ARCHESA Walk

Through the DesertMoab, Utah

Heather McNennyGeology 103, LTCC

Professor Mark LawlorJune 20, 2013

CONTENT• LOCATION, GEOGRAPHY, AND

MAP

• BACKGROUND of INFO 

• GEOLOGICAL HISTORY

• COLORADO RIVER

• FLORA

• FAUNA

• BIOLOGICAL SOIL CRUST

• ROCK SAMPLES

• REFERENCES

LOCATIONSoutheast Utah

mapofutah.net

Background of InfoMost of the information gathered was during a trip I took this June. The information came from Arches National Park and Park Rangers. Any other sources used will be listed in the references page.

All of the photos were taken on this trip, unless otherwise stated.

Geological History

• 300 MA, a sea flowed into the region and eventually evaporated, leaving behind an evaporate bed of salt. This salt bed is what lays underneath this area, causing the arches, monoliths and spires.

• Desert conditions during the Early Jurassic brought thick deposits of Navajo Sandstone ,followed by deposits of Entrada Sandstone placed by streams and wind.

• Due to the weight of the sandstone cover, the salt bed underneath liquefied, thrusting rock up creating salt domes.

• Faulting occurred between the salt domes causing the imposing "Moab Fault."

• Erosion further created the landscape of the arches, leaving the Navajo and Entrada Sandstone cover.

• Water forming to ice in cracks of the sandstone has caused further erosion from the expansion and contraction of the water. Wind helped to clear out debris, and cause further erosion. The layers of fins in the rock strong enough to overcome the erosion are what provide the arches today.

The Colorado River

Cutting through the desert is theColorado River.

• The Colorado was formed as a result of the Laramide orogeny that pushed up the Rocky Mountains.

• This orogeny caused a stream running westward, draining the water left behind from the inland ocean of the Cretaceous period.

• The Colorado is responsible for cutting dramatic geologic areas such as the Grand Canyon, and the Colorado Plateau.

• Volcanic basalt flows dammed the Colorado River into the Grand Canyon 1.8-10,000 years ago, backing the river up 500 miles, all of the way to Moab. As the dams eroded, it caused major flooding, and waters up to 700ft barreling through the Grand Canyon area.

FLORAPinyon Pine- Known for producing pine nuts. From the Pinus species, with two major sub species: Pinus Edulis and Pinus Monophylla. Located all over this area. The root system is very strong, and can break rock in search for nutrients. Conifers such as the Pinyon Pine evolved from gymnosperms of the Devonian Period of the Paleozoic Era, reaching their peak diversity in the Mesozoic Era.

Prickly Pear Cactus- Known as an edible cactus for both

humans and animals. Found all over this area.

Common in arid conditions in the Western

Hemisphere. Due to the cooling in the Cenozoic era, it created arid conditions.

This led to the evolution of xerophytes. A particular xerophyte which was a jungle thorn bush is the

relative of all cacti.

FAUNA

Long Nosed Leopard Lizzard-"Gambelia

Wisleizenii" Included in genus "Crotaphytus"-

Found crossing my feet. Common in Colorado

Plateau Deserts. Ancestry prevalent in the Pilocene-

and early Pleistoscene.

Mule Deer-"Sensu Stricto"- Evolved from Black Tail

Deer. Originally dating back to the late Neogene with

the introduction of hooved mammals.

Found grazing near Pinyon Trees. They are known to

feed on conifers and other desert plants such as sage

and other shrubs.

BIOLOGICAL SOIL CRUST

Critical part of desert ecosystems that

encourages life diversity and nutrient cycling.

The crust is formed by cyanobacteria, fungi,

lichens, and other bacterias, holding together the crust. This protects it

from erosion. The bacteria adds nutrients to the soil supporting vascular plant

life.

ROCK SAMPLES

Quartzite-A metamorphic rock

originating from quartz sandstone. Due to tectonic

forces, pressure and heat metamorphose quartz

sandstone into quartzite. When it cools, the quartz crystalizes, and fuses the other materials together. This rock is hard, and has an outer layer of quartz

sandstone.

Quartz Sandstone-A sedimentary rock

containing 95% quartz. Formed by cementation of

sand grains. It generally contains calcium

carbonate, silica, or iron oxides. Its hardness is

determined by it's cementing material.

REFERNCESMAPS- mapofutah.net. Web. June 20,2013.

National Parks Service, Arches National Park. Web. June 20, 2013.Evolution and Phylogeny of Cacti. Dalhousie Collection of Cacti and Other Succulents. Web. June 20, 2013.

Gambelia Wislizenii. The IUCN Red List for Threatened Species. February, 2012. Web. June 20, 2013.Rolf O. Peterson. Deer of the World: Their Evolution, Behavior, and Ecology. The Journal of Wildlife Management, Vol. 64, No. 2, 606-607. Apr., 2000. Web. June 20, 2013.