The Delaware 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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77° on Nov. 11, 2020, the hottest reading for this week of the year since 1917. Next is 75° in 1949.
Delaware’s center stands about 880 ft above sea level. Within three miles the land runs from 860 ft to 990 ft, a difference of 130 ft: gently rolling country.
Under the town center the state geologic map shows Delaware Limestone, from the Devonian, 359 to 422 million years old.
The section below crosses 6 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.
Shale, black-shale. Age: Devonian, 359 to 422 million years old. About 10 mi of the line.
Dolostone. Age: Silurian, 422 to 445 million years old. About 5 mi of the line.
Limestone. Age: Devonian, 359 to 422 million years old. About 3 mi of the line.
Limestone. Age: Devonian, 359 to 422 million years old. About 3 mi of the line.
Sandstone, shale. Age: Devonian, 359 to 422 million years old. About 2 mi of the line.
Shale. Age: Devonian, 359 to 422 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 Delaware reaches the Gulf of America by way of the Olentangy, the Scioto, the Ohio and the Mississippi: about 1,750 river miles.
970 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Delaware; river miles along the main stem, rounded.
Delaware has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 21° in January. A normal year brings about 24 inches of snow; with the rain, that comes to about 40 inches of water.
On November 14 Delaware normally reaches 52° and falls to 34°. The record high is 73°, in 1971; the record low 12°, in 1920. The most rain on this date, 1.32 in, fell in 1972.
Normals 1991–2020 and records since 1917 at Marysville, 13 miles southwest. NOAA, through RCC-ACIS.
