The Glencoe 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.
Glencoe’s center stands about 2,770 ft above sea level. Within three miles the land runs from 970 ft to 2,900 ft, a difference of 1,930 ft: steep hill country. The highest named summit within 15 miles is Blue Mountain, about 6,020 ft, 12 miles east.
Under the town center the state geologic map shows Paleozoic marine rocks, undivided, unit 4 (Western Sierra Nevada) (argillite, quartzite, phyllite), from the Ordovician to Triassic, 202 to 487 million years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 5×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Granodiorite. Age: Permian to Tertiary, 2.6 to 260 million years old. About 13 mi of the line.
Argillite, quartzite, phyllite. Age: Ordovician to Triassic, 202 to 487 million years old. About 8 mi of the line.
Mafic-volcanic. Age: Jurassic, 145 to 202 million years old. About 3 mi of the line.
Slate, graywacke. Age: Triassic to Late Jurassic, 145 to 252 million 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.
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 Glencoe reaches San Francisco Bay and the Pacific Ocean by way of the Mokelumne, the South Mokelumne, the San Joaquin and New York Slough: about 120 river miles.
Lake on the way: Camanche Reservoir.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Glencoe; river miles along the main stem, rounded.