The Posen 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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72° on Nov. 17, 1953, the hottest reading for this week of the year since 1916. Next is 69° in 1931.
Posen’s center stands about 790 ft above sea level. Within three miles the land runs from 720 ft to 840 ft, a difference of 120 ft: gently rolling country. The highest named summit within 15 miles is Manning Hill, about 960 ft, 14 miles south.
Under the town center the state geologic map shows Traverse Group (limestone), from the Middle Devonian, 384 to 394 million years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 62×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Limestone. Age: Middle Devonian, 384 to 394 million years old. About 18 mi of the line.
Limestone. Age: Middle Devonian, 384 to 394 million years old. About 4 mi of the line.
Black-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.
A raindrop that lands in Posen reaches Lake Huron by way of Erskine Creek, the North Branch Thunder Bay and the Thunder Bay: about 25 river miles. 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 Posen; river miles along the main stem, rounded.
Posen has a warm-summer humid continental climate. Summer afternoons average 81° in July; winter nights fall to about 11° in February. A normal year brings about 78 inches of snow; with the rain, that comes to about 30 inches of water.
On November 14 Posen normally reaches 45° and falls to 29°. The record high is 66°, in 1994; the record low 3°, in 1940. The most rain on this date, 0.61 in, fell in 1957.
Normals 1991–2020 and records since 1916 from the Alpena Area threaded record (Alpena County Regional Airport, 15 miles south-southeast, 110 ft lower). NOAA, through RCC-ACIS.
