These photos were taken on a flight from Grand Junction, CO to Denver, CO. They are a little blurry due to the fact that they were taken with my phone, and I was behind the wing, but I still managed to get some alright shots.
This is the view within a few minutes of leaving Grand Junction.
|The bright white area is an old alien landing strip, or so I've been told.|
Actually, that flat white landform under the wing is the Grand Mesa. It is made up of a series of basaltic lava flows which originated to the east from fissure style eruptions. The flows range in age from 9-11 Ma and overlie thousands of feet Cenozoic to Mesozoic rocks. Basalt slump blocks flank the edges of Grand Mesa creating lakes which are used for recreation. At heights averaging around 10,000ft, it towers above the Grand Valley in which Grand Junction lies at 4,500 ft. Why is everything so grand around here? Well it is home to the confluence of the Grand River (now named the Colorado)and the Gunnison River. Recently (within the last couple years) river gravels have been discovered directly under the lava flows. The origin of these are currently subject to debate as to whether they belong to an ancestral Colorado River, Gunnison River or possibly both! (At the beginning of January I was in Arizona at the Arizona LaserChron Center processing a sample from these gravels. Unfortunately with the new semester starting I have yet to review the data.)
Heading further east, we encounter the West Elk Mountains.
|And a bit less blurry photography as well!|
In the foreground lies Mt. Gunnison with several other peaks in the background. These tell a story of Oligocene volcanic activity in Colorado and are made up of several volcanic tufts and breccias which overlie the same sedimentary rocks as the Grand Mesa. Glacial activity accentuated the peaks into the sharp aretes and horns we see today, although they are much less dramatic than the San Juan Mountains which hold the same history.
Onward to South Park! No, not the TV show, but the actual South Park in Colorado.
|Look at the friendly places everywhere and humble folks without temptation!|
South Park is a synclinal feature and is one of the high basins in Colorado along with North Park, Middle Park and the San Luis Valley. South Park sits between the Front Range to the east and the Sawatch Range to the west which contains several of Colorado's 14ers and boasts the headwaters of the Arkansas River.
While the Arkansas flows south out of the valley, we head north and eastward towards Denver to find the beginnings of a new river, the South Platte.
|Look! Racing Stripes!|
It is here we encounter the boundary between the physiological divisions of the Southern Rocky Mountains and the Great Plains. The displacement in this region along the many faults reaches upwards of 7,000 feet in places. The long ribbons of rock were formed when the Rocky Mountains were uplifted relative to the Great Plains, shoving any rock covering them upwards as well. Chiefly made of the Fountain Formation which is eroded remains of the ancestral Rocky Mountains, these hogbacks run for miles along the Front Range and include sites such as Red Rocks amphitheater in Morrison, Colorado and the Flatirons in Boulder. The break in these ridges about midway in the picture are due to the South Platte River exiting the Rocky Mountains an creating a path out onto the Great Plains.
This brings us to our last photo.
|Hey, how'd it get so flat?|
Here the plain-ness (if that is a word, which I'm sure it isn't) of the Great Plains is seen in full view. The ridge of snow capped peaks in the far background is our rather tiny looking Rocky Mountains. Every time I drive towards the mountains I can't help but wonder what the first pioneers thought as the towering behemoths of the Rockies slowly crept into view. Covered with loess deposits and Cretaceous marine rocks, among others, it is hard to escape the flatness of the Denver Basin area as compared to the Rocky Mountains.
This flight was just one leg of a trip to Philadelphia so next time, we shall continue eastward!