The Boonsboro 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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1° on Nov. 16, 1908, the coldest reading for this week of the year since 1899. Next is 9° in 1933.
Boonsboro’s center stands about 550 ft above sea level. Within three miles the land runs from 400 ft to 1,440 ft, a difference of 1,040 ft: steep hill country. The highest named summit within 15 miles is High Rock, about 1,930 ft, 15 miles north-northeast.
Under the town center the state geologic map shows Tomstown Dolomite (dolostone), from the Cambrian, 487 to 542 million years old.
The section below crosses 12 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 13×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Metabasalt. Age: Proterozoic to Mesoproterozoic, 1 to 2.5 billion years old. About 5 mi of the line.
Dolostone. Age: Cambrian, 487 to 542 million years old. About 4 mi of the line.
Limestone. Age: Cambrian, 487 to 542 million years old. About 4 mi of the line.
Quartzite. Age: Proterozoic to Cambrian, 487 to 2,500 million years old. About 3 mi of the line.
Limestone. Age: Cambrian to Early Ordovician, 471 to 497 million years old. About 3 mi of the line.
Metarhyolite. Age: Proterozoic, 542 to 2,500 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. 6 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 Boonsboro reaches Chesapeake Bay and the Atlantic Ocean by way of Antietam Creek and the Potomac: about 190 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Boonsboro; river miles along the main stem, rounded.
Boonsboro has a humid subtropical climate. Summer afternoons average 87° in July; winter nights fall to about 25° in January. About 36 inches of rain fall in a normal year.
On November 14 Boonsboro normally reaches 55° and falls to 38°. The record high is 75°, in 1989; the record low 10°, in 1920. The most rain on this date, 1.91 in, fell in 1995.
Normals 1991–2020 and records since 1899 from the Hagerstown Area threaded record (Hagerstown Regional Airport, 14 miles north-northwest, 140 ft higher). NOAA, through RCC-ACIS.
