A Magic Circle Called the Solitario, Part 1: The Western Flank of the Solitario Uplift | Big Bend Ranch State Park, Texas, USA
Among my greatest days of exploration was the one devoted to getting into the Solitario and then examining its rarely seen interior. It may not be all that many miles from various human settlements, but no matter. This aptly named place generates a greater sense of remoteness than anywhere else I've been. And yet it also struck me, perhaps because of its overall shape, as being the center of things. It has become my personal version of the ancient Greeks' Omphalos.
The photo above might not be the prettiest or most immediately eye-catching landscape shot, but it sets the scene for those that follow. It faces SE, more or less, and shows the western outer rampart of the Solitario from the outside. In the foreground stretch darker-toned lava and pyroclastic-ash flows of various compositions, all mapped as Oligocene in age.
As is apparent when seen on a map, the Solitario forms a remarkable bull's-eye structure about 9 mi (14.5 km) in diameter. It resembles other circular features now known to be astroblemes (meteorite impact sites). The outer enclosing ring consists of flatirons of Cretaceous limestone. Inside them stand ridges and valleys composed of older, Paleozoic strata.
Also present within are igneous-rock outcrops that reveal that the Solitario is actually not an impact structure: the forces that contorted the crust and created such a complicated geologic legacy largely came from below. Instead, the Solitario is a laccolithic dome and collapsed volcano.
That dome began to form when a lens-shaped mass of magma thrust up and fractured both the Cretaceous units visible here and older Paleozoic strata already deformed by earlier tectonic episodes. This intrusion happened about 35.4 Ma ago, late in the Eocene epoch.
But a substantial portion of the magma also made its way to the surface. There it erupted in spectacular fashion and blanketed the region with at least fifteen times as much volcanic ash as was released by Mount St. Helens in 1980.
Once its subterranean magma chamber was depleted, the volcano collapsed to form a large, bowllike depression called a caldera. These events and subsequent debris fill and erosion created the Solitario's current, fascinating form.
For more on this amazing locale, see the other photos and descriptions in my A Magic Circle Called the Solitario album.
A Magic Circle Called the Solitario, Part 1: The Western Flank of the Solitario Uplift | Big Bend Ranch State Park, Texas, USA
Among my greatest days of exploration was the one devoted to getting into the Solitario and then examining its rarely seen interior. It may not be all that many miles from various human settlements, but no matter. This aptly named place generates a greater sense of remoteness than anywhere else I've been. And yet it also struck me, perhaps because of its overall shape, as being the center of things. It has become my personal version of the ancient Greeks' Omphalos.
The photo above might not be the prettiest or most immediately eye-catching landscape shot, but it sets the scene for those that follow. It faces SE, more or less, and shows the western outer rampart of the Solitario from the outside. In the foreground stretch darker-toned lava and pyroclastic-ash flows of various compositions, all mapped as Oligocene in age.
As is apparent when seen on a map, the Solitario forms a remarkable bull's-eye structure about 9 mi (14.5 km) in diameter. It resembles other circular features now known to be astroblemes (meteorite impact sites). The outer enclosing ring consists of flatirons of Cretaceous limestone. Inside them stand ridges and valleys composed of older, Paleozoic strata.
Also present within are igneous-rock outcrops that reveal that the Solitario is actually not an impact structure: the forces that contorted the crust and created such a complicated geologic legacy largely came from below. Instead, the Solitario is a laccolithic dome and collapsed volcano.
That dome began to form when a lens-shaped mass of magma thrust up and fractured both the Cretaceous units visible here and older Paleozoic strata already deformed by earlier tectonic episodes. This intrusion happened about 35.4 Ma ago, late in the Eocene epoch.
But a substantial portion of the magma also made its way to the surface. There it erupted in spectacular fashion and blanketed the region with at least fifteen times as much volcanic ash as was released by Mount St. Helens in 1980.
Once its subterranean magma chamber was depleted, the volcano collapsed to form a large, bowllike depression called a caldera. These events and subsequent debris fill and erosion created the Solitario's current, fascinating form.
For more on this amazing locale, see the other photos and descriptions in my A Magic Circle Called the Solitario album.