The Louisa 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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5.98 inches of rain fell in two days, the most for this week of the year since records began in 1916. The next wettest, 4.01 inches, fell in 1926.
Louisa’s center stands about 460 ft above sea level. Within three miles the land runs from 330 ft to 560 ft, a difference of 230 ft: rolling country. The highest named summit within 15 miles is Merry Mountain, about 1,170 ft, 14 miles northwest.
Under the town center the state geologic map shows Ellisville Biotite Granodiorite, from the Ordovician to Silurian, 422 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 58×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Metavolcanic. Age: Cambrian, 487 to 542 million years old. About 9 mi of the line.
Granodiorite. Age: Ordovician to Silurian, 422 to 487 million years old. About 9 mi of the line.
Metavolcanic. Age: Cambrian, 487 to 542 million years old. About 2 mi of the line.
Melange. Age: Neoproterozoic to Ordovician, 445 to 1,000 million years old. About 1 mi of the line.
Melange. Age: Neoproterozoic to Ordovician, 445 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.
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 Louisa reaches Chesapeake Bay and the Atlantic Ocean by way of Tanyard Branch, Beaver Creek, the South Anna, the Pamunkey and the York: about 200 river miles.
90 miles of the trip are on the Pamunkey.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Louisa; river miles along the main stem, rounded.
Louisa has a humid subtropical climate. Summer afternoons average 87° in July; winter nights fall to about 25° in January. A normal year brings about 16 inches of snow; with the rain, that comes to about 44 inches of water.
On November 14 Louisa normally reaches 58° and falls to 34°. The record high is 80°, in 1985; the record low 8°, in 1920. The most rain on this date, 1.67 in, fell in 1972.
Normals 1991–2020 and records since 1916 at Louisa, here. NOAA, through RCC-ACIS.
