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
Mostly sunny; warmer
Chance of showers; cooler
Mostly cloudy
Mostly cloudy; warmer
Partly cloudy
Partly cloudy
33° on Nov. 14, 2018, the coldest reading for this week of the year since 1941. Next is 34° in 1970.
Alton’s center stands about 160 ft above sea level. Within three miles the land runs from 140 ft to 190 ft, a difference of 50 ft: nearly flat ground.
Under the town center the state geologic map shows Dune sand sheet deposits, from the Holocene, less than 12,000 years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. 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: Holocene, less than 12,000 years old. About 7 mi of the line.
Clay, sandstone. Age: Miocene, 5.3 to 23 million years old. About 6 mi of the line.
Silt, sand, clay. Age: Pleistocene, less than 2.6 million years old. About 4 mi of the line.
Silt, sand. Age: Holocene, less than 12,000 years old. About 3 mi of the line.
Clay, silt. Age: Pleistocene, less than 2.6 million years old. About 2 mi of the line.
Silt, clay. Age: Holocene, less than 12,000 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. 1 smaller unit 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 Alton reaches the Gulf of America by way of the Arroyo Colorado: about 90 river miles.
55 miles of the trip are on the Arroyo Colorado.
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 hot semi-arid climate. Summer afternoons average 100° in August; winter nights fall to about 53° in January. About 22 inches of rain fall in a normal year.
On November 14 Alton normally reaches 80° and falls to 60°. The record high is 93°, in 1989; the record low 33°, in 2018. The most rain on this date, 0.20 in, fell in 1959.
Normals 1991–2020 and records since 1941 from the McAllen Area threaded record (Mcallen Miller International Airport, 9 miles south-southeast). NOAA, through RCC-ACIS.
