The Bonneauville 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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14° on Nov. 14, 1986, the coldest reading for this week of the year since 1972. Next is 15° in 1996.
Bonneauville’s center stands about 580 ft above sea level. Within three miles the land runs from 480 ft to 640 ft, a difference of 160 ft: gently rolling country. The highest named summit within 15 miles is Big Hill, about 1,630 ft, 14 miles west-northwest.
Under the town center the state geologic map shows Gettysburg Formation (siltstone-mudstone, shale), from the Triassic, 202 to 252 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 29×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Siltstone-mudstone, shale. Age: Triassic, 202 to 252 million years old. About 9 mi of the line.
Arkose. Age: Triassic, 202 to 252 million years old. About 5 mi of the line.
Basalt. Age: Jurassic, 145 to 202 million years old. About 3 mi of the line.
Age: Precambrian. About 3 mi of the line.
Quartzite, schist. Age: Cambrian, 487 to 542 million years old. About 1 mi of the line.
Dolostone. Age: Cambrian, 487 to 542 million years old. About 1 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 Bonneauville reaches Chesapeake Bay and the Atlantic Ocean by way of Chicken Run, White Run, Rock Creek, the Monocacy and the Potomac: about 230 river miles.
160 miles of the trip are on the Potomac.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Bonneauville; river miles along the main stem, rounded.
Bonneauville has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 22° in January. A normal year brings about 27 inches of snow; with the rain, that comes to about 45 inches of water.
On November 14 Bonneauville normally reaches 54° and falls to 35°. The record high is 66°, in 1973; the record low 14°, in 1986. The most rain on this date, 1.28 in, fell in 1972.
Normals 1991–2020 and records since 1972 at Biglerville, 11 miles northwest, 140 ft higher. NOAA, through RCC-ACIS.
