The Koshkonong 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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5.49 inches of rain fell in two days, the most for this week of the year since records began in 1904. The next wettest, 5.05 inches, fell in 2003.
Koshkonong’s center stands about 970 ft above sea level. Within three miles the land runs from 770 ft to 1,020 ft, a difference of 250 ft: rolling country.
Under the town center the state geologic map shows Smithville Dolomite, Powell Dolomite, Cotter Dolomite, Jefferson City Dolomite (dolostone), from the Early Ordovician, 471 to 487 million years old.
The section below crosses 2 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 33×. 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: Early Ordovician, 471 to 487 million years old. About 19 mi of the line.
Dolostone. Age: Early Ordovician, 471 to 487 million years old. About 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 Koshkonong reaches the Gulf of America by way of Bussell Branch, English Creek, the Spring, the Black River, the White River and the Mississippi: about 1,020 river miles.
620 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Koshkonong; river miles along the main stem, rounded.
Koshkonong has a humid subtropical climate. Summer afternoons average 90° in July; winter nights fall to about 23° in January. About 49 inches of rain fall in a normal year.
On November 14 Koshkonong normally reaches 60° and falls to 34°. The record high is 81°, in 1999; the record low 11°, in 1940. The most rain on this date, 1.60 in, fell in 1926.
Normals 1991–2020 and records since 1904 at Mammoth Spring, 9 miles southeast, 470 ft lower. NOAA, through RCC-ACIS.
