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