The Gretna 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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Mostly sunny; warmer
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4.36 inches of rain fell in two days, the most for this week of the year since records began in 1922. The next wettest, 2.62 inches, fell in 1925.
Gretna’s center stands about 850 ft above sea level. Within three miles the land runs from 690 ft to 1,080 ft, a difference of 390 ft: rolling country. The highest named summit within 15 miles is Smith Mountain, about 2,060 ft, 12 miles west-northwest.
Under the town center the state geologic map shows Fork Mountain Formation (mica-schist), from the Neoproterozoic to Cambrian, 487 to 1,000 million years old.
The section below crosses 11 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 14×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Mica-schist. Age: Neoproterozoic to Cambrian, 487 to 1,000 million years old. About 12 mi of the line.
Shale, sandstone, siltstone. Age: Triassic, 202 to 252 million years old. About 3 mi of the line.
Granite. Age: Cambrian, 487 to 542 million years old. About 2 mi of the line.
Phyllite, schist. Age: Cambrian, 487 to 542 million years old. About 1 mi of the line.
Amphibolite. Age: Neoproterozoic to Cambrian, 487 to 1,000 million years old. About 1 mi of the line.
Metagraywacke. Age: Neoproterozoic to Cambrian, 487 to 1,000 million years old. About 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. 5 smaller units 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 Gretna reaches Albemarle Sound and the Atlantic Ocean by way of Georges Creek, the Banister, the Dan and the Roanoke: about 270 river miles.
Lake on the way: Roanoke Rapids Lake.
130 miles of the trip are on the Roanoke.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Gretna; river miles along the main stem, rounded.
Gretna has a humid subtropical climate. Summer afternoons average 86° in July; winter nights fall to about 24° in January. A normal year brings about 6 inches of snow; with the rain, that comes to about 48 inches of water.
On November 14 Gretna normally reaches 60° and falls to 32°. The record high is 80°, in 1955; the record low 13°, in 1986. The most rain on this date, 2.44 in, fell in 1972.
Normals 1991–2020 and records since 1922 at Chatham, 9 miles south-southwest, 200 ft lower. NOAA, through RCC-ACIS.
