The La Porte 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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La Porte’s center stands about 4,990 ft above sea level. Within three miles the land runs from 4,230 ft to 5,780 ft, a difference of 1,550 ft: steep hill country. The highest named summit within 15 miles is Mount Fillmore, about 7,680 ft, 8 miles east-northeast.
Under the town center the state geologic map shows Undivided pre-Cenozoic metavolcanic rocks, unit 2 (undivided) (mafic-volcanic, greenstone), from the Paleozoic to Mesozoic, 66 to 542 million years old.
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 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.
Mafic-volcanic, greenstone. Age: Paleozoic to Mesozoic, 66 to 542 million years old. About 7 mi of the line.
Andesite. Age: Late Oligocene to Pleistocene, 2 to 24 million years old. About 5 mi of the line.
Peridotite, serpentinite. Age: Neoproterozoic to Early Jurassic, 175 to 1,000 million years old. About 3 mi of the line.
Argillite, phyllite. Age: Permian to Jurassic, 145 to 299 million years old. About 2 mi of the line.
Granodiorite. Age: Permian to Tertiary, 2.6 to 260 million years old. About 2 mi of the line.
Mafic-volcanic. Age: Permian to Jurassic, 145 to 299 million years old. About 2 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 La Porte reaches San Francisco Bay and the Pacific Ocean by way of Rabbit Creek, Slate Creek, the North Yuba, the Yuba, the Feather and the Sacramento: about 180 river miles.
Lake on the way: New Bullards Bar Reservoir.
75 miles of the trip are on the Sacramento.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of La Porte; river miles along the main stem, rounded.
