The Tilghmanton 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.
Tilghmanton’s center stands about 500 ft above sea level. Within three miles the land runs from 350 ft to 540 ft, a difference of 190 ft: gently rolling country. The highest named summit within 15 miles is Black Rock, about 1,870 ft, 8 miles east-northeast.
Under the town center the state geologic map shows Conococheague Limestone, from the Cambrian to Early Ordovician, 471 to 497 million years old.
The section below crosses 14 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.
Limestone. Age: Cambrian to Early Ordovician, 471 to 497 million years old. About 7 mi of the line.
Shale. Age: Ordovician, 445 to 487 million years old. About 3 mi of the line.
Limestone, shale. 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.
Dolostone. Age: Cambrian, 487 to 542 million years old. About 2 mi of the line.
Quartzite. Age: Proterozoic to Cambrian, 487 to 2,500 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. 8 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 Tilghmanton reaches Chesapeake Bay and the Atlantic Ocean by way of Marsh Run and the Potomac: about 200 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Tilghmanton; river miles along the main stem, rounded.
Tilghmanton 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 Tilghmanton 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, 12 miles north, 190 ft higher). NOAA, through RCC-ACIS.
