The Porterdale 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.
Sunny
Mostly sunny; warmer
Mostly sunny
Sunny
Sunny
Mostly sunny
Mostly sunny
Porterdale’s center stands about 680 ft above sea level. Within three miles the land runs from 600 ft to 830 ft, a difference of 230 ft: rolling country. The highest named summit within 15 miles is Alcovy Mountain, about 1,100 ft, 14 miles northeast.
Under the town center the state geologic map shows Biotitic Gneiss / Mica Schist/ Amphibolite (amphibolite, biotite-gneiss, mica-schist), from the Precambrian to Paleozoic.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 49×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Gneiss. Age: Precambrian to Paleozoic. About 14 mi of the line.
Amphibolite, biotite-gneiss, mica-schist. Age: Precambrian to Paleozoic. About 8 mi of the line.
Gneiss. Age: Precambrian to Paleozoic. About 1 mi of the line.
Schist. Age: Precambrian to Paleozoic. About 0.3 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 Porterdale reaches the Atlantic Ocean by way of the Yellow, the Ocmulgee and the Altamaha: about 390 river miles.
Lake on the way: Jackson Lake.
240 miles of the trip are on the Ocmulgee.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Porterdale; river miles along the main stem, rounded.
