, Longmire Meadows' specimens are nevertheless fascinating examples of the same geologic process. The temperature of the hot spring encourages the growth of algae on the mineral-rich mud surrounding the spring's vent, and on cold mornings, it's not uncommon to see these small pools of water steaming as they bubble.