The Lockwood 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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Lockwood’s center stands about 3,180 ft above sea level. Within three miles the land runs from 2,160 ft to 3,600 ft, a difference of 1,440 ft: steep hill country. The highest named summit within 15 miles is Armstrong Hill, about 5,740 ft, 12 miles east-northeast.
Under the town center the state geologic map shows Tertiary pyroclastic and volcanic mudflow deposits, unit 9 (Cascade Range) (andesite), from the Late Oligocene to Pleistocene, 2 to 24 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.
Argillite, quartzite, phyllite. Age: Ordovician to Triassic, 202 to 487 million years old. About 12 mi of the line.
Andesite. Age: Late Oligocene to Pleistocene, 2 to 24 million years old. About 12 mi of the line.
Mafic-volcanic. Age: Jurassic, 145 to 202 million years old. About 0.5 mi of the line.
Granodiorite. Age: Permian to Tertiary, 2.6 to 260 million years old. About 0.3 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 Lockwood reaches San Francisco Bay and the Pacific Ocean by way of South Fork Dry Creek, Dry Creek, the Mokelumne, the South Mokelumne, the San Joaquin and New York Slough: about 110 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Lockwood; river miles along the main stem, rounded.
