The Piedmont 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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83° on Nov. 15, 2008, the hottest reading for this week of the year since 1970. Next is 81° in 2010.
Piedmont’s center stands about 330 ft above sea level. Within three miles the land runs from 10 ft to 1,490 ft, a difference of 1,480 ft: steep hill country. The highest named summit within 15 miles is Vollmer Peak, about 1,890 ft, 4 miles north.
Under the town center the state geologic map shows Franciscan Complex, unit 1 (Coast Ranges) (sandstone, mudstone), from the Jurassic to Cretaceous, 66 to 202 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 11×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone, conglomerate. Age: Miocene to Pleistocene, less than 23 million years old. About 4 mi of the line.
Sandstone, mudstone. Age: Oligocene to Pliocene, 2.6 to 34 million years old. About 4 mi of the line.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 3 mi of the line.
Coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 3 mi of the line.
Sandstone, mudstone. Age: Jurassic to Cretaceous, 66 to 202 million years old. About 2 mi of the line.
Siltstone-mudstone. Age: Early Cretaceous to Late Cretaceous, 66 to 145 million years old. About 1 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.
Rain that falls on Piedmont runs straight into San Francisco Bay and the Pacific Ocean.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Piedmont; river miles along the main stem, rounded.
Piedmont has a warm-summer Mediterranean climate. Summer afternoons average 75° in September; winter nights fall to about 45° in January. About 23 inches of rain fall in a normal year.
On November 14 Piedmont normally reaches 66° and falls to 50°. The record high is 82°, in 2008; the record low 37°, in 1978. The most rain on this date, 0.82 in, fell in 1972.
Normals 1991–2020 and records since 1970 at Oakland Museum, 3 miles southwest, 300 ft lower. NOAA, through RCC-ACIS.
