The Allegheny 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
Chance of showers; warmer
Mostly cloudy
Partly cloudy
Sunny
Mostly sunny
Mostly sunny
78° on Nov. 11, 2020, the hottest reading for this week of the year since 1927. Next is 70° in 2005.
Allegheny’s center stands about 1,190 ft above sea level. Within three miles the land runs from 770 ft to 1,310 ft, a difference of 540 ft: hilly country.
Under the town center the state geologic map shows Casselman Formation (shale, clastic), 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 23×. 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. Age: Carboniferous, 299 to 324 million years old. About 15 mi of the line.
Shale, clastic. Age: Carboniferous, 299 to 324 million years old. About 8 mi of the line.
Sandstone. 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 Allegheny reaches the Gulf of America by way of the Kiskiminetas, the Allegheny, 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 Allegheny; river miles along the main stem, rounded.
Allegheny has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 21° in January. About 42 inches of rain fall in a normal year.
Normals 1991–2020 and records since 1927 at Natrona Lock 4, 4 miles west, 430 ft lower. NOAA, through RCC-ACIS.
