The Lake 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.
Lake’s center stands about 1,080 ft above sea level. Within three miles the land runs from 1,070 ft to 1,130 ft, a difference of 60 ft: gently rolling country.
Under the town center the state geologic map shows Foliated to gneissic tonalite, granodiorite, and diorite (tonalite, granodiorite, diorite), from the Neoarchean, 2.5 to 2.8 billion years old.
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.
Tonalite, granodiorite, diorite. Age: Neoarchean, 2.5 to 2.8 billion years old. About 9 mi of the line.
Felsic-volcanic. Age: Neoarchean, 2.5 to 2.8 billion years old. About 4 mi of the line.
Gabbro, peridotite, pyroxenite. Age: Neoarchean, 2.5 to 2.8 billion years old. About 3 mi of the line.
Metabasalt, greenstone. Age: Neoarchean, 2.5 to 2.8 billion years old. About 2 mi of the line.
Plutonic. Age: Archean. About 1 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.