The Armstrong 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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3.57 inches of rain fell in two days, the most for this week of the year since records began in 1946. The next wettest, 3.24 inches, fell in 1985.
Armstrong’s center stands about 840 ft above sea level. Within three miles the land runs from 690 ft to 880 ft, a difference of 190 ft: gently rolling country.
Under the town center the state geologic map shows Marmaton Group (limestone, shale), from the Carboniferous, 299 to 324 million years old.
The section below crosses 3 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, shale. Age: Carboniferous, 299 to 324 million years old. About 14 mi of the line.
Shale, sandstone, siltstone. Age: Carboniferous, 299 to 324 million years old. About 6 mi of the line.
Clay, silt, sand. Age: Holocene, less than 12,000 years old. About 4 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 Armstrong reaches the Gulf of America by way of Batts Creek, Doxies Creek, the Little Chariton, the Missouri and the Mississippi: about 1,410 river miles.
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 Armstrong; river miles along the main stem, rounded.
Armstrong has a hot-summer humid continental climate. Summer afternoons average 88° in July; winter nights fall to about 18° in January. About 40 inches of rain fall in a normal year.
On November 14 Armstrong normally reaches 54° and falls to 33°. The record high is 81°, in 1999; the record low 5°, in 1986. The most rain on this date, 1.02 in, fell in 1985.
Normals 1991–2020 and records since 1946 at Salisbury, 12 miles north-northwest, 110 ft lower. NOAA, through RCC-ACIS.
