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.
Mostly cloudy
Partly cloudy
Mostly sunny
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Mostly sunny; warmer
Partly cloudy
Showers likely; warmer
87° on Nov. 14, 1999, the hottest reading for this week of the year since 1902. Next is 82° in 2012.
Alton’s center stands about 1,650 ft above sea level. Within three miles the land runs from 1,600 ft to 1,800 ft, a difference of 200 ft: gently rolling country. The highest named summit within 15 miles is Round Mound, about 2,050 ft, 15 miles south.
Under the town center the state geologic map shows Alluvium (sand, silt, clay), from the Pleistocene to Holocene, less than 2.6 million years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 48×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Silt. Age: Pleistocene to Holocene, less than 2.6 million years old. About 13 mi of the line.
Shale, limestone. Age: Late Cretaceous, 66 to 100 million years old. About 7 mi of the line.
Sand, silt, clay. Age: Pleistocene to Holocene, less than 2.6 million years old. About 4 mi of the line.
Shale, chalk. Age: Late Cretaceous, 66 to 100 million years old. About 0.3 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 America by way of Crooked Creek, the South Fork Solomon, the Solomon, the Smoky Hill, the Kansas, the Missouri and the Mississippi: about 1,990 river miles.
Lake on the way: Waconda Lake.
1,170 miles of the trip are on the Mississippi.
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-summer humid continental climate. Summer afternoons average 93° in July; winter nights fall to about 14° in January. A normal year brings about 18 inches of snow; with the rain, that comes to about 29 inches of water.
On November 14 Alton normally reaches 56° and falls to 26°. The record high is 87°, in 1999; the record low −9°, in 1940. The most rain on this date, 0.93 in, fell in 1926.
Normals 1991–2020 and records since 1902 at Alton 2 SW, here. NOAA, through RCC-ACIS.
