The St. Leonard 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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5.96 inches of rain fell in two days, the most for this week of the year since records began in 1893. The next wettest, 4.55 inches, fell in 2009.
St. Leonard’s center stands about 120 ft above sea level. Within three miles the land runs from 0 ft to 200 ft, a difference of 200 ft: gently rolling country. Open water lies within three miles.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Clay, sand. Age: Miocene, 5.3 to 23 million years old. About 6 mi of the line.
Gravel, sand. Age: Pleistocene, less than 2.6 million years old. About 6 mi of the line.
Sand, silt. Age: Miocene, 5.3 to 23 million years old. About 5 mi of the line.
Fine-detrital, coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 3 mi of the line.
Sand, clay. Age: Miocene, 5.3 to 23 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.
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 St. Leonard reaches Chesapeake Bay and the Atlantic Ocean by way of Perrin Branch, Saint Leonard Creek and the Patuxent: about 16 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of St. Leonard; river miles along the main stem, rounded.
St. Leonard has a cold desert climate. Summer afternoons average 88° in July; winter nights fall to about 30° in January. Barely 0.0 inches of rain fall in a normal year.
On November 14 St. Leonard normally reaches 59° and falls to 44°. The record high is 79°, in 1955; the record low 28°, in 1911. The most rain on this date, 0.79 in, fell in 1972.
Normals 1991–2020 and records since 1893 at Solomons, 10 miles south-southeast, 110 ft lower. NOAA, through RCC-ACIS.
