The Columbia 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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82° on Nov. 15, 1993, the hottest reading for this week of the year since 1950. Next is 80° in 1973.
Columbia’s center stands about 400 ft above sea level. Within three miles the land runs from 290 ft to 540 ft, a difference of 250 ft: rolling country. The highest named summit within 15 miles is Chestnut Hill, about 610 ft, 4 miles north-northeast.
Under the town center the state geologic map shows Wissahickon Formation; Lower Pelitic Schist (biotite-schist), from the Proterozoic, 542 to 2,500 million years old.
The section below crosses 9 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 31×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Biotite-schist. Age: Proterozoic, 542 to 2,500 million years old. About 8 mi of the line.
Gneiss. Age: Precambrian. About 4 mi of the line.
Sand. Age: Cretaceous, 66 to 145 million years old. About 3 mi of the line.
Gabbro. Age: Proterozoic to Paleozoic, 252 to 2,500 million years old. About 2 mi of the line.
Fine-detrital, coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 2 mi of the line.
Quartz-monzonite. Age: Middle Ordovician to Late Devonian, 370 to 470 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. 3 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 Columbia reaches Chesapeake Bay and the Atlantic Ocean by way of the Little Patuxent and the Patuxent: about 90 river miles.
65 miles of the trip are on the Patuxent.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Columbia; river miles along the main stem, rounded.
Columbia has a humid subtropical climate. Summer afternoons average 90° in July; winter nights fall to about 30° in January. About 44 inches of rain fall in a normal year.
On November 14 Columbia normally reaches 58° and falls to 43°. The record high is 78°, in 1989; the record low 21°, in 1986. The most rain on this date, 2.46 in, fell in 1972.
Normals 1991–2020 and records since 1950 from the Baltimore Downtown Area threaded record (Maryland Science Center, 13 miles east-northeast, 380 ft lower). NOAA, through RCC-ACIS.
