Pueblo, Co. A flat land. A social life as one dimensional as the landscape. The farthest thing from an ‘international hub.’ Unless, of course, you are a geologist…
The very features that make this location a drab to its inhabitants are what make Pueblo a geological rockstar. Specifically, the Lake Pueblo State Park:
Photograph by John Wark
You may have wondered why the middle of America is so dang flat. Well, this is beacause there used to exist a shallow ocean, right then and there. We know it as the Western Interior Seaway, but it is also called the Cretaceous Seaway because it existed during the Cretaceous Period (145 -66 million years ago), following the Jurassic Period (1).
via Wikipedia
As seen in the image above, Colorado was once engulfed by this ocean. There was a mountain range to the west of the seaway, which constantly dumped sediment into the large body of water. All the sediment deposit eventually turned to shale, sandstone and the like under the pressure of the sea, which preserved a lot of the fossils of the time. Then, the Rocky Mountains began to emerge and lifted the planes, thier dranage shaping the Arkansas River. As the river eroded the land around it, it carved out the cliffs we can see, today, which expose all those sedimentary layers(2). The photo, below, demonstrates those layers:
Jumping off these cliffs is actually a popular recreational activity. However, its popularity is declining as it is illigal and many have been swept under by the currents in the lake. Here is a video of somebody cliff diving and another example of the sedimentary cliffs that can be found all around the reservoir and even further into town:
Because of the layering of these cliffs, they are very useful as a reference to age other geological sites and fossils are no rare occurance as you wander through the park. In fact, Lake Pueblo has been distinguished as a Global Boundary Stratotype Section and Point. It is one of four in North America and one of 43 in the world (3). [Make sure to follow the link in the bibliography to learn more about GBSS!]
Want another brief, yet more detailed, history of the Western Interior Seaway and its relation to Pueblo? Check out this article in USA Today:
http://traveltips.usatoday.com/landforms-pueblo-colorado-58579.html
(1) http://en.wikipedia.org/wiki/Cretaceous
(2) http://www.parks.state.co.us/Parks/LakePueblo/Nature/Pages/Geology.aspx
(3) http://en.wikipedia.org/wiki/GSSP
