The Bluff 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.
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8° on Nov. 12, 1950, the coldest reading for this week of the year since 1911. Next is 10° in 1975.
Bluff’s center stands about 4,330 ft above sea level. Within three miles the land runs from 4,290 ft to 4,950 ft, a difference of 660 ft: hilly country. The highest named summit within 15 miles is Hogan Mesa, about 5,690 ft, 9 miles southeast.
Under the town center the state geologic map shows Alluvium and colluvium (unconsolidated), from the Quaternary, less than 2.6 million years old.
The section below crosses 10 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 14×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sand. Age: Quaternary, less than 2.6 million years old. About 11 mi of the line.
Sandstone. Age: Middle Jurassic to Late Jurassic, 145 to 175 million years old. About 4 mi of the line.
Sandstone. Age: Late Pennsylvanian to Permian, 273 to 307 million years old. About 4 mi of the line.
Unconsolidated. Age: Quaternary, less than 2.6 million years old. About 2 mi of the line.
Arenite. Age: Early Jurassic, 175 to 202 million years old. About 2 mi of the line.
Sandstone-mudstone. Age: Late Jurassic, 145 to 164 million years old. About 0.7 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 4 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.
A raindrop that lands in Bluff reaches the Gulf of California by way of the San Juan and the Colorado: about 990 river miles.
Lakes on the way: Lake Mead, Lake Powell, Lake Mohave and Lake Havasu.
290 miles of the trip are on the Colorado.
Seldom reaches the sea. Dams and canals now take nearly all of the Colorado before its old delta in Mexico.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Bluff; river miles along the main stem, rounded.
Bluff has a cold desert climate. Summer afternoons average 96° in July; winter nights fall to about 20° in January. A normal year brings about 7 inches of snow; with the rain, that comes to about 7 inches of water.
On November 14 Bluff normally reaches 56° and falls to 27°. The record high is 70°, in 1963; the record low 10°, in 1975. The most rain on this date, 0.34 in, fell in 1968.
Normals 1991–2020 and records since 1911 at Bluff, here. NOAA, through RCC-ACIS.
