The Louisiana 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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6° on Nov. 12, 2019, the coldest reading for this week of the year since 1948. Next is 16° in 1995.
Louisiana’s center stands about 500 ft above sea level. Within three miles the land runs from 440 ft to 820 ft, a difference of 380 ft: rolling country. The highest named summit within 15 miles is Buffalo Knob, about 1,030 ft, 11 miles south.
The section below crosses 12 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 34×. 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 Ordovician to Late Ordovician, 445 to 471 million years old. About 8 mi of the line.
Shale, limestone. Age: Late Ordovician, 445 to 454 million years old. About 5 mi of the line.
Limestone, siltstone. Age: Carboniferous, 324 to 359 million years old. About 4 mi of the line.
Limestone. Age: Early Mississippian to Middle Mississippian, 331 to 359 million years old. About 2 mi of the line.
Limestone, dolostone. Age: Late Ordovician, 447 to 454 million years old. About 2 mi of the line.
Shale. Age: Middle Devonian to Late Devonian, 359 to 388 million years old. About 0.9 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 6 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 Louisiana reaches the Gulf of America by way of Noix Creek and the Mississippi: about 1,250 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Louisiana; river miles along the main stem, rounded.
Louisiana has a hot-summer humid continental climate. Summer afternoons average 87° in July; winter nights fall to about 20° in January. A normal year brings about 12 inches of snow; with the rain, that comes to about 38 inches of water.
On November 14 Louisiana normally reaches 54° and falls to 35°. The record high is 79°, in 1999; the record low 10°, in 2019. The most rain on this date, 0.73 in, fell in 1993.
Normals 1991–2020 and records since 1948 at Clarksville L&D 24, 9 miles southeast. NOAA, through RCC-ACIS.
