The Llewellyn 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
Partly cloudy
Partly cloudy
Mostly sunny
Sunny
Mostly sunny
Mostly sunny
Llewellyn’s center stands about 760 ft above sea level. Within three miles the land runs from 710 ft to 1,470 ft, a difference of 760 ft: hilly country. The highest named summit within 15 miles is Locust Mountain, about 1,880 ft, 13 miles north-northeast.
Under the town center the state geologic map shows Llewellyn Formation (sandstone), from the Carboniferous, 299 to 324 million years old.
The section below crosses 15 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 15×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone. Age: Carboniferous, 299 to 324 million years old. About 5 mi of the line.
Shale, siltstone, sandstone. Age: Carboniferous, 324 to 359 million years old. About 4 mi of the line.
Sandstone. Age: Carboniferous, 299 to 324 million years old. About 4 mi of the line.
Black-shale. Age: Early Devonian to Middle Devonian, 384 to 422 million years old. About 2 mi of the line.
Sandstone, siltstone. Age: Late Devonian, 359 to 384 million years old. About 2 mi of the line.
Siltstone, mudstone. Age: Late Devonian, 359 to 384 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. 9 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 Llewellyn reaches Delaware Bay and the Atlantic Ocean by way of West Creek, the West West Branch Schuylkill, the West Branch Schuylkill, the Schuylkill and the Delaware: about 190 river miles.
120 miles of the trip are on the Schuylkill.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Llewellyn; river miles along the main stem, rounded.
