The Silverdale 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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75° on Nov. 11, 2020, the hottest reading for this week of the year since 1948. Next is 72° in 2005.
Silverdale’s center stands about 440 ft above sea level. Within three miles the land runs from 310 ft to 680 ft, a difference of 370 ft: rolling country. The highest named summit within 15 miles is Flint Hill, about 1,030 ft, 13 miles north-northwest.
Under the town center the state geologic map shows Brunswick Formation (mudstone), from the Triassic, 202 to 252 million years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 38×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Mudstone. Age: Triassic, 202 to 252 million years old. About 11 mi of the line.
Argillite. Age: Triassic, 202 to 252 million years old. About 7 mi of the line.
Arkose. Age: Triassic, 202 to 252 million years old. About 4 mi of the line.
Basalt. Age: Jurassic, 145 to 202 million years old. About 3 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.
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 Silverdale reaches Delaware Bay and the Atlantic Ocean by way of Pleasant Spring Creek, East Branch Perkiomen Creek, Perkiomen Creek, the Schuylkill and the Delaware: about 120 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 Silverdale; river miles along the main stem, rounded.
Silverdale has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 19° in January. A normal year brings about 22 inches of snow; with the rain, that comes to about 52 inches of water.
On November 14 Silverdale normally reaches 54° and falls to 32°. The record high is 66°, in 2010; the record low 18°, in 1996. The most rain on this date, 0.55 in, fell in 2008.
Normals 1991–2020 and records since 1948 at Sellersville, 2 miles west-northwest, 140 ft lower. NOAA, through RCC-ACIS.
