The Coggon 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.
Sunny
Mostly sunny; warmer
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Partly cloudy
Mostly sunny
Chance of showers
−2° on Nov. 12, 2019, the coldest reading for this week of the year since 1921. Next is 1° in 1986.
Coggon’s center stands about 940 ft above sea level. Within three miles the land runs from 850 ft to 1,020 ft, a difference of 170 ft: gently rolling country.
Under the town center the state geologic map shows Scotch Grove Formation (dolostone), from the Silurian, 431 to 440 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.
Dolostone. Age: Silurian, 431 to 440 million years old. About 10 mi of the line.
Dolostone, limestone. Age: Middle Devonian, 384 to 394 million years old. About 8 mi of the line.
Limestone, dolostone. Age: Middle Devonian to Late Devonian, 374 to 388 million years old. About 4 mi of the line.
Dolostone, mudstone. Age: Silurian, 425 to 434 million years old. About 1 mi of the line.
Limestone. Age: Silurian, 431 to 440 million years old. About 0.7 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 Coggon reaches the Gulf of America by way of Buffalo Creek, the Wapsipinicon and the Mississippi: about 1,600 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Coggon; river miles along the main stem, rounded.
Coggon has a warm-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 8° in January. A normal year brings about 35 inches of snow; with the rain, that comes to about 39 inches of water.
On November 14 Coggon normally reaches 46° and falls to 26°. The record high is 77°, in 1999; the record low 1°, in 1986. The most rain on this date, 0.49 in, fell in 1994.
Normals 1991–2020 and records since 1921 at Manchester #2, 14 miles north-northeast. NOAA, through RCC-ACIS.
