The Lerna 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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Mostly sunny; warmer
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3° on Nov. 17, 1959, the coldest reading for this week of the year since 1896. Next is 4° in 2019.
Lerna’s center stands about 760 ft above sea level. Within three miles the land runs from 670 ft to 770 ft, a difference of 100 ft: gently rolling country.
Under the town center the state geologic map shows Mattoon Formation (shale), from the Late Pennsylvanian, 304 to 307 million years old.
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.
Shale. Age: Late Pennsylvanian, 304 to 307 million years old. About 24 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 Lerna reaches the Gulf of America by way of Indian Creek, the Embarras, Big Bayou, the Wabash River Old Channel, the Old Channel Wabash, the Ohio and the Mississippi: about 1,330 river miles.
970 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Lerna; river miles along the main stem, rounded.
Lerna has a hot-summer humid continental climate. Summer afternoons average 88° in July; winter nights fall to about 21° in January. A normal year brings about 19 inches of snow; with the rain, that comes to about 44 inches of water.
On November 14 Lerna normally reaches 55° and falls to 35°. The record high is 78°, in 1955; the record low 10°, in 1986. The most rain on this date, 2.49 in, fell in 1993.
Normals 1991–2020 and records since 1896 at Charleston, 8 miles east-northeast. NOAA, through RCC-ACIS.
