The Harrison 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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4° on Nov. 16, 1933, the coldest reading for this week of the year since 1896. Next is 10° in 1908.
Harrison’s center stands about 580 ft above sea level. Within three miles the land runs from 570 ft to 620 ft, a difference of 50 ft: nearly flat ground.
Under the town center the state geologic map shows Antrim Shale (black-shale), from the Late Devonian, 359 to 384 million years old.
The section below crosses 5 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.
Black-shale. Age: Late Devonian, 359 to 384 million years old. About 8 mi of the line.
Black-shale. Age: Devonian to Carboniferous, 324 to 422 million years old. About 2 mi of the line.
Shale. Age: Carboniferous, 324 to 359 million years old. About 2 mi of the line.
Sandstone. Age: Late Devonian, 359 to 384 million years old. About 1 mi of the line.
Shale. Age: Late Devonian, 359 to 384 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.
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.
Rain that falls on Harrison runs only a short way, about 2 miles, to Lake St. Clair. From there it moves on through the Great Lakes, over Niagara Falls and down the St. Lawrence to the Atlantic.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Harrison; river miles along the main stem, rounded.
Harrison has a hot-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 18° in January. A normal year brings about 32 inches of snow; with the rain, that comes to about 35 inches of water.
On November 14 Harrison normally reaches 48° and falls to 33°. The record high is 70°, in 1909; the record low 11°, in 1933. The most rain on this date, 0.94 in, fell in 1957.
Normals 1991–2020 and records since 1896 at Mt. Clemens Ang Base, here. NOAA, through RCC-ACIS.
