The Arma 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.
Sunny
Partly cloudy
Sunny
Sunny
Partly cloudy
Partly cloudy
Partly cloudy
81° on Nov. 12, 1989, the hottest reading for this week of the year since 1957. Next is 81° in 1999.
Arma’s center stands about 1,010 ft above sea level. Within three miles the land runs from 890 ft to 1,020 ft, a difference of 130 ft: gently rolling country.
Under the town center the state geologic map shows Marmaton Group (shale, limestone, sandstone), 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.
Sandstone, shale. Age: Carboniferous, 299 to 324 million years old. About 20 mi of the line.
Shale, limestone, sandstone. Age: Carboniferous, 299 to 324 million years old. About 4 mi of the line.
Sand, silt, clay. Age: Pleistocene to Holocene, less than 2.6 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.
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 Arma reaches the Gulf of America by way of First Cow Creek, Cow Creek, the Spring, the Neosho, the Arkansas and the Mississippi: about 1,210 river miles.
Lakes on the way: Murray Lake and Ozark Lake.
600 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Arma; river miles along the main stem, rounded.
Arma has a hot-summer humid continental climate. Summer afternoons average 90° in July; winter nights fall to about 22° in January. A normal year brings about 6 inches of snow; with the rain, that comes to about 46 inches of water.
On November 14 Arma normally reaches 57° and falls to 36°. The record high is 80°, in 1964; the record low 5°, in 1959. The most rain on this date, 1.00 in, fell in 1958.
Normals 1991–2020 and records since 1957 at Girard, 8 miles west-southwest. NOAA, through RCC-ACIS.
