As you stand in Telluride's box canyon and look up at the towering mountains where miners toiled for gold and other minerals, you might first want to know about all that gold ? and whether or not any of it is still up there. But if you stare up at those mountains long enough, you might begin to ask some different questions about them thaw hills. You may wonder, for instance, why are the peaks so jagged and why do they shoot up 4,500 feet from the valley floor like that? What's up with all that red rock, and how the heck did gold get up there, anyway?



The Telluride Colorado region, located in the San Juan Mountain range, has been shaped over millions of years by both changes in the climate and the formation of various rock layers. Originally this region was flooded by a vast inland sea until a mountain building episode called the Laramie Progeny began pushing up the land 70 million years ago. A period of volcanic activity followed about 5 million years later, which substantially added to the mass of these mountains." There were eruptions of volcanic activity in the area which shaped the Colorado mountain vacations near us," explains local geologist Marcie Ryan.

The Telluride Colorado valley shows distinct evidence of the effects of glaciations. The valley itself is a classic U-shape, indicating a glacier carved out its walls. Above the valley, Bridal Veil and Ingram basins are textbook examples of "hanging valleys" or valleys carved out by smaller glaciers that couldn't keep up with the main one. Other visible clues to glaciations are called "moraines." Society Turn is the site of a large terminal moraine." A terminal moraine is where the front of the glacier pushes debris in front of it," explains Ryan. "When the ice stops moving and starts melting, it leaves a ridge that extends across the valley. After the glacier started melting, the valley filled up with water. The valley floor is filled with 500 feet of lake sediment."

Down valley from Society Turn, the profile changes from a U- to a V-shape, and according to Ryan, the land here was carved into a narrow valley by water rather than ice. On highway 145 between Placerville and Telluride Colorado, several layers of rock are visible on the hillside above. According to a chart provided by Ryan, there are 19 distinct rock layers or formations around Telluride Colorado, varying in thickness from 80 to 2,000 feet. Between mile markers 77 and 75, excellent examples of this stratification can be seen. The most visible layer in the lower canyon is the 1,150-foot thick Cutler formation, which was formed around 220 million years ago. Consisting of sandstone and shale deposited by streams, its rust-red color comes from the iron-oxide rich cement that binds the grains of sand together. Above this layer is a very distinctive and unusual black layer made of petroliferous limestone called "Pony Express." This layer is 155 million years old.

Additional rock formations are visible around Telluride. By Society Turn, people often practice climbing on an outcropping of rock that is part of the Dakota formation. Formed around 100 million years ago from sands deposited by streams, this 150-foot thick hard and tan-looking sandstone layer is the top rock surface holding up the nearby mesas.