The Jacobus 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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16° on Nov. 16, 1996, the coldest reading for this week of the year since 1988. Next is 17° in 2017.
Jacobus’s center stands about 670 ft above sea level. Within three miles the land runs from 430 ft to 840 ft, a difference of 410 ft: hilly country. The highest named summit within 15 miles is High Rock, about 1,210 ft, 13 miles west.
Under the town center the state geologic map shows Marburg Schist (phyllite, mica-schist), from the Paleozoic, 252 to 542 million years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 26×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Schist, phyllite. Age: Paleozoic, 252 to 542 million years old. About 9 mi of the line.
Arkose. Age: Triassic, 202 to 252 million years old. About 4 mi of the line.
Phyllite, mica-schist. Age: Paleozoic, 252 to 542 million years old. About 4 mi of the line.
Quartzite. Age: Cambrian, 487 to 542 million years old. About 3 mi of the line.
Limestone. Age: Cambrian, 487 to 542 million years old. About 2 mi of the line.
Quartzite, schist. Age: Cambrian, 487 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. 1 smaller unit 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 Jacobus reaches Chesapeake Bay and the Atlantic Ocean by way of East Branch Codorus Creek, South Branch Codorus Creek, Codorus Creek and the Susquehanna: about 75 river miles.
Lake on the way: Lake Aldred.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Jacobus; river miles along the main stem, rounded.
Jacobus has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 24° in January. A normal year brings about 34 inches of snow; with the rain, that comes to about 48 inches of water.
On November 14 Jacobus normally reaches 54° and falls to 36°. The record high is 73°, in 1993; the record low 22°, in 2019. The most rain on this date, 1.59 in, fell in 1995.
Normals 1991–2020 and records since 1988 at Millers 4 NE, 12 miles south-southwest, 190 ft higher. NOAA, through RCC-ACIS.
