The Tredyffrin 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 sunny; warmer
Partly cloudy
Sunny
Sunny
Mostly sunny
Mostly sunny
78° on Nov. 15, 1993, the hottest reading for this week of the year since 1893. Next is 77° in 1973.
Tredyffrin’s center stands about 230 ft above sea level. Within three miles the land runs from 100 ft to 630 ft, a difference of 530 ft: hilly country. The highest named summit within 15 miles is Diamond Rock Hill, about 700 ft, 3 miles west-northwest.
The section below crosses 9 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 28×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Limestone. Age: Cambrian, 487 to 542 million years old. About 6 mi of the line.
Schist, phyllite. Age: Paleozoic, 252 to 542 million years old. About 5 mi of the line.
Muscovite-gneiss. Age: Precambrian. About 5 mi of the line.
Mica-schist. Age: Paleozoic, 252 to 542 million years old. About 2 mi of the line.
Gneiss. Age: Precambrian. About 2 mi of the line.
Limestone. Age: Cambrian to Ordovician, 445 to 542 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. 3 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 Tredyffrin reaches Delaware Bay and the Atlantic Ocean by way of Valley Creek, the Schuylkill and the Delaware: about 95 river miles.
60 miles of the trip are on the Delaware.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Tredyffrin; river miles along the main stem, rounded.
Tredyffrin 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 Tredyffrin 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, 4 miles north-northwest. NOAA, through RCC-ACIS.
