Shaping Up in Telluride

Telluride is a great location to come and get yourself in shape with hiking, mountain biking or snow sports. There are also options to get yourself out of shape in the many restaurants, cafes and bars. But as you enjoy the surroundings, have you ever wondered how the stunning landscape around you got its shape?

This earth cache will give you some insight into the forming of the amazing valleys and mountains around you. You will need to get yourself to the Station St Sophia. The cache site is a short level distance from there. You can take the free gondola from either Telluride or Mountain Village year round. The gondola may temporarily close due to weather, power outage or other unforeseeable circumstance. Please check with visitor info or the gondola stations for further information.

The cache site is above 10,000ft. Be aware that weather conditions can change rapidly. Bring adequate clothing. Be aware of the health effects of altitude.

Learn something while having fun, and enjoy the incredible views.

Geologic processes can be classified as either endogenic or exogenic. Endogenic processes refer to those forces under the earth's crust and can include geothermal activity, including volcanic activity and mountain building activity. Exogenic processes occur on the Earth's surface and are mostly represented by erosion and weathering. The Earth's surface is being constantly reshaped by the combination of exogenic and endogenic forces. A very simple example of this could be the exogenous force of a very heavy rain shower on a sand dune causing channels in the sand where the water runs. Most landscapes are much more complex with a combination of any number of exogenic and endogenic forces acting simultaneously to produce dramatic and often spectacular landscapes (just as you see around you).

The present day Rocky Mountains formed in the Laramide Orogeny 80 to 55 million years ago. "Orogeny" is a term used to describe the movement of tectonic plates to cause severe structural deformation of the earth's crust. During the time of the Laramide Orogeny, the Farallon Plate was forced completely under the North American Plate. The effect is rather like a hardwood floor moving under a rug creating ridges and buckling in the rug. Geologists believe that the Farallon Plate did this at quite a shallow angle, thus the Southern Rockies are farther inland than the northern counterparts, and created the high wide range that is the Southern Rockies today. It is believed that the San Juan Mountains are some of the youngest in the Rockies due to their distinctive craggy shape. They have less time exposed to erosive forces.

http://upload.wikimedia.org/wikipedia/commons/b/ba/Shallow_subduction_Laramide_orogeny.png

Further shaping occurred with the flow of magma. As the Farallon plate slid under the North American Plate, the friction created magma. This formed a volcanic arc and consisted of dozens of individual volcanoes and vents spreading ash and lava across a wide area. The magma solidified underground. This volcanic rock is brittle and fractures easily with the erosive forces of water and the freeze/thaw cycle.

Perhaps one of the most significant factors in shaping the Telluride Valley you see today was glaciation. It is responsible for the "U" shaped valleys and steep walled mountain peaks. The San Juan mountains may have experienced up to 15 glacial episodes over the last 2 million years, but only 5 or 6 have left glacial deposits. By carbon 14 dating of organic sediments in alpine bogs it is believed that glaciation disappeared from the area 18 000 to 15 000 years ago. Glaciers shape the land by grinding through the land surface much as our earlier example of rain creating an erosive channel in the sand. Glaciers create "U" shaped valleys and push rock and earth debris to the sides creating lateral moraines, or at their end, creating a terminal moraine. Glacial erosion also creates a number of other spectacular mountain features such as cirques, horns, spurs and aretes. When the glaciers retreated and melted they left the valley filled with water which accumulated sediment, creating the flat "floor" that you can see Telluride on today.

Even though the glaciers have gone, exogenic forces continue to shape the landscape around Telluride. These take the form of rockfalls created by the freezing and thawing of small amounts of moisture as it seeps into tiny faults in the rock, eventually causing big fractures. Mudslides occur as areas of earth collapse under the weight of water. Avalanches occur during the snow season. Evidence of all these forces can be easily observed from the roads from Durango to Ouray to Telluride to Cortez.

Sources:
"Origin of the Landscape of the San Juan Mountains" by Rob Blair, Mountain Studies Institute
Wikipedia: Laramide Orogeny, Rocky Mountains, Geology of the Rocky Mountains, Farallon Plate.

Logging Requirements:

Please email your answers prior to logging your find. All emails will be answered as soon as possible, usually within a couple of days. Logs without emails will be deleted.

According to the information above and that available at the listed co-ordinates please answer the following questions:
1. What are the 4 minerals listed and what created them? Do you think this in endogenous or exogenous?
2. What process had the biggest effect on the landscape surrounding Telluride? The view of Telluride should give you a classic example of this. Exogenous or Endogenous?
3. What are the names of the trails beginning very close to the cache site?

4. *optional* Tell us how you got into or out of shape while visiting Telluride
5. *optional* Upload a photo with your log of you or your group with your GPS getting into or out of shape at Telluride.

Additional Waypoints
MV35X9C - Mountain Village Free Gondolar Station
N 37° 56.202 W 107° 50.707

TS35X9C - Telluride Free Gondola Station
N 37° 56.163 W 107° 48.824