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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−2° on Nov. 12, 2019, the coldest reading for this week of the year since 1921. Next is 1° in 1986.
Delaware’s center stands about 1,050 ft above sea level. Within three miles the land runs from 950 ft to 1,100 ft, a difference of 150 ft: gently rolling country.
Under the town center the state geologic map shows Hopkinton, Blanding, Tete Des Morts, Mosalem formations (dolostone), from the Late Ordovician to Silurian, 434 to 447 million years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 63×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Dolostone. Age: Late Ordovician to Silurian, 434 to 447 million years old. About 15 mi of the line.
Dolostone. Age: Silurian, 431 to 440 million years old. About 6 mi of the line.
Shale, dolostone. Age: Late Ordovician, 447 to 454 million years old. About 3 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 Penn Creek, Plum Creek, the Maquoketa and the Mississippi: about 1,640 river miles.
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 warm-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 8° in January. A normal year brings about 35 inches of snow; with the rain, that comes to about 39 inches of water.
On November 14 Delaware normally reaches 46° and falls to 26°. The record high is 77°, in 1999; the record low 1°, in 1986. The most rain on this date, 0.49 in, fell in 1994.
Normals 1991–2020 and records since 1921 at Manchester #2, 6 miles west, 130 ft lower. NOAA, through RCC-ACIS.
