The Bertha 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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Bertha’s center stands about 1,400 ft above sea level. Within three miles the land runs from 1,370 ft to 1,470 ft, a difference of 100 ft: gently rolling country.
Under the town center the state geologic map shows Granitic intrusion of unknown age, from the Archean to Paleoproterozoic.
The section below crosses 8 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.
Schist. Age: Neoarchean, 2.5 to 2.8 billion years old. About 9 mi of the line.
Granitic. Age: Archean to Paleoproterozoic. About 8 mi of the line.
Felsic-volcanic. Age: Neoarchean, 2.5 to 2.8 billion years old. About 5 mi of the line.
Metabasalt, greenstone. Age: Neoarchean, 2.5 to 2.8 billion years old. About 0.6 mi of the line.
Conglomerate, sandstone, mudstone. Age: Late Cretaceous, 72 to 100 million years old. About 0.5 mi of the line.
Schist, paragneiss. Age: Neoarchean, 2.5 to 2.8 billion years old. About 0.5 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 2 smaller units along the line are not listed.
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 Bertha reaches the Gulf of America by way of the Little Partridge, the Partridge, the Crow Wing and the Mississippi: about 2,030 river miles.
Lake on the way: Lake Pepin.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Bertha; river miles along the main stem, rounded.
