The Lake Johanna 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
Lake Johanna’s center stands about 1,310 ft above sea level. Within three miles the land runs from 1,270 ft to 1,380 ft, a difference of 110 ft: gently rolling country.
The section below crosses 5 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.
Orthogneiss. Age: Paleoarchean to Mesoarchean, 2.8 to 3.6 billion years old. About 12 mi of the line.
Orthogneiss, migmatite. Age: Paleoarchean to Mesoarchean, 2.8 to 3.6 billion years old. About 6 mi of the line.
Gabbro, pyroxenite, diorite. Age: Paleoproterozoic, 1.6 to 1.8 billion years old. About 6 mi of the line.
Volcanic, sedimentary, hypabyssal. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 0.7 mi of the line.
Granodiorite, granite. Age: Paleoproterozoic, 1.6 to 1.8 billion 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 Lake Johanna reaches the Gulf of America by way of Mud Creek, the East Branch Chippewa, the Chippewa, the Minnesota and the Mississippi: about 2,180 river miles.
Lake on the way: Lake Pepin.
1,750 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Lake Johanna; river miles along the main stem, rounded.
