The Mill Run 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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3.74 inches of rain fell in two days, the most for this week of the year since records began in 1967. The next wettest, 2.25 inches, fell in 1968.
Mill Run’s center stands about 1,280 ft above sea level. Within three miles the land runs from 1,060 ft to 2,480 ft, a difference of 1,420 ft: steep hill country. The highest named summit within 15 miles is Schaefer Head, about 2,970 ft, 14 miles south-southwest.
The section below crosses 16 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 11×. 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.
Shale, siltstone, sandstone. Age: Carboniferous, 324 to 359 million years old. About 5 mi of the line.
Sandstone, siltstone, shale. Age: Late Devonian, 359 to 384 million years old. About 2 mi of the line.
Limestone. Age: Silurian to Devonian, 359 to 445 million years old. About 2 mi of the line.
Sandstone. Age: Carboniferous, 324 to 359 million years old. About 2 mi of the line.
Sandstone. Age: Late Devonian, 359 to 384 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. 10 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 Mill Run reaches Chesapeake Bay and the Atlantic Ocean by way of Mill Run, Beaverdam Branch, the Frankstown Branch Juniata, the Juniata and the Susquehanna: about 230 river miles.
Lake on the way: Lake Aldred.
100 miles of the trip are on the Juniata.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Mill Run; river miles along the main stem, rounded.
Mill Run has a warm-summer humid continental climate. Summer afternoons average 81° in July; winter nights fall to about 19° in January. A normal year brings about 38 inches of snow; with the rain, that comes to about 45 inches of water.
On November 14 Mill Run normally reaches 49° and falls to 33°. The record high is 70°, in 2011; the record low 11°, in 1986. The most rain on this date, 1.18 in, fell in 1972.
Normals 1991–2020 and records since 1967 at Altoona 3 W, here. NOAA, through RCC-ACIS.
