The Onamia 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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Showers likely
Onamia’s center stands about 1,260 ft above sea level. Within three miles the land runs from 1,240 ft to 1,310 ft, a difference of 70 ft: gently rolling country.
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 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.
Tonalite, diorite. Age: Paleoproterozoic, 1.6 to 1.8 billion years old. About 22 mi of the line.
Granodiorite, granite. Age: Paleoproterozoic, 1.6 to 1.8 billion years old. About 2 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 Onamia reaches the Gulf of America by way of the Rum and the Mississippi: about 1,990 river miles.
Lake on the way: Lake Pepin.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Onamia; river miles along the main stem, rounded.
