The Stevenson Ranch 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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94° on Nov. 12, 2021, the hottest reading for this week of the year since 1949. Next is 92° in 2008.
Stevenson Ranch’s center stands about 1,490 ft above sea level. Within three miles the land runs from 1,080 ft to 2,740 ft, a difference of 1,660 ft: steep hill country. The highest named summit within 15 miles is Magic Mountain, about 4,860 ft, 15 miles east.
Under the town center the state geologic map shows Plio-Pleistocene and Pliocene loosely consolidated deposits (sandstone, conglomerate), from the Miocene to Pleistocene, less than 23 million years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 7×. 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 7 mi of the line.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 5 mi of the line.
Sandstone, mudstone. Age: Oligocene to Pliocene, 2.6 to 34 million years old. About 5 mi of the line.
Sandstone, mudstone. Age: Miocene to Pleistocene, less than 23 million years old. About 3 mi of the line.
Coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 2 mi of the line.
Sandstone, siltstone-mudstone. Age: Late Cretaceous, 66 to 100 million years old. About 0.8 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 1 smaller unit 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 Stevenson Ranch reaches the Pacific Ocean by way of the South Fork Santa Clara and the Santa Clara: about 55 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Stevenson Ranch; river miles along the main stem, rounded.
Stevenson Ranch has a hot semi-arid climate. Summer afternoons average 93° in August; winter nights fall to about 45° in December. About 13 inches of rain fall in a normal year.
Normals 1991–2020 and records since 1949 at Van Nuys Airport, 13 miles south-southeast, 700 ft lower. NOAA, through RCC-ACIS.
