The Great Smokey Mountain National Park is part of the Blue Ridge Mountains, a division of the larger Appalachian chain; it is located on the border between Tennessee and North Carolina at 35°41′0″N 83°32′0″W. It encompasses 814 square miles making it one of the largest protected areas east of the Mississippi river. The mountain building process began over a billion years ago making these mountains some of the oldest on earth. To many, the geological features may not be noticeable. A naturalist from the park once exclaimed "what geology ... we don't actually have any in this park!". What he meant was that the geological features were not obvious in the great smokey mountains national park. The mountains are a product of uplift and prolonged erosion. Moist air from the gulf of Mexico helped create dense forests and a smokey haze cover many of the geological features. Below is a map pinpointing the location of the smokey mountains between North Carolina and Tennessee.
Foremost, after forming a basement complex, the major geological forming event was the deposition of the Ocoee supergroup. The Ocoee Supergroup contains a number of fossils including tribolites, bryozoans, ostracodes, pelmatozoans, algae, and agglutinated forrminifers; it indicates a Silurian or younger age. The low-grade metamorphic rock of the walden creek group has helped date the park. This data contradicts older ideas that the Walden Creek Group dated to the Neoproterozoic age. This shows an example of how the fossil record is used in a relative dating method to determine the age of rock.
Tribolite fossils as shown in the picture below one of the most common fossils found in the park The tribolites made their first appearance during the early cambrian era. They finally died out in the permian 250 mya. There were 17,000 species of trilobites during the paleozoic time. The numerous fossils available have helped date the great smokey mountains.
Foremost, after forming a basement complex, the major geological forming event was the deposition of the Ocoee supergroup. The Ocoee Supergroup contains a number of fossils including tribolites, bryozoans, ostracodes, pelmatozoans, algae, and agglutinated forrminifers; it indicates a Silurian or younger age. The low-grade metamorphic rock of the walden creek group has helped date the park. This data contradicts older ideas that the Walden Creek Group dated to the Neoproterozoic age. This shows an example of how the fossil record is used in a relative dating method to determine the age of rock.
Tribolite fossils as shown in the picture below one of the most common fossils found in the park The tribolites made their first appearance during the early cambrian era. They finally died out in the permian 250 mya. There were 17,000 species of trilobites during the paleozoic time. The numerous fossils available have helped date the great smokey mountains.
The next major process which occurred was the crustal rifting and deposition of Paleozoic rock causing sentiments to collect and creating thousands of feet of oceanic sedimentary rock. Sentiments collected in an oceanic trench are shown in the picture below.
The majority of the rocks in the Great Smokey Mountains were formed by accumulations of clay, silt, sand, gravel, and minor amounts of calcium carbonate in flat-lying layers occurring over millions of years. The younger rocks of sedimentary origin formed during the Paleozoic Era, 450 to about 545 million years ago. The oldest sedimentary rocks were formed during the Proterozoic Era some 800-545 million years ago. Vast amounts of unconsolidated clay, silt, sand, and pebbles were washed down into lowland basins from adjacent highlands during that time.
Rocks of the old highlands were over one billion years old, and were similar to the ancient granite and gneiss found in the southeastern parts of the park. These early sites of ocean bottom deposition were formed along the ancient margin of the North American continent as an older and larger supercontinent broke apart.
Igneous rocks are present but only a limited amount can be found in the park. The two main igneous rocks found are granites and gneiss. Granites usually have a medium to coarse-grained texture. Gneiss rocks are usually medium to coarse-foliated and largely recrystallized. They often have large quantities of minerals including mica and chlorides.
A strike-slip fault is where the two forces move parallel to each other as shown below.
The majority of the rocks in the Great Smokey Mountains were formed by accumulations of clay, silt, sand, gravel, and minor amounts of calcium carbonate in flat-lying layers occurring over millions of years. The younger rocks of sedimentary origin formed during the Paleozoic Era, 450 to about 545 million years ago. The oldest sedimentary rocks were formed during the Proterozoic Era some 800-545 million years ago. Vast amounts of unconsolidated clay, silt, sand, and pebbles were washed down into lowland basins from adjacent highlands during that time.
Rocks of the old highlands were over one billion years old, and were similar to the ancient granite and gneiss found in the southeastern parts of the park. These early sites of ocean bottom deposition were formed along the ancient margin of the North American continent as an older and larger supercontinent broke apart.
Igneous rocks are present but only a limited amount can be found in the park. The two main igneous rocks found are granites and gneiss. Granites usually have a medium to coarse-grained texture. Gneiss rocks are usually medium to coarse-foliated and largely recrystallized. They often have large quantities of minerals including mica and chlorides.
Later, due to tectonic plate activity, the super continent of Pangea was formed. This the start to uplift during the Paleozoic era. The great smokies became the crest of a major mountain belt stretching across Pangaea.
The Alleghenian orgeny is a mountain forming event occuring 300-350 mya during the Carboniferous period. When the continents of Africa and North America collided it exerted massive stress making whattoday we call the Eastern Seaboard. There was a transfer of igneous and sedimentary rock into metamorphic due to the collision. These concurrences caused thrust faults and some strike-slip faults as well as folding. It is possible that at the peak of mountain building, the Appalachians could have been much higher, perhaps even high than present day Himalaya. The stresses caused faults called thrust faults and strike-slip faults are shown below. A thrust fault is a type of fault, or break in the Earth's crust across which there has been relative movement, in which rocks of lower stratigraphic position are pushed up and over higher strata. They are often recognized because they place older rocks above younger.
A strike-slip fault is where the two forces move parallel to each other as shown below.
Data by the U.S. Geological survey shows that the orogenic crust was formed after a crustal magma source. Orogeny refers to the forces and events which deformed the earth and this caused by tectonic plate movement. This created orgenic belts of deformed rocks.
The last process involved in forming the great smokey mountains was erosion which uncovered many of the older rocks. Erosion helped shape the ridges and valleys and uncovered many of the older rocks. This occurred during the mesozoic time and erosion continued throughout Cenozoic time. This shaping the mountains closely to their current form today.
Noting on a few of the key features in the park. The most visited location in the smokies is Clingmans Dome, it consists of lightly metamorphosized rock, and much of this which is Sandstone. These sedimentary rock types are most noticeable on rocky outcrops and in large boulder piles. Clingmans Dome is the highest mountain in the smokies, it has an elevation of 6,643 feet, and is the highest point of the 2,174 mile Appalachian trail. Below is a picture of the sandstone which is visible on the bank of east creek within the park.
Next, here is a structure map of Cades Cove in the Great Smoky Mountains National Park, another attraction in the park. Cades cove shows a thrust sheet that displays the rocks beneath the sheet. It shows a window within the Proterozoic Ocoee rocks where Paleozoic rocks of the Ordovician Knox Group are exposed.
Works Cited
Great Smokey Mountains A Visitors Guide. Great Smokey Mountains. , 2011. Web. 14 Feb 2011. <http://www.smokymountainsvisitorsguide.com/index.html>.
Harris, Ann, Ether Tuttle, and Sherwood Tuttle . Great Smokey Mountains National Park. Geology of National Parks 6th Edition. Dubuque: Kendal and Hunt Publishing Company, 2009. 821-834.
A Guide to the Orders of Trilobites . Web. 14 Feb 2011. <http://www.trilobites.info/>
King , Phillip, and Arthur. "The Great Smoky Mountains-Their Geology and Natural History." Scientific Monthly 71.1 n. pag. Web. 14 Feb 2011.
United States Department of the Interior. Great Smokey Mountains. , 2011. Web. 14 Feb 2011. <http://www.nps.gov/grsm/index.htm>.
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