The Philadelphia 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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Philadelphia’s center stands about 460 ft above sea level. Within three miles the land runs from 390 ft to 540 ft, a difference of 150 ft: gently rolling country. The highest named summit within 15 miles is Circle Hill, about 710 ft, 10 miles southeast.
Under the town center the state geologic map shows Wilcox formation (sand, clay), from the Eocene, 34 to 56 million years old.
The section below crosses 2 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 60×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sand, clay. Age: Eocene, 34 to 56 million years old. About 19 mi of the line.
Claystone, clay. Age: Eocene, 34 to 56 million years old. About 5 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 Philadelphia reaches the Gulf of America by way of the Kentawka Canal and the Pearl: about 410 river miles.
Lake on the way: Cypress Lake.
310 miles of the trip are on the Pearl.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Philadelphia; river miles along the main stem, rounded.
