The Griswold 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.
83° on Nov. 14, 1999, the hottest reading for this week of the year since 1919. Next is 78° in 1949.
Griswold’s center stands about 1,110 ft above sea level. Within three miles the land runs from 1,070 ft to 1,290 ft, a difference of 220 ft: rolling country.
The section below crosses 4 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.
Sandstone, shale. Age: Early Cretaceous to Late Cretaceous, 94 to 113 million years old. About 19 mi of the line.
Shale, mudstone. Age: Late Pennsylvanian, 299 to 307 million years old. About 3 mi of the line.
Limestone, shale. Age: Late Pennsylvanian, 299 to 307 million years old. About 2 mi of the line.
Limestone, shale. Age: Late Pennsylvanian, 299 to 307 million years old. About 0.4 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 Griswold reaches the Gulf of America by way of Baughmans Creek, the East Nishnabotna, the Nishnabotna, the Missouri and the Mississippi: about 1,770 river miles.
1,170 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Griswold; river miles along the main stem, rounded.
Griswold has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 12° in January. A normal year brings about 28 inches of snow; with the rain, that comes to about 36 inches of water.
On November 14 Griswold normally reaches 49° and falls to 28°. The record high is 83°, in 1999; the record low −6°, in 1940. The most rain on this date, 1.21 in, fell in 2024.
Normals 1991–2020 and records since 1919 at Oakland, 14 miles west-northwest, 150 ft higher. NOAA, through RCC-ACIS.