The Shackle Island 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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15° on Nov. 13, 2019, the coldest reading for this week of the year since 1936. Next is 16° in 1969.
Shackle Island’s center stands about 530 ft above sea level. Within three miles the land runs from 490 ft to 860 ft, a difference of 370 ft: rolling country. The highest named summit within 15 miles is Pitt Hill, about 960 ft, 6 miles northeast.
Under the town center the state geologic map shows Ordovician [units] including Richmond Group (which includes Mannie Shale, Fernvale Limestone, Sequatchie Formation, and Arnheim Formation), the Maysville Group (which includes Leipers Formation), the Eden Group (which includes Inman Formation), and the Nashville Group (which includes Catheys Formation) (shale, limestone), from the Ordovician, 445 to 487 million years old.
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 35×. 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, limestone. Age: Ordovician, 445 to 487 million years old. About 9 mi of the line.
Chert. Age: Carboniferous, 324 to 359 million years old. About 8 mi of the line.
Fine-detrital, coarse-detrital. Age: Quaternary, less than 2.6 million years old. About 5 mi of the line.
Limestone. Age: Carboniferous, 324 to 359 million years old. About 2 mi of the line.
Limestone. Age: Silurian, 422 to 445 million years old. About 0.8 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 Shackle Island reaches the Gulf of America by way of Drakes Creek, the Cumberland, the Ohio and the Mississippi: about 1,260 river miles.
Lake on the way: Bards 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 Shackle Island; river miles along the main stem, rounded.
Shackle Island has a humid subtropical climate. Summer afternoons average 90° in July; winter nights fall to about 27° in January. About 48 inches of rain fall in a normal year, with about 1 inch of snow.
Normals 1991–2020 and records since 1936 at Old Hickory Dam, 6 miles south-southwest. NOAA, through RCC-ACIS.
