The Lake Arrowhead 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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Lake Arrowhead’s center stands about 5,250 ft above sea level. Within three miles the land runs from 3,720 ft to 6,120 ft, a difference of 2,400 ft: mountain country. The highest named summit within 15 miles is Butler Peak, about 8,470 ft, 10 miles east.
Under the town center the state geologic map shows Mesozoic granitic rocks, unit 3 (Sierra Nevada, Death Valley area, Northern Mojave Desert and Transverse Ranges) (granodiorite), from the Permian to Tertiary, 2.6 to 260 million years old.
The section below crosses 6 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.
Granodiorite. Age: Permian to Tertiary, 2.6 to 260 million years old. About 17 mi of the line.
Gneiss. Age: Paleoproterozoic to Miocene, 5.3 to 2,500 million years old. About 3 mi of the line.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 2 mi of the line.
Mica-schist. Age: Late Cretaceous to Eocene, 34 to 100 million years old. About 0.6 mi of the line.
Limestone, sandstone, dolostone. Age: Neoproterozoic to Jurassic, 145 to 1,000 million years old. About 0.5 mi of the line.
Coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 0.4 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 Lake Arrowhead reaches the desert basins of Owens Valley and Death Valley by way of Willow Creek, Deep Creek and the Mojave: about 130 river miles. The desert basins of Owens Valley and Death Valley has no outlet to the sea: the water leaves only by evaporating or soaking into the ground.
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 Lake Arrowhead; river miles along the main stem, rounded.
