La Veta Pass is an important transportation route across the Sangre de Cristo Mountain range in southern Colorado. The pass actually consists of two different modern routes--one followed by the railroad and the other for U.S. highway 160, plus an older route through the ghost town of La Veta Pass. Highest elevation on the highway route is 2869 m (9410 feet). Directly west of the pass is Blanca Peak at 4372 m (14,340 feet) elevation, the highest peak in this portion of the Sangre de Cristo Range. The name La Veta means "the vein" and may refer to gold veins in the vicinity.
||La Veta Pass and|
James S. Aber
A series of intrusive bodies is located near the pass, including Mount Maestas, Rough Mountain, Sheep Mountain, Little Sheep Mountain, and Silver Mountain. The latter is located in the Raton Basin, northeast of the pass. Silver Mountain is the center of a radial dike complex, similar to but smaller than West Spanish Peak. The intrusion of Silver Mountain is considered to be slightly older than Spanish Peaks (Penn and Lindsey 1996). The other mountains--Maestas, Rough, Sheep, and Little Sheep--represent magma that intruded along one of the main faults on the eastern margin of the Sangre de Cristo Mountains (Chronic 1980). The intrusive rocks form a linear chain of ridges extending to the north. Mount Maestas is composed of microgranite, which forms the bare, domelike mountain top visible from the highway.
|Winter view of Mount Maestas (right) and La Veta Pass (center)|
as seen from the southeast. Image date 01/07, © J.S. Aber.
||View east toward Rough Mt. and Mount Maestas. Note the rounded, completely bare appearance of the intrusive rocks that form the peaks. U.S. highway 160 crosses the bottom of the scene. Image date 3/02, © J.S. Aber.|
||Closeup view of Mount Maestas. A body of dark rock (shale) is exposed in the notch between Mount Maestas and Rough Mt. (see arrow). A rock glacier is also present in this notch (Peterson 1971). Image date 6/99, © J.S. Aber.|
Along the southern flank of Mount Maestas, the highway cuts through the typical sequence of sedimentary strata that form the eastern margin of the Sangre de Cristo foothills. A parking area and roadside marker are located where the highway crosses upper Cretaceous and lower Tertiary formations. However, the Purgatory/Dakota hogback is not present here. To the west, a thick sequence of redbeds is exposed along the highway up to and across the pass summit. These redbeds are the Sangre de Cristo Formation of Pennsylvanian and lower Permian age--see Cucharas Pass for more about these redbeds.
||View north toward North La Veta Pass. Typical red color of the Sangre de Cristo Formation is visible in the roadcut to lower-right (1). A bleached zone of buff-colored sandstone occurs to the left (2). This unusual color may be associated with hydrothermal alteration and gold deposits in Rough Mt. Image date 3/02, © J.S. Aber.|
Descending from La Veta Pass to the west, several rock formations can be seen along the highway
(based on Chronic 1980).
- Sangre de Cristo Fm. -- From the pass crest westward to mile marker 276. Soft
red shale, sandstone and conglomerates of Pennsylvanian and early Permian age. Blue on
- Pennsylvanian strata -- Mile marker 276 to 273. Gray, fossiliferous sandstone,
shale, and limestone. Basal portion of the Sangre de Cristo Formation and underlying Madera
Formation. Blue on geologic map. Small Tertiary intrusions are
- Proterozoic rocks -- Mile marker 273 to 268. Crystalline metamorphic rocks--gneiss,
schist, quartzite and conglomerate. Middle Proterozoic, 1.7 to 1.8 billion years old. Epidote
mineralization on some fracture surfaces took place in connection with Tertiary igneous
activity. Gray (Xm) on geologic map.
- San Luis volcanic rocks -- West of mile marker 268. Lavender and purple volcanic
rocks associated with the San Luis volcanic field of Oligocene age. Andesite and latite
lava, breccia, tuff, and conglomerate. Brown (Tov) on geologic map. These rocks mark the eastern margin of the Rio Grande rift system.
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GO 547/ES 747 © J.S. Aber (2007).