The Derma 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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5.00 inches of rain fell in two days, the most for this week of the year since records began in 1915. The next wettest, 3.80 inches, fell in 1961.
Derma’s center stands about 290 ft above sea level. Within three miles the land runs from 240 ft to 390 ft, a difference of 150 ft: gently rolling country. The highest named summit within 15 miles is Johnny Main Mountain, about 560 ft, 12 miles north.
Under the town center the state geologic map shows Naheola formation (sand, clay), from the Paleocene, 56 to 66 million years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 59×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sand, clay. Age: Paleocene, 56 to 66 million years old. About 13 mi of the line.
Sand, clay. Age: Eocene, 34 to 56 million years old. About 10 mi of the line.
Clay. Age: Paleocene, 56 to 66 million years old. About 0.6 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 Derma reaches the Gulf of America by way of the Yalobusha, the Yazoo and the Mississippi: about 710 river miles.
450 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Derma; river miles along the main stem, rounded.
Derma has a humid subtropical climate. Summer afternoons average 91° in July; winter nights fall to about 32° in January. About 58 inches of rain fall in a normal year.
On November 14 Derma normally reaches 65° and falls to 40°. The record high is 87°, in 1955; the record low 20°, in 2019. The most rain on this date, 4.60 in, fell in 1957.
Normals 1991–2020 and records since 1915 at Calhoun City, here. NOAA, through RCC-ACIS.
