The East St. Clair 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.
Partly cloudy
Mostly cloudy; warmer
Partly cloudy
Sunny
Sunny
Mostly sunny
Mostly sunny
11° on Nov. 14, 1986, the coldest reading for this week of the year since 1948. Next is 12° in 1959.
East St. Clair’s center stands about 1,100 ft above sea level. Within three miles the land runs from 1,090 ft to 1,590 ft, a difference of 500 ft: hilly country. The highest named summit within 15 miles is Blue Knob, about 3,140 ft, 11 miles north.
Under the town center the state geologic map shows Brallier and Harrell Formations, undivided (siltstone, shale), from the Late Devonian, 359 to 384 million years old.
The section below crosses 14 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 10×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Siltstone, shale. Age: Late Devonian, 359 to 384 million years old. About 5 mi of the line.
Black-shale. Age: Early Devonian to Middle Devonian, 384 to 422 million years old. About 4 mi of the line.
Siltstone. Age: Late Devonian, 359 to 384 million years old. About 3 mi of the line.
Sandstone, siltstone, shale. Age: Late Devonian, 359 to 384 million years old. About 3 mi of the line.
Sandstone, shale. Age: Ordovician, 445 to 487 million years old. About 2 mi of the line.
Shale, sandstone. Age: Silurian, 422 to 445 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. 8 smaller units 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 East St. Clair reaches Chesapeake Bay and the Atlantic Ocean by way of Dunning Creek, the Raystown Branch Juniata, the Juniata and the Susquehanna: about 280 river miles.
Lakes on the way: Lake Aldred and Raystown Lake.
90 miles of the trip are on the Juniata.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of East St. Clair; river miles along the main stem, rounded.
East St. Clair has a hot-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 21° in January. About 37 inches of rain fall in a normal year.
On November 14 East St. Clair normally reaches 51° and falls to 34°. The record high is 73°, in 1993; the record low 11°, in 1986. The most rain on this date, 2.25 in, fell in 1972.
Normals 1991–2020 and records since 1948 at Altoona Blair County Airport, 17 miles northeast, 360 ft higher. NOAA, through RCC-ACIS.
