The Chelsea 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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73° on Nov. 11, 2020, the hottest reading for this week of the year since 1880. Next is 71° in 1909.
Chelsea’s center stands about 940 ft above sea level. Within three miles the land runs from 880 ft to 1,030 ft, a difference of 150 ft: gently rolling country. The highest named summit within 15 miles is Sugarloaf Hill, about 1,130 ft, 5 miles west-northwest.
Under the town center the state geologic map shows Marshall Sandstone, from the Carboniferous, 324 to 359 million years old.
The section below crosses 2 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.
Sandstone. Age: Carboniferous, 324 to 359 million years old. About 12 mi of the line.
Shale. Age: Carboniferous, 324 to 359 million years old. About 12 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 Chelsea reaches Lake Erie by way of North Fork Mill Creek, Mill Creek and the Huron: about 75 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 Chelsea; river miles along the main stem, rounded.
Chelsea has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 16° in January. A normal year brings about 61 inches of snow; with the rain, that comes to about 38 inches of water.
On November 14 Chelsea normally reaches 49° and falls to 31°. The record high is 71°, in 1909; the record low 11°, in 2018. The most rain on this date, 1.31 in, fell in 1957.
Normals 1991–2020 and records since 1880 at Ann Arbor U Of Mich, 18 miles east, 130 ft lower. NOAA, through RCC-ACIS.
