The Union 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° on Nov. 13, 2019, the coldest reading for this week of the year since 1893. Next is 9° in 1959.
Union’s center stands about 930 ft above sea level. Within three miles the land runs from 790 ft to 1,030 ft, a difference of 240 ft: rolling country.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 63×. 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, 425 to 445 million years old. About 15 mi of the line.
Shale, dolostone, limestone. Age: Ordovician, 445 to 487 million years old. About 7 mi of the line.
Dolostone, limestone, shale. Age: Silurian, 422 to 445 million years old. About 3 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 Union reaches the Gulf of America by way of the Stillwater, the Great Miami, the Ohio and the Mississippi: about 1,550 river miles.
970 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Union; river miles along the main stem, rounded.
Union has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 22° in January. A normal year brings about 25 inches of snow; with the rain, that comes to about 41 inches of water.
On November 14 Union normally reaches 53° and falls to 36°. The record high is 76°, in 1909; the record low 11°, in 1986. The most rain on this date, 1.44 in, fell in 1993.
Normals 1991–2020 and records since 1893 from the Dayton Area threaded record (Dayton International Airport, 5 miles east). NOAA, through RCC-ACIS.
