From Persimmon Gap to Boquillas Canyon, Part 14: Structural Geology Illustrated | Boquillas Canyon, Big Bend National Park, USA, and Mexico
Looking north-northeastward from just downstream from the mouth of Boquillas Canyon.
Its upper half still glowing in the late-afternoon sun, the Mexican wall of the Rio Grande's Boquillas Canyon reveals its classic and oft-cited example of crustal disturbance.
Besides being a showcase of marine-carbonate rock deposition in the Cretaceous and extensive volcanic activity in the Tertiary, Big Bend National Park has much to teach the student of structural geology.
Thanks to the Laramide Orogeny and the Basin-and-Range phase that has followed it, this federal preserve and the adjoining Big Bend Ranch State Park contain numerous visible examples of folding and faulting in the Earth's crust.
The feature so beautifully displayed here is a normal fault in the Cretaceous Santa Elena Limestone. It's outlined by the diagonal trace in the center portion of the photo.
The mass of rock to the left of the trace, the headwall, has slid downward along it, just as gravity would seem to dictate. The section to the right is the footwall.
To see the other photos and descriptions in this set and my other Big Bend series, visit my my From Persimmon Gap to Boquillas Canyon album.
From Persimmon Gap to Boquillas Canyon, Part 14: Structural Geology Illustrated | Boquillas Canyon, Big Bend National Park, USA, and Mexico
Looking north-northeastward from just downstream from the mouth of Boquillas Canyon.
Its upper half still glowing in the late-afternoon sun, the Mexican wall of the Rio Grande's Boquillas Canyon reveals its classic and oft-cited example of crustal disturbance.
Besides being a showcase of marine-carbonate rock deposition in the Cretaceous and extensive volcanic activity in the Tertiary, Big Bend National Park has much to teach the student of structural geology.
Thanks to the Laramide Orogeny and the Basin-and-Range phase that has followed it, this federal preserve and the adjoining Big Bend Ranch State Park contain numerous visible examples of folding and faulting in the Earth's crust.
The feature so beautifully displayed here is a normal fault in the Cretaceous Santa Elena Limestone. It's outlined by the diagonal trace in the center portion of the photo.
The mass of rock to the left of the trace, the headwall, has slid downward along it, just as gravity would seem to dictate. The section to the right is the footwall.
To see the other photos and descriptions in this set and my other Big Bend series, visit my my From Persimmon Gap to Boquillas Canyon album.