Spanish Peaks Dyke
I saw this fine example of part of a volcanic dyke in late-afternoon sunshine whilst driving up State Route 12 near the Cucharas River just south of La Veta in southern Colorado. It is one of dozens of dykes that radiate from West Spanish Peak towering up in the background.
Two peaks, East Spanish Peak at 3,867m (just off-shot to the left) and West Spanish Peak at 4,155m, are east of, and separate from, the Culebra Range of the Sangre de Cristo Mountains. Both are higher than any point in the United States farther east. They are 164 km due south of (and can be seen from) Colorado Springs and were an important landmark on the Santa Fe Trail, being the first sighting of the Rocky Mountains for travellers on the trail. The mountains can be seen from points up to 160 km east on the Great Plains.
The Spanish Peaks were formed by two separate shallow (or hypabyssal) igneous intrusions during the Late-Oligocene epoch of the Paleogene Period. West Spanish Peak is an older (roughly 24.5 million-year-old) quartz syenite. East Spanish Peak is about 23.4 million years old and is composed of a granodiorite porphyry surrounded by a more aerially-extensive exposure of granite porphyry. The granite porphyry represents the evolved upper portion of the magma chamber while the interior granodiorite porphyry is exposed by erosion at the summit.
The Spanish Peaks were designated a National Natural Landmark in 1976 as two of the best known examples of igneous dykes. These vertical granite formations were formed by molten rock several thousand feet underground, below and among many layers of sedimentary rock. Over time, the ground rose and the softer rock eroded away, exposing these igneous intrusions.
Spanish Peaks Country has three unique sets of dykes. One emanates radially from the West Spanish Peak, another set emanates radially from Silver Mountain, and a third set crosses the landscape roughly 80˚ east of north. The dykes in this third set are roughly parallel to one another, are the longest and oldest, and were formed around the same time as the Sangre de Cristo Uplift - the event that pushed up the Sangre de Cristo Mountains 27 million years ago.
Spanish Peaks Country’s dykes are granite. In the western portions of Las Animas and Huerfano Counties, there are some uplifted stone walls of the Dakota Formation. They look like granite but are actually compressed, durable sandstone parts of a formation running from Canada to Mexico along the Front Range and eastwards.
Scanned from a negative.
Spanish Peaks Dyke
I saw this fine example of part of a volcanic dyke in late-afternoon sunshine whilst driving up State Route 12 near the Cucharas River just south of La Veta in southern Colorado. It is one of dozens of dykes that radiate from West Spanish Peak towering up in the background.
Two peaks, East Spanish Peak at 3,867m (just off-shot to the left) and West Spanish Peak at 4,155m, are east of, and separate from, the Culebra Range of the Sangre de Cristo Mountains. Both are higher than any point in the United States farther east. They are 164 km due south of (and can be seen from) Colorado Springs and were an important landmark on the Santa Fe Trail, being the first sighting of the Rocky Mountains for travellers on the trail. The mountains can be seen from points up to 160 km east on the Great Plains.
The Spanish Peaks were formed by two separate shallow (or hypabyssal) igneous intrusions during the Late-Oligocene epoch of the Paleogene Period. West Spanish Peak is an older (roughly 24.5 million-year-old) quartz syenite. East Spanish Peak is about 23.4 million years old and is composed of a granodiorite porphyry surrounded by a more aerially-extensive exposure of granite porphyry. The granite porphyry represents the evolved upper portion of the magma chamber while the interior granodiorite porphyry is exposed by erosion at the summit.
The Spanish Peaks were designated a National Natural Landmark in 1976 as two of the best known examples of igneous dykes. These vertical granite formations were formed by molten rock several thousand feet underground, below and among many layers of sedimentary rock. Over time, the ground rose and the softer rock eroded away, exposing these igneous intrusions.
Spanish Peaks Country has three unique sets of dykes. One emanates radially from the West Spanish Peak, another set emanates radially from Silver Mountain, and a third set crosses the landscape roughly 80˚ east of north. The dykes in this third set are roughly parallel to one another, are the longest and oldest, and were formed around the same time as the Sangre de Cristo Uplift - the event that pushed up the Sangre de Cristo Mountains 27 million years ago.
Spanish Peaks Country’s dykes are granite. In the western portions of Las Animas and Huerfano Counties, there are some uplifted stone walls of the Dakota Formation. They look like granite but are actually compressed, durable sandstone parts of a formation running from Canada to Mexico along the Front Range and eastwards.
Scanned from a negative.