The Chadwick 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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−2° on Nov. 12, 2019, the coldest reading for this week of the year since 1895. Next is −1° in 1898.
Chadwick’s center stands about 800 ft above sea level. Within three miles the land runs from 710 ft to 900 ft, a difference of 190 ft: gently rolling country.
Under the town center the state geologic map shows Maquoketa Formation or Group (shale, limestone), from the Late Ordovician, 445 to 454 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 51×. 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 Ordovician, 445 to 454 million years old. About 10 mi of the line.
Dolostone, limestone. Age: Late Ordovician, 447 to 459 million years old. About 10 mi of the line.
Dolostone, limestone. Age: Silurian, 422 to 445 million years old. About 2 mi of the line.
Dolostone, limestone. Age: Late Ordovician, 454 to 459 million years old. About 2 mi of the line.
Sandstone, limestone, dolostone. Age: Middle Ordovician to Late Ordovician, 454 to 468 million years old. About 0.5 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 Chadwick reaches the Gulf of America by way of Rock Creek, the Rock River and the Mississippi: about 1,540 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Chadwick; river miles along the main stem, rounded.
Chadwick has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 11° in January. A normal year brings about 33 inches of snow; with the rain, that comes to about 40 inches of water.
On November 14 Chadwick normally reaches 49° and falls to 28°. The record high is 73°, in 1999; the record low 3°, in 1986. The most rain on this date, 1.30 in, fell in 1899.
Normals 1991–2020 and records since 1895 at Mount Carroll, 8 miles northwest. NOAA, through RCC-ACIS.
