The Johnson Prairie 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.
Johnson Prairie’s center stands about 1,120 ft above sea level. Within three miles the land runs from 830 ft to 1,180 ft, a difference of 350 ft: rolling country.
Under the town center the state geologic map shows Keokuk and Reeds Spring Formations and St. Joe Group (chert, limestone), from the Carboniferous, 324 to 359 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 33×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Chert, limestone. Age: Carboniferous, 324 to 359 million years old. About 21 mi of the line.
Fine-detrital. Age: Holocene, less than 12,000 years old. About 3 mi of the line.
Shale, limestone, dolostone. Age: Early Ordovician to Carboniferous, 324 to 487 million years old. About 0.4 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 Johnson Prairie reaches the Gulf of America by way of Blackbird Creek, Fourteenmile Creek, the Neosho, the Arkansas and the Mississippi: about 1,040 river miles.
Lakes on the way: Murray Lake and Ozark Lake.
600 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Johnson Prairie; river miles along the main stem, rounded.