The Chatham 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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70° on Nov. 11, 2016, the hottest reading for this week of the year since 1987. Next is 64° in 1990.
Chatham’s center stands about 890 ft above sea level. Within three miles the land runs from 800 ft to 1,040 ft, a difference of 240 ft: rolling country.
Under the town center the state geologic map shows Prairie du Chien Group (dolostone), from the Early Ordovician, 471 to 487 million 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 42×. 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: Late Ordovician, 445 to 459 million years old. About 11 mi of the line.
Sandstone. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 4 mi of the line.
Sandstone. Age: Cambrian, 487 to 497 million years old. About 3 mi of the line.
Sandstone. Age: Cambrian, 487 to 497 million years old. About 3 mi of the line.
Dolostone. Age: Early Ordovician, 471 to 487 million years old. About 3 mi of the line.
Limestone, dolostone. Age: Late Ordovician, 445 to 459 million years old. About 0.1 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 Chatham reaches Lake Superior by way of Bohemian Creek, Slapneck Creek and the Au Train: about 20 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 Chatham; river miles along the main stem, rounded.
Chatham has a warm-summer humid continental climate. Summer afternoons average 78° in July; winter nights fall to about 7° in February. A normal year brings about 164 inches of snow; with the rain, that comes to about 35 inches of water.
On November 14 Chatham normally reaches 41° and falls to 26°. The record high is 60°, in 1999; the record low 11°, in 2018. The most rain on this date, 0.63 in, fell in 2000.
Normals 1991–2020 and records since 1987 at Chatham Experiment Farm 2, here. NOAA, through RCC-ACIS.
