The Cobb Island 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.
Partly cloudy
Partly cloudy; warmer
Mostly sunny
Partly cloudy
Partly cloudy
Mostly sunny
Mostly sunny
3.96 inches of rain fell in two days, the most for this week of the year since records began in 1927. The next wettest, 3.65 inches, fell in 2009.
Cobb Island’s center stands about 15 ft above sea level. Within three miles the land runs from 0 ft to 70 ft, a difference of 70 ft: gently rolling country. Open water lies within three miles. The highest named summit within 15 miles is Smith Mount Hill, about 240 ft, 11 miles south-southwest.
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.
Sand. Age: Tertiary, 2.6 to 66 million years old. About 4 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.
Gravel, sand. Age: Pleistocene, less than 2.6 million years old. About 1 mi of the line.
Sand. Age: Tertiary, 2.6 to 66 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.
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 Cobb Island reaches Chesapeake Bay and the Atlantic Ocean by way of the Wicomico and the Potomac: about 40 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Cobb Island; river miles along the main stem, rounded.
Cobb Island has a humid subtropical climate. Summer afternoons average 85° in July; winter nights fall to about 25° in January. A normal year brings about 15 inches of snow; with the rain, that comes to about 48 inches of water.
On November 14 Cobb Island normally reaches 58° and falls to 36°. The record high is 79°, in 1985; the record low 17°, in 1986. The most rain on this date, 1.11 in, fell in 1997.
Normals 1991–2020 and records since 1927 at Mechanicsville 5 NE, 17 miles north-northeast. NOAA, through RCC-ACIS.
