The Tonica 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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1° on Nov. 17, 1959, the coldest reading for this week of the year since 1901. Next is 4° in 2019.
Tonica’s center stands about 660 ft above sea level. Within three miles the land runs from 620 ft to 700 ft, a difference of 80 ft: gently rolling country.
Under the town center the state geologic map shows Shelburn-Patoka Formations undivided (shale, limestone), from the Late Pennsylvanian, 304 to 307 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, limestone. Age: Late Pennsylvanian, 304 to 307 million years old. About 9 mi of the line.
Shale, sandstone, coal. Age: Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old. About 7 mi of the line.
Shale. Age: Late Pennsylvanian, 304 to 307 million years old. About 5 mi of the line.
Sandstone, limestone, dolostone. Age: Middle Ordovician to Late Ordovician, 454 to 468 million years old. About 2 mi of the line.
Shale, sandstone, limestone. Age: Late Pennsylvanian, 304 to 307 million years old. About 2 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 Tonica reaches the Gulf of America by way of Bailey Creek, the Vermilion, the Illinois and the Mississippi: about 1,430 river miles.
Lake on the way: Peoria Lake.
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 Tonica; river miles along the main stem, rounded.
Tonica has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 14° in January. A normal year brings about 28 inches of snow; with the rain, that comes to about 38 inches of water.
On November 14 Tonica normally reaches 49° and falls to 30°. The record high is 76°, in 1989; the record low 6°, in 1986. The most rain on this date, 2.04 in, fell in 1926.
Normals 1991–2020 and records since 1901 at Peru, 9 miles north-northwest. NOAA, through RCC-ACIS.
