The Fort Polk South 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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20° on Nov. 13, 2019, the coldest reading for this week of the year since 1903. Next is 21° in 1950.
Fort Polk South’s center stands about 320 ft above sea level. Within three miles the land runs from 240 ft to 390 ft, a difference of 150 ft: gently rolling country.
Under the town center the state geologic map shows Blounts Creek Member (siltstone-mudstone), from the Late Miocene to Early Pliocene, 3.6 to 12 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 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.
Clay, silt, sand. Age: Pleistocene, less than 2.6 million years old. About 9 mi of the line.
Siltstone-mudstone. Age: Late Miocene to Early Pliocene, 3.6 to 12 million years old. About 8 mi of the line.
Clay, silt. Age: Miocene, 5.3 to 23 million years old. About 6 mi of the line.
Clay. Age: Holocene, less than 12,000 years old. About 2 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 Fort Polk South reaches the Gulf of America by way of Bundick Creek, Whisky Chitto Creek and the Calcasieu: about 160 river miles.
Lake on the way: Mud Lake.
65 miles of the trip are on the Calcasieu.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Fort Polk South; river miles along the main stem, rounded.
Fort Polk South has a humid subtropical climate. Summer afternoons average 93° in July; winter nights fall to about 37° in January. About 59 inches of rain fall in a normal year.
On November 14 Fort Polk South normally reaches 69° and falls to 45°. The record high is 89°, in 1921; the record low 26°, in 2013. The most rain on this date, 3.55 in, fell in 1998.
Normals 1991–2020 and records since 1903 at Leesville, 6 miles north-northwest, 290 ft lower. NOAA, through RCC-ACIS.
