The formation of rocks at Rattlesnake Ridge
Volcanic activity has been the main contributor to the formation of much of the rocks and sediments seen at Rattlesnake Ridge. Over millions of years, primarily in the beginning, lava flowed from ancient eruptions and solidified into basalt, forming the regions predominant rock type. Sedimentary rocks, such as tuffs and breccias, developed from volcanic ash and debris deposited during eruptions.
Sequence of Events
The region in which Rattlesnake Ridge is in experienced significant volcanic activity millions of years ago. During eruptions, volcanic ash and debris were expelled (4-3 million years ago), which accumulated in the surrounding area. The materials would eventually become compacted and cemented to form tuffs and breccias (3-2 million years ago). Erosion and weathering would eventually break down the surface and reshape the landscape (ongoing since around 2 million years ago). The tectonic forces would contribute to the uplift of the region, raising Rattlesnake Ridge higher above the surrounding areas. The combination of all these factors helped create distinctive geomorphic features like steep cliffs, ravines, and rock formations through out the region and around the lake.
Plate Tectonic Setting and Fossils
The region, and state of Washington entirely, is located on the Juan de Luca Plate, and on a broader scale, on the North American Plate. Much of the fossils found here are plant, invertebrate, and Pleistocene mammal fossils. The fossils include mollusks and echinoderms, and even more interesting, mammoth, and saber-tooth cat fossils!
Comprehensive Fossil Map
Photo Credits/Citations
All (real) photos, including backgrounds were taken by I (Coug student). Maps were acquired at:
https://www.burkemuseum.org/static/cruisin/wa_fossils.html
https://www.nps.gov/subjects/geology/plate-tectonics-subduction-zones.htm
Create Your Own Website With Webador