Ancient wyoming Once straddled the Equator, Geological Evidence Reveals
JACKSON HOLE, WYOMING – A groundbreaking analysis of ancient volcanic deposits in wyoming is rewriting the state’s geological history, confirming it once lay near the equator millions of years ago. New research focusing on the Kilgore Tuff and Huckleberry Ridge Tuff – remnants of massive Yellowstone super-eruptions – provides compelling evidence of a dramatically different past for the region, and illuminates the forces that shaped the iconic landscape of Jackson Hole.
The story of Wyoming‘s equatorial past is etched in the angles of these ancient volcanic flows. Geologist John Hebberger Jr. has observed that the Kilgore Tuff, formed 4.5 million years ago by a Yellowstone volcano located west of present-day Wyoming, dips at 22 degrees.The younger Huckleberry Ridge Tuff, created two million years ago in the current Yellowstone location, exhibits a shallower dip of 11 degrees. These angles aren’t random; they indicate the initial movement along the Teton Fault, the geological feature responsible for the down-dropping of the land that would eventually become Jackson Hole. Understanding this ancient positioning and subsequent tectonic activity is crucial for assessing long-term seismic risk and predicting future geological events in the Intermountain West.
Millions of years ago, the landmass encompassing modern-day Wyoming wasn’t where it is today. Continental drift placed it much closer to the equator. The Kilgore Tuff’s formation, predating the current Yellowstone hotspot’s location, occurred when the ancestral volcano was situated in a region resembling present-day Oregon. Over eons, the North American plate shifted, carrying Wyoming northward to it’s current latitude.
This movement wasn’t without outcome. The faulting that created Jackson Hole also resulted in the loss of the western portion of the Gros Ventre Mountains, which were effectively truncated, once extending further into eastern Idaho. The study of these ancient tuffs provides a window into the immense geological forces that have sculpted the American West,demonstrating a dynamic Earth constantly reshaping its surface.
