The Randallstown 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.
Randallstown’s center stands about 590 ft above sea level. Within three miles the land runs from 360 ft to 670 ft, a difference of 310 ft: rolling country.
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 8 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 28×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Gabbro. Age: Proterozoic to Paleozoic, 252 to 2,500 million years old. About 6 mi of the line.
Biotite-schist. Age: Proterozoic, 542 to 2,500 million years old. About 6 mi of the line.
Muscovite-schist. Age: Proterozoic, 542 to 2,500 million years old. About 5 mi of the line.
Serpentinite. Age: Proterozoic to Paleozoic, 252 to 2,500 million years old. About 3 mi of the line.
Sand. Age: Cretaceous, 66 to 145 million years old. About 2 mi of the line.
Gneiss. Age: Precambrian. About 0.7 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 2 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 Randallstown reaches Chesapeake Bay and the Atlantic Ocean by way of Scotts Level Branch, the Gwynns Falls and the Patapsco: about 30 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Randallstown; river miles along the main stem, rounded.
Randallstown 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 Randallstown 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, 12 miles east-southeast, 570 ft lower). NOAA, through RCC-ACIS.
