The East Rocky Hill 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
Partly cloudy
Mostly sunny
Sunny
Mostly sunny
Mostly sunny
79° on Nov. 16, 1993, the hottest reading for this week of the year since 1893. Next is 76° in 2020.
East Rocky Hill’s center stands about 150 ft above sea level. Within three miles the land runs from 60 ft to 340 ft, a difference of 280 ft: rolling country. The highest named summit within 15 miles is Sourland Mountain, about 640 ft, 7 miles west-northwest.
Under the town center the state geologic map shows Passaic Formation (siltstone), from the Late Triassic to Early Jurassic, 175 to 237 million years old.
The section below crosses 8 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 35×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Siltstone, shale. Age: Early Jurassic to Late Jurassic, 145 to 202 million years old. About 6 mi of the line.
Sand. Age: Late Cretaceous, 84 to 87 million years old. About 6 mi of the line.
Plutonic. Age: Jurassic, 145 to 202 million years old. About 4 mi of the line.
Siltstone. Age: Late Triassic to Early Jurassic, 175 to 237 million years old. About 4 mi of the line.
Silt, sand. Age: Late Cretaceous, 94 to 100 million years old. About 2 mi of the line.
Siltstone-mudstone, sandstone-mudstone. Age: Late Triassic, 202 to 237 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. 2 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 East Rocky Hill reaches New York Harbor and the Atlantic Ocean by way of the Millstone and the Raritan: about 35 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of East Rocky Hill; river miles along the main stem, rounded.
East Rocky Hill has a hot-summer humid continental climate. Summer afternoons average 87° in July; winter nights fall to about 23° in January. A normal year brings about 29 inches of snow; with the rain, that comes to about 50 inches of water.
On November 14 East Rocky Hill normally reaches 56° and falls to 36°. The record high is 72°, in 1955; the record low 15°, in 1986. The most rain on this date, 0.81 in, fell in 1940.
Normals 1991–2020 and records since 1893 from the New Brunswick Area threaded record (New Brunswick 3 SE, 11 miles east-northeast). NOAA, through RCC-ACIS.
