The Gwinn 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.
Mostly cloudy
Mostly sunny; warmer
Partly cloudy
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Chance of showers
66° on Nov. 13, 1999, the hottest reading for this week of the year since 1961. Next is 65° in 2001.
Gwinn’s center stands about 1,120 ft above sea level. Within three miles the land runs from 1,090 ft to 1,280 ft, a difference of 190 ft: gently rolling country. The highest named summit within 15 miles is Summit Mountain, about 1,820 ft, 14 miles northwest.
Under the town center the state geologic map shows Migmatitic gneiss and amphibolite (Late to Early Archean) (gneiss, amphibolite, migmatite), from the Paleoarchean to Neoarchean, 2.5 to 3.6 billion years old.
The section below crosses 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 39×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Gneiss, amphibolite, migmatite. Age: Paleoarchean to Neoarchean, 2.5 to 3.6 billion years old. About 8 mi of the line.
Sandstone. Age: Cambrian, 487 to 497 million years old. About 7 mi of the line.
Sandstone. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 4 mi of the line.
Gneiss, amphibolite. Age: Neoarchean, 2.5 to 2.8 billion years old. About 2 mi of the line.
Sandstone. Age: Cambrian, 487 to 497 million years old. About 2 mi of the line.
Slate. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 2 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 Gwinn reaches Lake Michigan by way of the East Branch Escanaba and the Escanaba: about 55 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 Gwinn; river miles along the main stem, rounded.
Gwinn has a warm-summer humid continental climate. Summer afternoons average 76° in July; winter nights fall to about 7° in January. A normal year brings about 197 inches of snow; with the rain, that comes to about 37 inches of water.
On November 14 Gwinn normally reaches 38° and falls to 25°. The record high is 59°, in 2001; the record low 5°, in 1995. The most rain on this date, 0.51 in, fell in 2020.
Normals 1991–2020 and records since 1961 from the Marquette County Area threaded record (Marquette Wfo, 18 miles north-northwest, 300 ft higher). NOAA, through RCC-ACIS.
