The Eighty Four 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.
Mostly cloudy
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13° on Nov. 13, 2019, the coldest reading for this week of the year since 1935. Next is 17° in 2017.
Eighty Four’s center stands about 1,070 ft above sea level. Within three miles the land runs from 990 ft to 1,360 ft, a difference of 370 ft: rolling country. The highest named summit within 15 miles is Mount Wheeler, about 1,490 ft, 7 miles west-southwest.
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 28×. 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: Permian, 252 to 299 million years old. About 8 mi of the line.
Limestone, shale, sandstone. Age: Carboniferous, 299 to 324 million years old. About 7 mi of the line.
Sandstone, shale. Age: Permian, 252 to 299 million years old. About 5 mi of the line.
Sandstone, shale. Age: Carboniferous to Permian, 252 to 324 million years old. About 3 mi of the line.
Shale, clastic. Age: Carboniferous, 299 to 324 million years old. About 2 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 Eighty Four reaches the Gulf of America by way of Little Chartiers Creek, Chartiers Creek, the Ohio and the Mississippi: about 1,980 river miles.
970 miles of the trip are on the Ohio.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Eighty Four; river miles along the main stem, rounded.
Eighty Four has a hot-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 22° in January. About 41 inches of rain fall in a normal year.
On November 14 Eighty Four normally reaches 52° and falls to 36°. The record high is 70°, in 2011; the record low 18°, in 1942. The most rain on this date, 0.54 in, fell in 2011.
Normals 1991–2020 and records since 1935 at Pittsburgh Allegheny County Airport, 16 miles northeast, 170 ft higher. NOAA, through RCC-ACIS.
