The Jefferson 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 1858. Next is 74° in 1902.
Jefferson’s center stands about 540 ft above sea level. Within three miles the land runs from 320 ft to 680 ft, a difference of 360 ft: rolling country. The highest named summit within 15 miles is Eagle Peak, about 1,320 ft, 7 miles south.
Under the town center the state geologic map shows Hamburg sequence rocks (shale), from the Ordovician, 445 to 487 million years old.
The section below crosses 11 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 14×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale. Age: Ordovician, 445 to 487 million years old. About 10 mi of the line.
Shale. Age: Ordovician, 445 to 487 million years old. About 6 mi of the line.
Sandstone, conglomerate. Age: Silurian, 422 to 445 million years old. About 2 mi of the line.
Dolostone. Age: Ordovician, 445 to 487 million years old. About 2 mi of the line.
Siltstone, sandstone. Age: Late Devonian, 359 to 384 million years old. About 1 mi of the line.
Black-shale. Age: Early Devonian to Middle Devonian, 384 to 422 million years old. About 0.8 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 5 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 Jefferson reaches Delaware Bay and the Atlantic Ocean by way of Little Northkill Creek, Tulpehocken Creek, the Schuylkill and the Delaware: about 150 river miles.
75 miles of the trip are on the Schuylkill.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Jefferson; river miles along the main stem, rounded.
Jefferson has a hot-summer humid continental climate. Summer afternoons average 87° in July; winter nights fall to about 23° in January. About 45 inches of rain fall in a normal year.
On November 14 Jefferson normally reaches 54° and falls to 36°. The record high is 74°, in 1955; the record low 16°, in 1986. The most rain on this date, 1.37 in, fell in 1995.
Normals 1991–2020 and records since 1858 from the Reading Area threaded record (Reading 4 SW, 13 miles southeast, 220 ft lower). NOAA, through RCC-ACIS.
