The Sylvania 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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10° on Nov. 15, 1969, the coldest reading for this week of the year since 1893. Next is 12° in 1940.
Sylvania’s center stands about 1,370 ft above sea level. Within three miles the land runs from 1,240 ft to 1,430 ft, a difference of 190 ft: gently rolling country. The highest named summit within 15 miles is Little Mountain, about 1,860 ft, 11 miles east.
Under the town center the state geologic map shows Pottsville Formation (sandstone, conglomerate), from the Carboniferous, 299 to 324 million years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 16×. 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, conglomerate. Age: Carboniferous, 299 to 324 million years old. About 19 mi of the line.
Limestone. Age: Carboniferous, 324 to 359 million years old. About 1 mi of the line.
Dolostone, limestone. Age: Cambrian to Ordovician, 445 to 542 million years old. About 1 mi of the line.
Shale, limestone. Age: Ordovician, 445 to 487 million years old. About 0.7 mi of the line.
Sandstone, shale. Age: Silurian, 422 to 445 million years old. About 0.6 mi of the line.
Limestone, dolostone, shale. Age: Carboniferous, 324 to 359 million years old. About 0.3 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 1 smaller unit along the line are not listed.
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 Sylvania reaches the Gulf of America by way of Caney Creek, Town Creek, the Tennessee, the Ohio and the Mississippi: about 1,420 river miles.
Lakes on the way: Guntersville Lake, White Lake (historical) and Pickwick Lake.
970 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Sylvania; river miles along the main stem, rounded.
Sylvania has a humid subtropical climate. Summer afternoons average 86° in July; winter nights fall to about 30° in January. A normal year brings about 5 inches of snow; with the rain, that comes to about 58 inches of water.
On November 14 Sylvania normally reaches 61° and falls to 38°. The record high is 80°, in 1931; the record low 18°, in 2013. The most rain on this date, 2.53 in, fell in 1957.
Normals 1991–2020 and records since 1893 at Valley Head, 11 miles east, 250 ft lower. NOAA, through RCC-ACIS.
