September 20th, Faults and Weathering

Glacier National Park is full of many different types of unique geographical processes.  Although many of these unique processes are not only found in Glacier National Park, the park provides an observable clarity to the processes that helped form this magnificent landscape.  One of the most studied processes inside the park is referred to as the Lewis overthrust fault.  The Lewis Fault is a low-level thrust fault that has taken   a large slab, approximately 160km long and 6km thick, of Precambrian limestone and thrusted it up and over much younger cretaceous shales.  (http://formontana.net/chief.html) 

The Lewis overthrust was created due to an uplift in the western part of the rocky mountains that forced the Lewis Thrust Fault to slightly angle upwards.  This uplift was caused by repercussions from transform fault activity along the North American Plate and the Pacific Plate.  This process creates interesting land formations such as chief mountain.  

Chief Mountain is located near the United States Canadian Border and is very unique because of its arrangement of sedimentary rocks.  It is a mountain composed of manly old limestone and quartz that sits on top of a much younger and weaker layer of shales. 

Another process that has helped form some breathtaking mountains in Glacier National Park is known as pressure release weathering.  Many of the mountains in Glacier National Park were once entirely encompassed by glaciers.  These glaciers would then slowly melt due to forces of increased temperature in this part of the world.  Once the glaciers entirely melted the once frozen mountains begin to rebound.  Rebound is a process in which a mountain “unthaws” and attempts to retake its once natural shape.  However in this process rocks slabs crack, break, and fall away from the mountain. 

 This process leaves very distinct forms of rock faces seen in Glacier National Park.

Sources: 
http://mountainbeltway.wordpress.com/2010/08/23/rocks-of-glacier-national-park/
http://nature.nps.gov/geology/parks/glac/
http://formontana.net/chief.html