The Harrisburg 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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13° on Nov. 15, 1940, the coldest reading for this week of the year since 1893. Next is 15° in 1916.
Harrisburg’s center stands about 280 ft above sea level. Within three miles the land runs from 240 ft to 440 ft, a difference of 200 ft: rolling country.
Under the town center the state geologic map shows Terrace deposits (coarse-detrital, fine-detrital), from the Pleistocene, less than 2.6 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 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.
Coarse-detrital, fine-detrital. Age: Pleistocene, less than 2.6 million years old. About 20 mi of the line.
Sand, clay. Age: Middle Eocene, 38 to 48 million years old. About 1 mi of the line.
Silt. Age: Pleistocene, less than 2.6 million years old. About 1.0 mi of the line.
Sand, gravel. Age: Pleistocene, less than 2.6 million years old. About 0.9 mi of the line.
Coarse-detrital, fine-detrital. Age: Holocene, less than 12,000 years old. About 0.7 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 Harrisburg reaches the Gulf of America by way of the L'Anguille, the Saint Francis and the Mississippi: about 810 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Harrisburg; river miles along the main stem, rounded.
Harrisburg has a humid subtropical climate. Summer afternoons average 91° in July; winter nights fall to about 30° in January. About 48 inches of rain fall in a normal year.
On November 14 Harrisburg normally reaches 60° and falls to 40°. The record high is 81°, in 1964; the record low 15°, in 1986. The most rain on this date, 3.73 in, fell in 1957.
Normals 1991–2020 and records since 1893 from the Jonesboro Area threaded record (Jonesboro Municipal Airport, 19 miles north-northeast). NOAA, through RCC-ACIS.
