The Tiskilwa 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. 12, 2019, the coldest reading for this week of the year since 1893. Next is 0° in 1996.
Tiskilwa’s center stands about 530 ft above sea level. Within three miles the land runs from 490 ft to 820 ft, a difference of 330 ft: rolling country. The highest named summit within 15 miles is Gravel Hill, about 830 ft, 9 miles west.
Under the town center the state geologic map shows Carbondale Formation (shale, sandstone, coal), from the Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 43×. 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, sandstone, coal. Age: Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old. About 13 mi of the line.
Shale, limestone. Age: Late Pennsylvanian, 304 to 307 million years old. About 9 mi of the line.
Shale, sandstone. Age: Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 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 Tiskilwa reaches the Gulf of America by way of Big Bureau Creek, the Illinois and the Mississippi: about 1,410 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 Tiskilwa; river miles along the main stem, rounded.
Tiskilwa has a hot-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 13° in January. A normal year brings about 36 inches of snow; with the rain, that comes to about 37 inches of water.
On November 14 Tiskilwa normally reaches 48° and falls to 30°. The record high is 74°, in 1999; the record low 0°, in 1996. The most rain on this date, 1.83 in, fell in 1926.
Normals 1991–2020 and records since 1893 at Walnut, 19 miles north-northwest, 170 ft higher. NOAA, through RCC-ACIS.
