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Pseudokarst Regions
(map)
Pseudokarst regions contain caves in rocks that are much
less soluble than limestone or that formed by means other than solution.
Small, isolated areas of East and South Texas contain small caves in sandstone
or sediments but are not detailed here.
1. Clastokarst
Two notable regions of clastokarst are known in Texas: Palo Duro Canyon
and Lajitas. Clastokarst is formed in clastics (sediments). In Palo Duro
Canyon, caves have formed by suffosion (piping of sediments) along the
contact of steeply sloping landslides on the canyon walls (e.g., Catarina-Confusion
Cave Complex, Randall County). Similar caves apparently exist at the related
Caprock Canyons State Park, Briscoe County. At Lajitas, a small area of
upper Cretaceous or lower Tertiary clay is rife with sinkholes and small
caves; it remains unstudied.
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Passage at the bottom of Mount Emory Cave, Big Bend National Park, Brewster County, Texas.
- photo George Veni
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2. Igneous and metamorphic rocks
Caves are known from granite, marble, rhyolite, and lava. The caves are
generally so isolated that they do not comprise a region. The exception
is Enchanted Rock, centrally located in the Llano Region, where many caves
are known under and between collapse blocks; some caves exhibit enlargement
by "grusification," dissolution-enhanced erosion of the granite
(e.g., Enchanted Rock Cave, Llano County). |
