The Blanca plate. Relief from Copernicus GLO-30; rivers and lakes from USGS NHD; watersheds from the USGS Watershed Boundary Dataset; roads and city limits from Census TIGER 2024.
Chance of showers
Mostly sunny; warmer
Partly cloudy
Chance of showers
Mostly sunny
Partly cloudy
Chance of showers
−13° on Nov. 15, 1985, the coldest reading for this week of the year since 1906. Next is −12° in 1940.
Blanca’s center stands about 7,760 ft above sea level. Within three miles the land runs from 7,690 ft to 8,140 ft, a difference of 450 ft: hilly country. The highest named summit within 15 miles is Blanca Peak, about 14,240 ft, 10 miles north.
Under the town center the state geologic map shows Unclassified surficial deposits and underlying Alamosa Fm in San Luis Valley (unconsolidated), from the Tertiary to Quaternary, less than 66 million years old.
The section below crosses 8 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 3×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Unconsolidated. Age: Tertiary to Quaternary, less than 66 million years old. About 7 mi of the line.
Andesite. Age: Late Eocene to Early Oligocene, 30 to 35 million years old. About 6 mi of the line.
Gneiss. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 4 mi of the line.
Gravel, unconsolidated. Age: Pleistocene, less than 0.5 million years old. About 2 mi of the line.
Siltstone, sandstone, conglomerate. Age: Miocene to Pliocene, 2.6 to 23 million years old. About 2 mi of the line.
Arkose, conglomerate, shale. Age: Carboniferous, 299 to 324 million years old. About 1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 2 smaller units along the line are not listed.
Heights from Copernicus GLO-90 (a surface model: it includes buildings and tree canopy); summits from USGS GNIS; rivers from USGS NHDPlus HR; rock from the USGS State Geologic Map Compilation.
Blanca has a cold semi-arid climate. Summer afternoons average 83° in July; winter nights fall to about −1° in January. A normal year brings about 28 inches of snow; with the rain, that comes to about 7 inches of water.
On November 14 Blanca normally reaches 49° and falls to 13°. The record high is 67°, in 2017; the record low −5°, in 1940. The most rain on this date, 0.54 in, fell in 1985.
Normals 1991–2020 and records since 1906 from the Alamosa Area threaded record (Alamosa-Bergman Field, 19 miles west, 220 ft lower). NOAA, through RCC-ACIS.
