The Cassoday 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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84° on Nov. 17, 2016, the hottest reading for this week of the year since 1893. Next is 82° in 1949.
Cassoday’s center stands about 1,480 ft above sea level. Within three miles the land runs from 1,430 ft to 1,530 ft, a difference of 100 ft: gently rolling country. The highest named summit within 15 miles is Texaco Hill, about 1,630 ft, 15 miles east-northeast.
Under the town center the state geologic map shows Chase Group (shale, limestone), from the Permian, 252 to 299 million years old.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 59×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale, limestone. Age: Permian, 252 to 299 million years old. About 18 mi of the line.
Limestone, shale. Age: Permian, 252 to 299 million years old. About 3 mi of the line.
Shale. Age: Carboniferous, 299 to 324 million years old. About 3 mi of the line.
Sand, silt, clay. Age: Pleistocene to Holocene, less than 2.6 million years old. About 0.5 mi of the line.
Sand, silt, clay. Age: Pleistocene, less than 2.6 million years old. About 0.4 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 Cassoday reaches the Gulf of America by way of the Walnut, the Arkansas and the Mississippi: about 1,390 river miles.
Lakes on the way: El Dorado Lake, 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 Cassoday; river miles along the main stem, rounded.
Cassoday has a hot-summer humid continental climate. Summer afternoons average 91° in July; winter nights fall to about 20° in January. About 39 inches of rain fall in a normal year, with about 4 inches of snow.
On November 14 Cassoday normally reaches 58° and falls to 34°. The record high is 79°, in 2025; the record low 7°, in 1940. The most rain on this date, 1.78 in, fell in 1985.
Normals 1991–2020 and records since 1893 at El Dorado, 19 miles southwest, 190 ft lower. NOAA, through RCC-ACIS.
