The Seneca 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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Mostly sunny; warmer
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75° on Nov. 14, 1999, the hottest reading for this week of the year since 1956. Next is 70° in 1990.
Seneca’s center stands about 1,250 ft above sea level. Within three miles the land runs from 830 ft to 1,250 ft, a difference of 420 ft: hilly country.
Under the town center the state geologic map shows Ancell Group (sandstone), from the Ordovician, 445 to 487 million years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 30×. 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 8 mi of the line.
Sandstone. Age: Cambrian, 487 to 542 million years old. About 5 mi of the line.
Sandstone. Age: Ordovician, 445 to 487 million years old. About 5 mi of the line.
Sandstone. Age: Middle Cambrian to Cambrian, 487 to 521 million years old. About 2 mi of the line.
Sandstone, dolostone. Age: Cambrian, 487 to 497 million years old. About 2 mi of the line.
Sandstone, shale. Age: Middle Cambrian, 497 to 521 million years old. About 1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 1 smaller unit along the line are not listed.
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 Seneca reaches the Gulf of America by way of Halls Branch, the Kickapoo, the Wisconsin and the Mississippi: about 1,660 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Seneca; river miles along the main stem, rounded.
Seneca has a hot-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 7° in January. A normal year brings about 38 inches of snow; with the rain, that comes to about 38 inches of water.
On November 14 Seneca normally reaches 46° and falls to 27°. The record high is 75°, in 1999; the record low 6°, in 1996. The most rain on this date, 0.57 in, fell in 1994.
Normals 1991–2020 and records since 1956 at Gays Mills, 6 miles east-northeast, 560 ft lower. NOAA, through RCC-ACIS.
