The Fort Madison 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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2° on Nov. 17, 1959, the coldest reading for this week of the year since 1893. Next is 6° in 1986.
Fort Madison’s center stands about 530 ft above sea level. Within three miles the land runs from 510 ft to 730 ft, a difference of 220 ft: rolling country. The highest named summit within 15 miles is Gittings Mound, about 760 ft, 14 miles east.
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 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.
Limestone. Age: Middle Mississippian, 331 to 347 million years old. About 10 mi of the line.
Dolostone, limestone. Age: Middle Mississippian to Late Mississippian, 324 to 347 million years old. About 4 mi of the line.
Dolostone, limestone, siltstone. Age: Early Mississippian, 347 to 359 million years old. About 3 mi of the line.
Dolostone, limestone. Age: Early Mississippian to Middle Mississippian, 331 to 359 million years old. About 3 mi of the line.
Shale, siltstone. Age: Late Devonian, 359 to 374 million years old. About 2 mi of the line.
Limestone. Age: Early Mississippian to Middle Mississippian, 331 to 359 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.
A raindrop that lands in Fort Madison reaches the Gulf of America by way of Dry Creek and the Mississippi: about 1,350 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Fort Madison; river miles along the main stem, rounded.
Fort Madison has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 17° in January. A normal year brings about 18 inches of snow; with the rain, that comes to about 39 inches of water.
On November 14 Fort Madison normally reaches 50° and falls to 33°. The record high is 74°, in 1971; the record low 10°, in 1976. The most rain on this date, 2.38 in, fell in 1985.
Normals 1991–2020 and records since 1893 at Fort Madison, here. NOAA, through RCC-ACIS.
