The Mendham 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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13° on Nov. 16, 1996, the coldest reading for this week of the year since 1892. Next is 14° in 1933.
Mendham’s center stands about 620 ft above sea level. Within three miles the land runs from 390 ft to 1,010 ft, a difference of 620 ft: hilly country. The highest named summit within 15 miles is Green Pond Mountain, about 1,300 ft, 14 miles north-northeast.
Under the town center the state geologic map shows Biotite-Quartz-Feldspar Gneiss (biotite-gneiss), from the Mesoproterozoic, 1 to 1.6 billion years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 20×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Granite. Age: Mesoproterozoic, 1.1 to 1.1 billion years old. About 7 mi of the line.
Siltstone, shale. Age: Early Jurassic to Late Jurassic, 145 to 202 million years old. About 5 mi of the line.
Age: Mesoproterozoic, 1 to 1.6 billion years old. About 4 mi of the line.
Biotite-gneiss. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 3 mi of the line.
Granite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 2 mi of the line.
Conglomerate-sandstone. Age: Early Jurassic to Late Jurassic, 145 to 202 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. 1 smaller unit 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 Mendham reaches New York Harbor and the Atlantic Ocean by way of the North Branch Raritan, North Branch Peapack Brook and the Raritan: about 50 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Mendham; river miles along the main stem, rounded.
Mendham has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 21° in January. About 49 inches of rain fall in a normal year.
On November 14 Mendham normally reaches 53° and falls to 33°. The record high is 80°, in 1931; the record low 19°, in 2019. The most rain on this date, 2.10 in, fell in 1937.
Normals 1991–2020 and records since 1892 at Boonton 1 SE, 13 miles northeast, 340 ft lower. NOAA, through RCC-ACIS.
