The Pioneer 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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Pioneer’s center stands about 3,030 ft above sea level. Within three miles the land runs from 1,920 ft to 3,570 ft, a difference of 1,650 ft: steep hill country. The highest named summit within 15 miles is Blue Mountain, about 6,020 ft, 13 miles east-southeast.
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 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 4×. 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 9 mi of the line.
Granodiorite. Age: Permian to Tertiary, 2.6 to 260 million years old. About 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 Pioneer reaches San Francisco Bay and the Pacific Ocean by way of South Branch Sutter Creek, Sutter Creek, Dry Creek, the Mokelumne, the South Mokelumne, the San Joaquin and New York Slough: about 110 river miles.
Often dry. About 30% of the way is mapped as streams that run only after rain or snowmelt; the water makes the whole trip in floods.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Pioneer; river miles along the main stem, rounded.
