The Malvern 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.
Malvern’s center stands about 580 ft above sea level. Within three miles the land runs from 190 ft to 600 ft, a difference of 410 ft: hilly country.
Under the town center the state geologic map shows Octoraro Formation (schist, phyllite), from the Paleozoic, 252 to 542 million years old.
The section below crosses 12 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 35×. 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 6 mi of the line.
Gneiss. Age: Precambrian. About 3 mi of the line.
Arkose. Age: Triassic, 202 to 252 million years old. About 3 mi of the line.
Mudstone. Age: Triassic, 202 to 252 million years old. About 2 mi of the line.
Mica-schist. Age: Paleozoic, 252 to 542 million years old. About 2 mi of the line.
Argillite. Age: Triassic, 202 to 252 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. 6 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 Malvern reaches Delaware Bay and the Atlantic Ocean by way of Crum Creek and the Delaware: about 75 river miles.
50 miles of the trip are on the Delaware.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Malvern; river miles along the main stem, rounded.
Malvern 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 Malvern 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, 6 miles north-northeast, 440 ft lower. NOAA, through RCC-ACIS.
