geology of high point, n.c
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Geology of High Point, N.C. Linda Kennedy, Department of Geography, UNCG, July 2011. Geology of High Point, N.C. - PowerPoint PPT PresentationTRANSCRIPT
Geology of High Point, N.C.
Linda Kennedy, Department of Geography, UNCG, July 2011
Geology of High Point, N.C.
High Point is located on rock that formed during the Paleozoic Era (between 570 and 286 million years ago). Rock exposures are not typically common on the Piedmont because the bedrock is covered by a very thick mantle of soil.
However, Boulding Branch creek has eroded and removed enough soil in places to expose the underlying bedrock.
Geology of High Point, N.C.
Bedrock is exposed in BouldingBranch Creek, in at least three locations:
1.Bedrock Bridge
2.Two-Mile marker
3.Safe Haven
Two-mile marker
Andrew’s HS
Geology of High Point, N.C.
Location: Two Mile Marker
Bedrock exposedin middle of
creek
Geology of High Point, N.C.
What type of rock is exposed in Boulding Branch Creek?
How was the rock formed?
What has happened to the rock since it was first formed?
Rock Type
Andrew’s HS
BB Creek
Rock exposed in Boulding Branch creek is intrusivevolcanic rock that has beenlater subjected to stress, resulting in metamorphism.
P.A. Carpenter, III. 1982. Geologic Map of Region G, North Carolina. North Carolina Department of Natural Resources
Intrusive volcanic (igneous) rock
Rock Type
Rock Type
Intrusive volcanic (igneous) rock
• cools very slowly deep in the crust• relatively large mineral crystals have time to form – described as coarse grained• granite and diorite are examples of coarse grained intrusive volcanic (igneous) rock
Granite
Diorite
At a later date, the volcanic rock was exposed to extreme pressure/stress and temperatures,resulting in the recrystalization of minerals.
Rock Type
Metamorphism
Life History of Boulding Branch Rock
Formation of Pangea
The rocks exposed in Boulding Branch creek were originally
formed PRIOR to the formationof the supercontinent Pangea,
but are an important part of the Pangea story.
The Piedmont of North Carolinawas at the center of Pangea action!
North Carolina
Before Pangea
http://www.jan.ucc.nau.edu/~reb7/nam.html
485 Ma
The Iapetus Oceanonce separatedNorth America fromAfrica. It was theclosing of the IapetusOcean that resulted inthe formation ofPangea.
North Carolina looked verydifferent at that time. Neitherthe Piedmont nor the CoastalPlain existed.
As the ocean closed,a chain of volcanicislands graduallymoved toward NorthAmerica.
IapetusOcean
VolcanicChain
N.C.
Before Pangea
430 Ma 400 MaWhen they collided, a portion of the volcanic islands were accreted (scraped) onto the eastern edge of the North American continent.As the Iapetus continued to close, a small portion of continental
crust (a microcontinent) moved towards North America.
N.C.
Microcontinent
http://www.jan.ucc.nau.edu/~reb7/nam.html http://www.jan.ucc.nau.edu/~reb7/nam.html
Before Pangea
http://www.jan.ucc.nau.edu/~reb7/nam.html http://www.jan.ucc.nau.edu/~reb7/nam.html
345 Ma 315 Ma
N.C.
Some of the microcontinent was also accreted onto the eastern edge ofNorth America. Ongoing closure finally resulted in Africa colliding with the
North American continent.
N.C.
290 Ma
Pangea formed
Formation of Pangea
Volcanic island chainmoves westward.
Volcanic chain collidesand is accreted ontoeastern edge of N.A.microcontinent moveswestward.
Microcontinent collidesand is accreted ontoeastern edge of N.A.
African continentcollides with N.A.forming Pangea.
Rock of the Outer Piedmont
Formation of Outer PiedmontThe rocks underlying High Point began life asmagma that cooled deep in Earth’s crustbelow a chain of volcanic islands
The volcanic chain formed over a subductionzone located close to the eastern edge of theNorth American continent
The subduction occurring off the easterncoast accreted (scraped) some of the volcanic rocks onto the edge of the North American continent. The later collision of North America and Africa resulted in the formation of Pangea and the metamorphism of the accreted volcanic rock
Presently
Presently, Piedmont rock is being weathered,eroded, and ultimately transported to the
Atlantic Ocean where it is deposited as sediment.This sediment once compacted and cemented will
become the sedimentary rock of the future.
Examination of sediment in Boulding Branch Creekindicates that human manufactured particles of
glass and plastic are abundant, and it is thereforepossible that future sedimentary rock will contain
human made debris!
Resources
General
N.C. Department of Environment and Natural Resourceshttp://portal.ncdenr.org
United States Geological Survey (USGS)http://www.usgs.gov
N.C. Geological Surveyhttp://www.geology.enr.state.nc.us
USGS Studies in N.C.http://pubs.usgs.gov/fs/fs-033-96
Relief Map of North Carolinahttp://geology.com/shaded-relief/southeast.shtml
Lesson plans/Activities
Geosphere links for teachershttp://nesen.unl.edu/scienceresources/linksgepsphere.asp
Resources for K-12 Earth Science Educatorshttp://www.geosociety.org/educate/resources.htm
USGS resources for secondary schoolshttp://education.usgs.gov/common/secondary.htm
Mining Institutehttp://www.mii.org