In order to claim this Earthcache, Read the information below and submit your answers to the questions under the How to Log this Earthcache section. There is no physical container. Observe the best you can. The objective is to learn and have fun.
Welcome to the Avi Kwa Ame National Monument area!
This region of Clark County, Nevada, is called the South County. It encompasses the towns of Searchlight, Cal-Nev-Ari and Palm Gardens, as well as the Avi Kwa Ame Mountain and the valley west of the mountain. Avi Kwa Ame Mountain, also known as Spirit Mountain, is part of the Newberry Mountains. Avi Kwa Ame, a Navajo word meaning alternatively "highest mountain", "mountain" or "rock", and "up above", is a sacred mountain to the First Nation peoples that inhabit the area.
The geology of the area is very diverse. Avi Kwa Ame Mountain itself is itself a batholith composed of S-type granite, granodiorite, shonkinite, syenite, quartz, alkali granite and even rapakivi granite from the Jurassic and Cretaceous Ages. In satellite images you can clearly see alluvial fans formed by erosion of the sediments that once covered the Avi Kwa Ame (Spirit) batholith.
South County granites
Granite in general terms is a coarse-grained intrusive igneous rock, composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It is common in the continental crust of Earth, where it is found in igneous intrusions. It is exposed to the surface via erosion.
Avi Kwa Ame (Spirit) Mountain and the surrounding valley features a variety of granite types, including leucogranite, coarse granite, and quartz monzonite. The Spirit Mountain Batholith exhibits a gradational sequence, with high-silica leucogranite at the roof, or top layer, transitioning downwards into coarse granite and then into foliated quartz monzonite. These types of granite are much younger than those found on the northern part of Avi Kwa Ame, suggesting the area to the north began cooling off earlier while the area where you are standing remained molten for a lot longer.
Leucogranite: This is a high-silica granite, typically lighter in color and fine-grain
Coarse Granite: This is a coarser-grained granite, intermediate in the gradational sequence.
Quartz Monzonite: This is a darker, more mafic rock, lower in silica than the granite types.
How to log this Earthcache:
Send your answers to the following questions before logging your find.
1. Describe the top surface of the boulder on the left. What colors can you see and do you see any intrusions in the rock itself?
2. What type of granite do you think this is? Leucogranite, Coarse Granite or Quartz Monzonite?
3. Grab a piece of paper and write your geo-nickname on it. Take a picture of it near or at the GZ. Post the picture with your log, DO NOT send it to me. Logs without pictures will be deleted.
Sources:
Rocks at the Reception Counter of the Great Basin Science Sample and Record Library., Nevada Bureau of Mines and Geology, University of Nevada Reno.
Various Wikipedia articles.
CO's basic knowledge of Geology.
Many thanks to NVDOT for the information they provided which made this EC possible.
This Earthcache replaces GC77NYD. The name bears no relation to the lesson.