| and Cucharas Creek valley
James S. Aber |
|
| and Cucharas Creek valley
James S. Aber |
| Glaciation | Age Range* | Oxygen-isotope stage | Mid-continent correlation | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| pre-Bull Lake | 500,000-700,000 | | Independence | pre-Bull Lake
| 300,000 to 500,000
| pre-Illinoian | Bull Lake
| 130,000 to 300,000
| Illinoian | Pinedale
| 12,000-23,000
| Late Wisconsin | |
* Based on various radiometric and relative dating methods.
Aerial photograph of the Cuchara/Trinchera vicinity.
| View of the Culebra Range from the east. Trinchera Peak (TP) is highest mountain to left. The heads of three glaciated valleys are marked by asterisks (*). Position of the major moraine in the Cucharas Creek valley is indicated. Image date 6/03; © J.S. Aber |
The moraine at Blue and Bear Lakes is composed mainly of till, an unstratified and unsorted mixture of sand, gravel, silt, and clay sediment. Red and gray sandstone comprise the larger rock fragments, which are angular to subrounded in shape. Many bear striations, grooves, and other glacial markings. Numerous ridges, knobs, and kettle holes make for rough terrain within the moraine complex.
| Upper Blue Lake with Trinchera Peak in the left background. Blue Lake is a "kettle lake" in the moraine complex within the valley of Cucharas Creek. This moraine was constructed during a recessional phase of the Pinedale glaciation. Image date 6/99; © J.S. Aber |
| Steven Veatch demonstrates till on the valley side above Blue Lake. The till consists of red and gray sandstone fragments within a finer matrix. He points to a thin bed of sandy sediment (darker color) within the till. Image date 6/99; © J.S. Aber |
In the higher portions of the glacial valleys, till forms smaller recessional moraines. Erosional features include oversteepened bedrock steps, basins, cirques, and glacial pavements.
| Trinchera Peak as seen from the arete ridge that extends north from the peak. Trinchera Peak is a classic alpine horn that was eroded and steeped by glaciers on its sides. Note the near-vertical position of rock strata of the peak. Image date 5/02; © J.S. Aber |
| View eastward from Trinchera Peak with West Spanish Peak in the distance. The valley in the foreground is the headwaters of Cucharas Creek. Bedrock steps, moraines, and cirques attest to the glacial origin of landforms in the valley. A - end moraine in upper valley, B - lateral moraine in upper valley, C - Blue-Bear Lake moraine in lower valley. Image date 8/01; © J.S. Aber |
| Tiny cirque on the northeastern side of Trinchera Peak. Note the bowl-shaped basin of the cirque and the lake at the center. This cirque was formed by a small glacier that occupied the basin. Image date 8/01; © J.S. Aber |
| View from Trinchera Peak toward the northwest. Sierra Blanca Peak is visible on the horizon. Trinchero Creek valley in the foreground descends quite steeply from Trinchera Peak (see next image). Image date 8/03; © J.S. Aber |
| Floor of Trinchero Creek valley on northwest side of Trinchera Peak. Note the glacial landforms with a small lake dammed behind a moraine. Image date 8/03; © J.S. Aber |
| Periglacial features Trinchera vicinity |
In the alpine zone (above treeline), strong frost action and deep ground freezing have produced periglacial features, such as patterned ground and rock glaciers (Wallace and Lindsey 1996). These features are postglacial and presumably date from cold episodes in the latest Pleistocene and Holocene (see Table II).
| Glaciation Periglacial Episode | Age Range* | Period |
|---|---|---|
| Grenadier, Temple Lake Ptarmigan, Triple Lakes | 9000 to 10,000 | Younger Dryas Earliest Holocene |
| Minimal glaciation or periglacial phenomena | 8000 to 5000 | Altithermal Early to mid-Holocene |
| Audubon Rock glaciers | 2500 to 5000 | Early Neoglacial Late Holocene |
| Arapaho, Gannett Peak Rock glaciers | 120 to 400 | Little Ice Age Late Neoglacial |
* Based on various radiometric and relative dating methods.
| Overview of patterned ground on the crest of Trinchera Peak. Stones define a network of polygons. Orange survey flags mark a study grid. Image date 8/03; © J.S. Aber. |
| Jet Tilton demonstrates stone polygons on the crest of Trinchera Peak. Raised turf mounds are surrounded by shallow troughs filled with angular stones. Image date 8/01; © J.S. Aber. |
| Soil section in a turf mound of a typical stone polygon on Trinchera Peak. Well-developed A, B and C soil horizons indicate this feature has been stable for some time. Image date 8/03; © J.S. Aber. |
| Small rock glacier below a cliff of gray sandstone, Sangre de Cristo Formation, upper Cucharas Creek valley. The rock glacier has migrated in lobate form into a small cirque basin. Image date 8/01; © J.S. Aber. |
| Jet Tilton demonstrates the raised turf mound at the toe of a rock glacier in a small cirque basin, upper Cucharas Creek valley. Image date 8/01; © J.S. Aber. |
| Bighorn mountain sheep at the head of Cucharas Creek valley next to Trinchera Peak. Mountain sheep are common in the alpine zone of the Culebra Range. Vegetation here consists of low "cushion" plants that grow quite slowly. Image date 8/03; © J.S. Aber. |
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GO 547/ES 747 © J.S. Aber (2004).
Table I. Composite stratigraphy of Pleistocene glaciations in the southern Rocky Mountains, Colorado and northern New Mexico. Based on Richmond (1965, 1986) and Armour et al. (2002).
Table II. Composite stratigraphy of Holocene glaciations and periglacial episodes in the southern Rocky Mountains, Colorado and northern New Mexico. Based on Richmond (1986) and Armour et al. (2002).