The Dewey 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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0° on Nov. 12, 2019, the coldest reading for this week of the year since 1888. Next is 3° in 1959.
Dewey’s center stands about 730 ft above sea level. Within three miles the land runs from 700 ft to 740 ft, a difference of 40 ft: nearly flat ground.
Under the town center the state geologic map shows New Albany Shale, Blocher Shale, Sylamore Sandstone, Selmier Shale, Sweetland Creek Shale, Grassy Creek Shale, Saverton Shale, and Louisiana Limestone, from the Middle Devonian to Late Devonian, 359 to 388 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.
Shale. Age: Middle Devonian to Late Devonian, 359 to 388 million years old. About 10 mi of the line.
Dolostone, limestone. Age: Silurian, 422 to 445 million years old. About 7 mi of the line.
Shale, sandstone. Age: Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 million years old. About 4 mi of the line.
Limestone. Age: Middle Devonian, 384 to 394 million years old. About 3 mi of the line.
Siltstone. Age: Early Mississippian to Middle Mississippian, 331 to 359 million years old. About 0.3 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 Dewey reaches the Gulf of America by way of Wildcat Slough, the Sangamon, the Illinois and the Mississippi: about 1,480 river miles.
1,190 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Dewey; river miles along the main stem, rounded.
Dewey has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 18° in January. A normal year brings about 21 inches of snow; with the rain, that comes to about 41 inches of water.
On November 14 Dewey normally reaches 51° and falls to 33°. The record high is 75°, in 1971; the record low 10°, in 1986. The most rain on this date, 1.33 in, fell in 1957.
Normals 1991–2020 and records since 1888 at Champaign 3 S, 16 miles south. NOAA, through RCC-ACIS.
