Northern truckee river and surrounding area field assignment
I recently visited the northern part of the Truckee river and the surrounding area that included Amacker Ranch. This is a very beautiful area that demonstrates many geological aspects including varies rocks, plants, trees, and geological structures.
Conglomerate rocks are a clastic sedimentary rock that contains large rounded particles (Geology.com). The space between the pebbles is generally filled with smaller particles and/or a chemical cement that binds the rock together (Geology). This rock looks to have formed from mechanical weathering debris as pebbles and sand combined together to create this rock.
The Jeffrey pine is the dominant conifer in the Lake Tahoe basin (Macrae). “This species and ponderosa pine are the only Tahoe Basin pines that bear needles in bundles of three, and their length (up to 10″) and blue-green color also help to distinguish at a distance these two species from the other Tahoe Basin pines (Macrae).” This particular Jeffrey pine has experienced considerable weathering effects as seen by the almost branchless left side and branch heavy right side.
In this portion of the Truckee River there is clear evidence that massive erosion has occurred. The bank on the left has eroded bank a considerable amount causing multiply trees(far side of bank) to fall into the river. This erosion has most likely occurred because of the force of the river but also due to the often harsh winter conditions.
Granodiorite is a coarse-grained, intrusive igneous rock, similar to granite. It contains quartz and plagioclase feldspar (Geology.com). Granodiorites are extremely common in the Sierra Nevada Mountains along the Nevada-California Border(Geology.com).
This is just a small part of the massive Sierra Nevada Mountains. This mountain ranged formed when the Pacific Ocean Plate was pushed under (subducted) the North American Plate(TIIMS). Glaciers, winter weather, and erosion have since formed the Sierra Nevada Mountains that we see today (TIIMS).
(2005, January). In Geology.com: Rocks. Retrieved July 29, 2012, from http://geology.com/rocks/ Macrae, T. C. (2009, March 28). In Trees of Lake Tahoe-The Pines. Retrieved July 29, 2012, from https://beetlesinthebush.wordpress.com/2009/03/28/ trees-of-lake-tahoe-the-pines/ (2011, January). In TIIMS: Geology. Retrieved July 29, 2012, from http://eh2o.saic.com/tiimsWebsite/Content/BasinTop ics/geology/default.asp