Sunday, November 7, 2010

Aerial Photos Shows Outline of Ancient Lake Florissant

Just west of Pikes Peak and south of the town of Florissant, Colorado (about 40 miles west of Colorado Springs on U.S. Highway 24) lies a scenic mountain valley where a number of petrified redwood stumps dot the landscape. Beneath this beautiful setting are incredible plant and insect fossils buried in the sediments of an ancient lake. These fossils, ranging from large tree stumps to single-celled diatoms, reveal a prehistoric Colorado of long ago. Today the Florissant Fossil Beds National Monument protects these fossil resources.

About 34 million years ago, volcanic eruptions near Guffey (18 miles to the southwest) produced volcanic mudflows (water-saturated mass of ash and rock debris). These mudflows—looking and flowing like concrete—buried a lush valley and petrified the bases of huge redwood trees that grew there. These mudflows also created a dam in the valley, forming a lake about one mile wide and 12 miles long. Volcanic ash from subsequent eruptions formed fine-grained sediments at the bottom of the lake. Plants, insects, and other organisms were entombed in this material. Over millions of years these sediments were compacted into layers of shale. The delicate details of these organisms were preserved as fossils and provide a look at the life and the prehistoric ecosystem of the Florissant valley during the end of the Eocene Epoch.

The approximate area of ancient Lake Florissant is defined in this aerial photo by meadows and treeless sections. The prehistoric lake area (light gray) is seen extending through the center of the photograph and then turns west at the town of Florissant. NAPP black and white vertical aerial photo from 20,000 feet (9/29/1999). Top of the photo is north.


NAPP vertical color infrared (CIR) aerial photo of the Florissant valley from 20,000 feet (9/24/88).  Color infrared film is used to interpret natural resources such as vegetation, soil conditions, water resources, and other features.  Active vegetation appears in various shades of red and pink (intense red colors indicate vigorous and dense growth).  Water that is clean and clear appears black.  Shallow water reflects bottom sediments and appears in various shades of blue. Soil conditions (moisture levels) are revealed by the degree of the gray tone:  dry soils are light gray, moist soils are gray, and wet soils are dark gray.  Top of the photo is north.









  


 








1 comment:

  1. These mudflows also created a dam in the valley, forming a lake about one mile wide and 12 miles long. Volcanic ash from subsequent eruptions formed fine-grained sediments at the bottom of the lake. Plants, insects, and other organisms were entombed in this material. Over millions of years these sediments were compacted into layers of shale.

    http://www.nofilteraerials.com/

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