The Grenloch 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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81° on Nov. 15, 1993, the hottest reading for this week of the year since 1871. Next is 76° in 1955.
Grenloch’s center stands about 70 ft above sea level. Within three miles the land runs from 30 ft to 190 ft, a difference of 160 ft: gently rolling country.
Under the town center the state geologic map shows Lower Member of the Kirkwood Formation (clay, sand), from the Early Miocene, 16 to 23 million years old.
The section below crosses 9 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: Middle Miocene, 12 to 14 million years old. About 10 mi of the line.
Clay, sand. Age: Early Miocene, 16 to 23 million years old. About 4 mi of the line.
Sand. Age: Late Cretaceous, 84 to 87 million years old. About 2 mi of the line.
Sand, clay. Age: Late Cretaceous, 72 to 84 million years old. About 2 mi of the line.
Sand. Age: Late Cretaceous, 72 to 84 million years old. About 1 mi of the line.
Sand. Age: Late Cretaceous, 72 to 84 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. 3 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 Grenloch reaches Delaware Bay and the Atlantic Ocean by way of South Branch Big Timber Creek, Big Timber Creek and the Delaware: about 75 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Grenloch; river miles along the main stem, rounded.
Grenloch has a humid subtropical climate. Summer afternoons average 88° in July; winter nights fall to about 26° in January. A normal year brings about 23 inches of snow; with the rain, that comes to about 44 inches of water.
On November 14 Grenloch normally reaches 56° and falls to 39°. The record high is 76°, in 1955; the record low 19°, in 1986. The most rain on this date, 2.64 in, fell in 1972.
Normals 1991–2020 and records since 1871 from the Philadelphia Area threaded record (Philadelphia International Airport, 11 miles northwest). NOAA, through RCC-ACIS.
