Download Geology of the Buffalo Gap/ Coronado Camp area

Field trip to the Permian and
Cretaceous Rocks of the Callahan
Divide area south of Abilene
General Geology
• As we go south from Abilene we go into the
area of the Callahan Divide. Here we see
mesas capped with Cretaceous resistant
rocks as shown on the diagram in the next
slide.
Cross section of the local geology
Limestone of the
Fredericksburg Gp
N
Abilene
Clear Fork Shale
Antler Sand
S
Locality Sketch
Map
Rt277
Abilene
Buffalo
Gap Rd
3
1
Coron
-ado’s
Camp
2
Lake
Abilene
Rt.
89
Buffalo
Gap
Field trip
stops
Stop #1
• Shales of the Clear Fork Gp
• Permian age
• Probable environment of deposition floodplain
Gps coordinates:
N32deg 15.015min
W99deg 53.576min
Plant fossils in the reddish shales of
the Clear Fork Gp
Shales of the Clear Fork Gp, ruler is 1ft.long
Shales of the Clear Fork Gp breaking down to a
residual soil, green ruler is 1 ft. long
Lake Abilene
• This is a man made lake created in
order to provide a reliable water supply
for the city of Abilene
Photo take from:
N32deg 13.886min
W99deg 53.479min
Lake Abilene
Another view of Lake Abilene
Stop #2
• Antler Sand of the Trinity Gp
• Cretaceous
• Probable environment of deposition - beach
environment
GPS coord:
N32deg 14.896min
W99deg57.100min
Antler Sand along the highway
Antler Sand with GSA photo scale
Another view of the Antler Sand
with GSA photo scale
Antler Sand with car for scale
Stop #3
• Limestone unit of the Fredericksburg Gp
• Cretaceous age
• Probable Environment of Deposition shallow offshore marine
GPS coord:
N32deg 16.396min
W99deg 56.777min
Limestone of the Fredericksburg Gp
Another photo of the Fredericksburg Gp limestone
that sits on top of the Antler Sand
Remember
• Safety first and always on field trips
• These slides and other information give an
idea of the geology at various locations but
the best way to get to know it is to really
visit these sites in person - geologic
observations in the field form the raw data
on which the geosciences are based.
• A Reference follows on next page.
Reference
• 1. Taylor, Howard, 1978,Occurrence,
Quantity and Quality of Groundwater in
Taylor County, Texas. Texas Department of
Water Resources. Report 224.
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