The Greenwich 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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78° on Nov. 15, 1993, the hottest reading for this week of the year since 1858. Next is 74° in 1902.
Greenwich’s center stands about 610 ft above sea level. Within three miles the land runs from 360 ft to 830 ft, a difference of 470 ft: hilly country. The highest named summit within 15 miles is Dans Pulpit, about 1,660 ft, 9 miles northwest.
Under the town center the state geologic map shows Hamburg sequence rocks (shale), from the Ordovician, 445 to 487 million years old.
The section below crosses 18 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 16×. 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. Age: Ordovician, 445 to 487 million years old. About 7 mi of the line.
Gneiss. Age: Precambrian. About 3 mi of the line.
Dolostone, limestone. Age: Cambrian, 487 to 542 million years old. About 3 mi of the line.
Shale, slate. Age: Ordovician, 445 to 487 million years old. About 2 mi of the line.
Shale. Age: Ordovician, 445 to 487 million years old. About 1 mi of the line.
Shale. Age: Silurian, 422 to 445 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. 12 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 Greenwich reaches Delaware Bay and the Atlantic Ocean by way of Maiden Creek, the Schuylkill and the Delaware: about 160 river miles.
85 miles of the trip are on the Schuylkill.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Greenwich; river miles along the main stem, rounded.
Greenwich has a hot-summer humid continental climate. Summer afternoons average 87° in July; winter nights fall to about 23° in January. About 45 inches of rain fall in a normal year.
On November 14 Greenwich normally reaches 54° and falls to 36°. The record high is 74°, in 1955; the record low 16°, in 1986. The most rain on this date, 1.37 in, fell in 1995.
Normals 1991–2020 and records since 1858 from the Reading Area threaded record (Reading 4 SW, 19 miles south-southwest, 290 ft lower). NOAA, through RCC-ACIS.
