Sunday, October 10, 2010

Autumn in Telluride, Colorado

We experienced a fantastic autumn weekend recently in the Rocky Mountains! We stayed in a condominium in the old mining town of Telluride, nestled in a truly spectacular setting in a deep rocky bowl beneath Mt. Sneffels in the San Juan Mountains. The geology here is unbelievable. However, I forgot to bring my camera on the trip but ended up borrowing a friends to take a few shots. Have a look.

View towards the northwest from the St. Sophia Station on the inter-city gondola. Yes, inter-city gondola - Telluride is a very progressive city with a quite adequate tax base that funds the operation of this amenity. It connects the historic district in the valley with the new Mountain Village on the hill. We took the gondola to obtain the view above.

Wayne and Helen on the gondola up to the St. Sophia Station.

Our group posing in the brilliant sunshine of a Rocky Mountain autumn. Don and Anne (left); Bill and Beth (center); and Wayne and Helen (right).

Looking east into the enclosed bowl of the San Miguel River. You might be able to locate the huge Pandora mill building in the lower center of the photo. The majority of the rocks in this view are part of the San Juan volcanics that were erupted violently between about 35 and 30 million years ago. These volcanic deposits are composed mostly of andesite.

Looking north towards Dallas Peak (left, elev. 13,809) and Gilpin Peak (right, elev. 13,619). Both peaks tower above the Mill Creek Basin.

Close-up view of the Telluride historic district in the San Miguel River valley. Note the red and white sedimentary rocks exposed just above the townsite. The red strata belong to the upper part of the Cutler Formation (Pennsylvanian and Permian) and the Dolores Formation (Triassic). The Dolores Formation is equivalent to the Chinle on the Colorado Plateau. The whitish beds above the red beds are the Entrada Sandstone and the Wanakah Formation. Barely visible above these and near the top of the photo are thin beds of the Morrison Formation. To a Plateau geologist such as myself who is used to seeing these units much lower in elevation, it is incredible to see them here in an alpine setting.

View west towards Lone Cone in the far distance. Although having the shape of a large strato-volcano, the peak is actually just an erosional remnant capped by San Juan volcanics.

Another view to the west of Telluride and its mesa-top airport. It was difficult for me to ascertain what unit might be holding up Wilson Mesa on the left but it most likely is one of the Cretaceous sandstones of the Mesa Verde Group.

In places like Telluride, most people's attention is drawn towards the high peaks. This is normally what is deemed as unique and beautiful in such settings. However, what makes the peaks so attractive and eye-catching is actually the result of the extreme erosion which has deepened the valley's. A trip to this part of the world just 3 or 4 million years ago would reveal a landscape just as high as we see today but with much less topography (or vertical relief). The canyons would not be here! Extreme erosion has played just as important a role in developing this landscape as has the uplift and volcanism. I had this same observation while on the trek to the high Himalaya's in 2007. Our eyes are drawn to the peaks in such settings but the real story is in the depth of the valley's, which create the high peaks.

A view up canyon near Telluride. Note how the bedrock strata are tilted up towards the right (east) and become beveled and eroded in the center of the photograph. This beveling is the famous "Telluride erosion surface" which is a quite extensive surface that formed at the end of the Laramide Orogeny. After uplift of the western part of North America between 70 and 40 million years ago, extensive erosion beveled most of the countryside. The "Telluride surface" has been observed as far north as Washington state! You might be able to notice a steep cliff immediately above the two white patches of strata in the right center of the photograph, capped by a dark layer. This cliff, about 150 feet high, is located beneath the pyramid-shaped bluffs carved in the San Juan volcanics. This cliff is composed of the Telluride Conglomerate, deposited as outwash from a former highland on top of the planed Telluride surface.

A remnant of the Telluride Conglomerate pokes above the trees at the St. Sophia station near Telluride Mountain Village.

We walked down one of the ski slopes from St. Sophia Station and got one final look at this unbelievable setting. I hope you have enjoyed this small tour of the upper San Miguel River valley.

3 comments:

Tisha said...

Absolutely beautiful photographs! It makes me miss Colorado worse than I already was. My father used to live in Delores, which isn't far from Telluride. It is great area with very friendly people.

Gaelyn said...

Thanks for the tour and geology. It's nice to put more of the SW into perspective. Such an amazing landscape. How easy we forget about erosion.

Bill said...

I'm here in Telluride trying to make sense of what I'm seeing and very much appreciate your commentary and photos.
Bill Matthews