Lincoln County Geology

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Lincoln County Geology

• By
• Steve Gurley and Allen Hubbard
• April 23, 2009

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Some Geologic Concepts

• Geologic time think in terms of millions and
  even billions of years. Earth about 4.5 billion
  years.
• Oldest rocks in Lincoln County 600 million years
• Youngest geologic materials are floodplain
  alluvium deposits and slope wash.
• Lincoln County and all the Piedmont and Blue
  Ridge have undergone millions of years of
  erosion.
• Rocks in Lincoln County have gone through various
  phases of metamorphism as a result of deep burial
  and/or earth movement (tectonics) associated with
  major mountain building episodes (orogenies).

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Overview

• Most of Lincoln County, like most of the Piedmont
  and Blue Ridge of NC, roots of old mountains
• Many of the rocks at surface today were several
  miles underground during mountain building
  episodes.
• Evidence of three major mountain building events
  in Lincoln County
• Taconic Orogeny (Tugaloo Terrane)
• Acadian Orogeny (Cat Square Terrane)
• Alleghenian Orogeny (Charlotte and Kings Mountain
  (?) Terranes)

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Overview (contd)

• Lincoln County in four geologic terranes
• Charlotte Eastern
• Kings Mountain? East and East Central
• Tugaloo North Central
• Cat Square Western

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Structure

• Central Piedmont Suture
• Kings Mountain Shear Zone (Central Piedmont
  Suture?)
• Newton Window and Brendle Creek Fault
• Eufola Fault
• Rock joints and fractures

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Rocks

• Charlotte Terrane
• Metamorphosed granite
• Metamorphosed diorite

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Rocks (contd)

• Kings Mountain Terrane
• Battleground Formation
• Quartzite (metamorphosed sandstone)
• Phyllite (metamorphosed siltstone)
• Schist (metamorphosed clay stone)
• High Shoals Granite
• Blacksburg Formation
• Quartzite
• Meta-Conglomerate
• Phyllite
• Schist

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Rocks (contd)

• Tugaloo Terrane
• Biotite gneiss (metamorphosed clayey sandstone)
• Hornblende gneiss (amphibolite)
• Garnet-quartz rock (gondite)

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Rocks (contd)

• Cat Square Terrane
• Walker Top Granite
• Toluca Granite
• Biotite gneiss (metamorphosed clayey sandstone)
• Sillimanite schist (metamorphosed clay stone and
  siltstone)
• The Great Dike

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Focus on Indian/Howards Creek Basins

• Tugaloo and Cat Square Terranes
• Landforms/topography
• Stream orientation
• Rappahannock/Tallapoosa Line
• Soils
• Generally deep, well drained, low pH red Piedmont
  clays
• Soils associated with darker rocks (amphibolites,
  diorites, etc.) generally have mixed clay
  mineralogy making them less suitable for on-site
  development

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Focus on Indian/Howards Creek Basins (contd)

• Environmental geology
• Groundwater geology
• Erosion susceptibility (clayey soils and deep
  saprolite)
• Water supply watershed (Indian Creek
  Cherryville and High Shoals)
• Mineral Resources
• Monazite (phosphate mineral containing
  radioactive thorium) in granites and biotite
  gneisses
• Spodumene (lithium mineral) in Cherryville
  Granite
• Sand in alluvial deposits along streams

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