The Upper Uwchlan 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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78° on Nov. 15, 1993, the hottest reading for this week of the year since 1893. Next is 77° in 1973.
Upper Uwchlan’s center stands about 410 ft above sea level. Within three miles the land runs from 330 ft to 760 ft, a difference of 430 ft: hilly country. The highest named summit within 15 miles is Welsh Mountain, about 1,080 ft, 13 miles west.
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 22×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Gneiss. Age: Precambrian. About 5 mi of the line.
Gneiss. Age: Precambrian. About 3 mi of the line.
Muscovite-gneiss. Age: Precambrian. About 2 mi of the line.
Gneiss. Age: Precambrian. About 2 mi of the line.
Dolostone. Age: Cambrian, 487 to 542 million years old. About 2 mi of the line.
Basalt. Age: Jurassic, 145 to 202 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. 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 Upper Uwchlan reaches Delaware Bay and the Atlantic Ocean by way of Marsh Creek, East Branch Brandywine Creek, Brandywine Creek, the Christina and the Delaware: about 75 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Upper Uwchlan; river miles along the main stem, rounded.
Upper Uwchlan has a hot-summer humid continental climate. Summer afternoons average 88° in July; winter nights fall to about 23° in January. About 45 inches of rain fall in a normal year.
On November 14 Upper Uwchlan normally reaches 56° and falls to 35°. The record high is 75°, in 1955; the record low 19°, in 1950. The most rain on this date, 2.56 in, fell in 1972.
Normals 1991–2020 and records since 1893 at Phoenixville 1 E, 12 miles east-northeast, 270 ft lower. NOAA, through RCC-ACIS.
