James S. Aber
|Cucharas Pass||Raton Basin|
|Culebra Range||Trinchera Peak|
Colorado highway 12 follows the Cuchara River valley from the north and crosses the pass into the Purgatoire drainage basin to the south. Designated as the Highway of Legends, this route is said to involve hidden cities and buried gold. Cuchara is the Spanish word for spoon. According to legend, the valley was formed when a giant laid down his spoon in a rain, which left a lasting impression. Culebra is the Spanish word for snake. Regardless of the legendary aspects, the highway does provide excellent access to higher terrain in vicinity of Spanish Peaks and the Culebra Range.
East and north of Cucharas Pass
The region east of Cucharas Pass is part of the Raton Basin. Eastward from the pass, upper
Cretaceous and lower Tertiary strata are exposed along the county road to Cordova Pass.
Beginning at Cucharas Pass, upper Cretaceous strata are present,
and progressively younger strata are encountered along the county road to the east. These
strata are described below in ascending order (from oldest to youngest).
Conglomerate of Cordova Pass is metamorphosed adjacent to a dike in the left foreground. Trinchera Peak is visible in the right background. Cordova Pass, June 2003 © J.S. Aber. Sandstone facies of the Cuchara Formation seen at the golf course in La Veta. Poorly consolidated arkosic sandstone and pebbly sandstone outcrop in rounded blocks that weather rapidly. Nov. 2008 © J.S. Aber.
|View northeastward across the Cuchara Valley with West Spanish Peak in the right distance. The White Peaks are a thick sill injected into upper Cretaceous Pierre Shale that stands vertically on the western flank of the Raton Basin. In front of White Peaks and lower is the Dakota hogback, comprised of lower Cretaceous sandstones, also standing in vertical position. Image date 6/03; © J.S. Aber.|
|Late autumn view from Spring Creek Trail above Cuchara, looking eastward. WSP = West Spanish Peak. NWP = North White Peak, MWP = Middle White Peak, SWP = South White Peak. For description of the Dakota, see Monument Lake. Image date 11/03; © J.S. Aber.|
West of Cucharas Pass
The foothills of Culebra Range begin immediately west of Cucharas Pass. The foothills ascend
steeply westward to the crest of the range, in which the peaks exceed 4000 m (13,000 feet)
elevation. The entire sequence, from the foothills to range crest, is contained in the Sangre
de Cristo Formation. As the name suggests, most of these rocks have blood-red color.
|View westward from near Cucharas Pass toward the Culebra Range on the horizon. Trinchera Peak is visible to left side of scene. It reaches 4120 m (13,517 feet) elevation, the highest peak in the northern part of the Culebra Range. In the middle distance is the valley of Cucharas Creek, which drains from Trinchera Peak. Image date 6/03; © J.S. Aber|
|Roadcut exposure of the Sangre de Cristo Formation on Colorado highway 12. Redbeds dip steeply to the east (left) at this location. Image date 6/99; © J.S. Aber.|
The Sangre de Cristo Formation represents the sedimentary deposits of the Ancestral Rocky Mountains. Uplifted in the same location as the modern Culebra Range, these older mountains underwent erosion, and the resulting sediment accumulated as alluvial fans in an adjacent basin. Conglomerate beds suggest that the mountain source was not far from the depositional site of the Sangre de Cristo Formation. The bright red color is common for Permian strata of the southern plains region, known as the "Permian basin." Similar rocks can be seen in New Mexico, Texas, Oklahoma, and Kansas. Uplift of the Ancestral Rockies took place at the same time as the Ouachita orogeny in Arkansas, Oklahoma and Texas.
Trinchera Peak marks the crest of the northern portion of the Culebra Range. It is composed of vertical to slightly overturned, gray, quartzose sandstone of the basal Sangre de Cristo Formation. The erosional resistance of the quartzose sandstone accounts for its topographic prominence at the ridge crest. The western flank of the Culebra Range continues with Madera Formation overthrust by crystalline basement rocks, which can be seen clearly from the crest of the range.
|Gray sandstone of the basal Sangre de Cristo Formation stand in near-vertial position beneath Trinchera Peak. Note the red rocks on east (left) flank of peak; this is a fault zone and gray sandstone is repeated farther to left. Image date 8/03; © J.S. Aber.|
|View northward from Trinchera Peak along the western side of the Culebra Range. The light gray strata in scene center comprise the Whiskey Creek Limestone Member of the Madera Formation. Image date 8/01; © J.S. Aber.|
|View westward from the crest of the Culebra Range. The deformed gray strata are part of the Madera Formation, and the reddish zone at top of section is crystalline rock (see next image). Image date 8/03; © J.S. Aber.|
|Tilted and deformed strata of the Madera Formation (gray) are capped by reddish crystalline rocks. The contact between gray and red rocks marks the Culebra Thrust Fault (Wallace and Lindsey 1996). Image date 8/03; © J.S. Aber.|
|View from the west with the Culebra Range and Trinchera Peak (center) on the eastern horizon. Notice how the clouds are a subtle reflection of ridge crest topography. Image date 3/02; © J.S. Aber.|
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GO 547/ES 747 © J.S. Aber (2008).