The Landmark 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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17° on Nov. 13, 2019, the coldest reading for this week of the year since 1875. Next is 20° in 1940.
Landmark’s center stands about 410 ft above sea level. Within three miles the land runs from 250 ft to 450 ft, a difference of 200 ft: gently rolling country. The highest named summit within 15 miles is Alexander Mountain, about 600 ft, 7 miles west.
Under the town center the state geologic map shows Wilcox Group (sand, fine-detrital), from the Early Eocene, 48 to 56 million years old.
The section below crosses 8 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 48×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sand, fine-detrital. Age: Early Eocene, 48 to 56 million years old. About 6 mi of the line.
Coarse-detrital, fine-detrital. Age: Pleistocene, less than 2.6 million years old. About 6 mi of the line.
Coarse-detrital, fine-detrital. Age: Holocene, less than 12,000 years old. About 5 mi of the line.
Novaculite. Age: Late Devonian to Carboniferous, 324 to 384 million years old. About 3 mi of the line.
Clay, marl. Age: Paleocene, 56 to 66 million years old. About 2 mi of the line.
Black-shale, sandstone, siltstone. Age: Carboniferous, 324 to 359 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. 2 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 Landmark reaches the Gulf of America by way of Landmark Branch, Lorance Creek, Pennington Bayou, the Arkansas and the Mississippi: about 730 river miles.
600 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Landmark; river miles along the main stem, rounded.
Landmark has a humid subtropical climate. Summer afternoons average 92° in July; winter nights fall to about 31° in January. About 50 inches of rain fall in a normal year, with about 4 inches of snow.
On November 14 Landmark normally reaches 62° and falls to 40°. The record high is 83°, in 1999; the record low 22°, in 1986. The most rain on this date, 3.57 in, fell in 1958.
Normals 1991–2020 and records since 1875 from the Little Rock Area threaded record (Little Rock Airport Adams Field, 9 miles north-northeast, 160 ft lower). NOAA, through RCC-ACIS.
