The McLean 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.
McLean’s center stands about 1,830 ft above sea level. Within three miles the land runs from 1,720 ft to 1,850 ft, a difference of 130 ft: gently rolling country.
Under the town center the state geologic map shows Ogallala Group or Formation (siltstone-mudstone, conglomerate-sandstone), from the Miocene, 5.3 to 23 million years old.
The section below crosses 2 rock units mapped at the surface.
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.
Siltstone-mudstone, conglomerate-sandstone. Age: Miocene, 5.3 to 23 million years old. About 21 mi of the line.
Shale. Age: Late Cretaceous, 66 to 100 million years old. About 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 McLean reaches the Gulf of America by way of Yankton Slough, the North Fork Elkhorn, the Elkhorn, the Platte, the Missouri and the Mississippi: about 1,960 river miles.
1,170 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of McLean; river miles along the main stem, rounded.