The Gibson City 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.
Gibson City’s center stands about 740 ft above sea level. Within three miles the land runs from 730 ft to 810 ft, a difference of 80 ft: gently rolling country.
Under the town center the state geologic map shows Silurian System undivided (dolostone, limestone), from the Silurian, 422 to 445 million years old.
The section below crosses 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Dolostone, limestone. Age: Silurian, 422 to 445 million years old. About 13 mi of the line.
Shale, sandstone, limestone. Age: Late Pennsylvanian, 304 to 307 million years old. About 6 mi of the line.
Shale, limestone. Age: Late Pennsylvanian, 304 to 307 million years old. About 2 mi of the line.
Shale, sandstone. Age: Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 million years old. About 2 mi of the line.
Shale, sandstone, coal. Age: Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old. About 0.7 mi of the line.
Limestone. Age: Middle Devonian, 384 to 394 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 Gibson City reaches the Gulf of America by way of Drummer Creek, the Sangamon, the Illinois and the Mississippi: about 1,500 river miles.
1,190 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Gibson City; river miles along the main stem, rounded.