The Sewickley 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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9° on Nov. 16, 1933, the coldest reading for this week of the year since 1871. Next is 10° in 1986.
Sewickley’s center stands about 770 ft above sea level. Within three miles the land runs from 680 ft to 1,220 ft, a difference of 540 ft: hilly country. The highest named summit within 15 miles is Big Knob, about 1,400 ft, 13 miles north.
Under the town center the state geologic map shows Glenshaw Formation (shale), from the Carboniferous, 299 to 324 million years old.
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 31×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale, clastic. Age: Carboniferous, 299 to 324 million years old. About 20 mi of the line.
Limestone, shale, sandstone. Age: Carboniferous, 299 to 324 million years old. About 3 mi of the line.
Shale. Age: Carboniferous, 299 to 324 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.
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 Sewickley reaches the Gulf of America by way of the Ohio and the Mississippi: about 1,930 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 Sewickley; river miles along the main stem, rounded.
Sewickley has a hot-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 21° in January. A normal year brings about 44 inches of snow; with the rain, that comes to about 40 inches of water.
On November 14 Sewickley normally reaches 52° and falls to 35°. The record high is 76°, in 1879; the record low 10°, in 1986. The most rain on this date, 1.07 in, fell in 1993.
Normals 1991–2020 and records since 1871 from the Pittsburgh Area threaded record (Pittsburgh International Airport, 4 miles south-southwest, 350 ft higher). NOAA, through RCC-ACIS.
