Along the Interstate 70 corridor, just before Glenwood canyon, about five miles past the town of Gypsum, there is the small, unassuming town of Dotsero. This little-known town has a very important past geologically, geographically and commercially. In order to understand why this lightly populated town of about 700 people is so very important, we have to go back in time about 4,000 years.
Compared to the Gore Range that was forming around 70 million years ago, 4,000 years is only a short time in geologic terms. If you were standing on the side of the Colorado River just before its confluence with the Eagle River about 4,000 years ago, the ground beneath you would be quivering with sounds like rolling thunder echoing through the air. You look to the north and see a huge cloud of strange white smoke. Foamy cinders spew forth from the volcanic vent, while a thick river of lava, a lahar, forms below. The lahar, moving like a thick milk shake of hot liquid lava, flows from a vent lower on the mountain across the valley floor. The cinders accumulate, forming the classic volcanic crater shape and eventually the eruption fizzles out. However dramatic this sounds, the show was not what you would expect. Called “the Barry Manilow of volcanoes” by local writer Allen Best, the eruption was probably fairly slow and lackluster compared to most volcanic eruptions.
The Dotsero Volcano is deemed a Maar volcano by geologists. Maar volcanos by are created when ground water comes into contact with hot magma under the surface of the earth. These eruptions typically form broad, shallow craters that are comprised of loose gravel like cinders. When this volcano blew up, it buried the trees around it in ash and rock. Scientists used radiocarbon dating to determine the age of the buried trees and in turn, the relative time of eruption.
Now fast forward about 3,800 years to 1865, when Dr. Ferdinand Vandeveer Hayden came gallivanting across the Rockies on direct order from the U.S. government to document and map the newly purchased territories. He spent 12 years collecting data and samples and in 1877, he published his “Geological and Geographical Atlas of Colorado,” one of the most valuable publications of the time. In order to produce such detailed accounts, he needed a place he could use as a benchmark, a “dot-zero.” This is how the town of Dotsero got its name.
Now that the expanding U.S. had a better idea of the Colorado landscape, they were ready to start entrenching infrastructure. A few years later, in 1932, railroads were tracking across the West faster than a barefoot hare on a hot tin roof, and railroads, like rivers, usually take the path of least resistance. So, it was only natural that railroads were built along rivers. There is a major confluence at the town of Dotsero where the gold medal fishing waters of the Eagle River flow into the headwaters of the mighty Colorado River.
This 40-mile section of track connected the Denver and Rio Grande Western Railroad to the Denver and Salt Lake Railway, giving the rapidly growing town of Denver direct access to the West Coast.
The Dotsero volcano is the youngest volcano in Colorado, provides a great view of the intersection of two major Colorado rivers and is the location of a crucial railroad connection. Today, the volcano lies dormant and quiet. The modest town of Dotsero is right off I-70 and if you would like to visit its volcanic landmark, when you get off that exit, turn right twice and wind your way up a dirt road a few miles. You will see firsthand the amazing qualities that make Dotsero a benchmark of Colorado history.
Drew Foulis, a trained Walking Mountains naturalist is a new Colorado native and has fallen in love with the Vail Valley. He spends most of his time outside, usually smelling flowers or breaking rocks.