The Alton 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.
Partly cloudy
Partly cloudy
Mostly cloudy
Showers likely; cooler
Partly cloudy
Showers likely
Showers likely
76° on Nov. 12, 2015, the hottest reading for this week of the year since 1915. Next is 71° in 1999.
Alton’s center stands about 7,040 ft above sea level. Within three miles the land runs from 6,770 ft to 8,050 ft, a difference of 1,280 ft: steep hill country. The highest named summit within 15 miles is Black Butte, about 9,550 ft, 11 miles northeast.
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 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 6×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone-mudstone, sandstone. Age: Late Cretaceous, 72 to 94 million years old. About 11 mi of the line.
Limestone, mudstone. Age: Late Paleocene to Early Oligocene, 28 to 59 million years old. About 9 mi of the line.
Sandstone-mudstone. Age: Late Cretaceous, 72 to 84 million years old. About 2 mi of the line.
Unconsolidated. Age: Quaternary, less than 2.6 million years old. About 2 mi of the line.
Basalt. Age: Quaternary, less than 2.6 million years old. About 0.6 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.
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 Alton reaches the Gulf of California by way of the East Fork Virgin, the Virgin and the Colorado: about 660 river miles.
Lakes on the way: Lake Mead, 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 Alton; river miles along the main stem, rounded.
Alton has a dry-summer warm-summer continental climate. Summer afternoons average 85° in July; winter nights fall to about 18° in January. A normal year brings about 78 inches of snow; with the rain, that comes to about 17 inches of water.
On November 14 Alton normally reaches 52° and falls to 25°. The record high is 69°, in 1999; the record low 4°, in 1982. The most rain on this date, 0.59 in, fell in 1955.
Normals 1991–2020 and records since 1915 at Alton, here. NOAA, through RCC-ACIS.
