The Joanna 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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4.62 inches of rain fell in two days, the most for this week of the year since records began in 1901. The next wettest, 4.05 inches, fell in 1957.
Joanna’s center stands about 610 ft above sea level. Within three miles the land runs from 480 ft to 670 ft, a difference of 190 ft: gently rolling country.
Under the town center the state geologic map shows Biotite-quartz-feldspar gneiss of the Whitmire reentrant (biotite-gneiss), from the Neoproterozoic to Cambrian, 487 to 1,000 million years old.
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.
Biotite-gneiss. Age: Neoproterozoic to Cambrian, 487 to 1,000 million years old. About 24 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 Joanna reaches the Atlantic Ocean by way of Indian Creek, the Enoree, the Broad, the Congaree, the Santee and the South Santee: about 250 river miles.
Lake on the way: Lib Pines Lake.
70 miles of the trip are on the Santee.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Joanna; river miles along the main stem, rounded.
Joanna has a humid subtropical climate. Summer afternoons average 91° in July; winter nights fall to about 30° in January. About 47 inches of rain fall in a normal year, with about 1 inch of snow.
On November 14 Joanna normally reaches 64° and falls to 38°. The record high is 83°, in 1931; the record low 21°, in 1963. The most rain on this date, 1.24 in, fell in 1972.
Normals 1991–2020 and records since 1901 at Laurens, 13 miles west-northwest. NOAA, through RCC-ACIS.
