Chinati Volcano

In the middle of Brewster County, looming large, square-shouldered and something like an African beast, Elephant Mountain, one of the higher mesas of the region, stands 6200 feet above sea-level. On a clear day it offers vistas of the volcanic past of West Texas; Paisano Plateau, the Chisos, Solitario, the Apache Mountains and in the far distance the remnants of one of the biggest volcanic explosions of all time: Chinati.

Good Morning. I’m Mark Glover with the Trans-Pecos Science Moment, brought to you by Porter’s Thriftway with stores in Alpine and Ft Davis.

When the Chinati Volcano erupted it killed everything within a hundred mile range of its vent. The red hot magma rock that blew into the atmosphere and cooled as ash likely darkened the sky for years, nucleating giant electrical thunderstorms that altered the climate. A span of trees near Candeleria that were walloped with the explosive force fell in a semi-circular pattern indicating the direction of the blast and can still be seen today, petrified. Chinati is ranked as the 20th most powerful volcano in the history of the planet.

Thirty to 35 million years ago, west Texas was a violent place, a cauldron of volcanic activity. And it is this period of time that formed and now defines the geography of West Texas. A very brief geological history of the Trans-Pecos starts 200 million years ago with the deposition of limestone from the shallow Permian Sea that covered the area. A 140 million years later, mountains began to build as plates shifted below the earth’s surface. In the Tertiary Period, volcanism, followed by the Miocene Epoch where tremendous faulting occurred. And then 15 million years of erosion to bring us to the present.

The mountain savannah on top of Elephant Mountain is covered with a dark clay soil, older than most soils of the region, it somewhat protected from the tremendous force of millions of years of erosion, as many of the high plateaus in the region are. Some scientists speculate that when the hot volcanic ash landed, it welded to the already existing rock creating a super hard substance known as ignimbrite and this rock, found at the base of many of our region’s mesas, was more resistant to erosion.

Green Valley, a low expanse of land that can be seen from Elephant Mountain, clearly shows the power of erosion. In some places the desert floor is thousands of feet below the plateaus suggesting tons of earth that has been swept down valleys like Calamity and Terlingua Creeks and eventually into the Rio Grande where, over the years, this earth was pushed downriver into the Gulf of Mexico, spreading Texas across the globe.