The Troy 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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75° on Nov. 11, 2020, the hottest reading for this week of the year since 1894. Next is 75° in 2022.
Troy’s center stands about 750 ft above sea level. Within three miles the land runs from 650 ft to 900 ft, a difference of 250 ft: rolling country. The highest named summit within 15 miles is Grampian Hills, about 1,270 ft, 15 miles north.
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 40×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale. Age: Carboniferous, 324 to 359 million years old. About 16 mi of the line.
Black-shale. Age: Late Devonian, 359 to 384 million years old. About 6 mi of the line.
Shale. Age: Late Devonian, 359 to 384 million years old. About 1 mi of the line.
Black-shale. Age: Devonian to Carboniferous, 324 to 422 million years old. About 1 mi of the line.
Sandstone. Age: Late Devonian, 359 to 384 million years old. About 0.7 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 Troy reaches Lake St. Clair by way of the Sturgis Drain, Big Beaver Creek, Red Run and the Clinton: about 30 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 Troy; river miles along the main stem, rounded.
Troy has a hot-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 17° in January. A normal year brings about 36 inches of snow; with the rain, that comes to about 34 inches of water.
On November 14 Troy normally reaches 48° and falls to 32°. The record high is 69°, in 1909; the record low 12°, in 1986. The most rain on this date, 2.25 in, fell in 1997.
Normals 1991–2020 and records since 1894 at Pontiac Wwtp, 6 miles west-northwest, 140 ft higher. NOAA, through RCC-ACIS.
