The Summerlin South 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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85° on Nov. 11, 1973, the hottest reading for this week of the year since 1937. Next is 82° in 1981.
Summerlin South’s center stands about 2,890 ft above sea level. Within three miles the land runs from 2,580 ft to 3,700 ft, a difference of 1,120 ft: steep hill country. The highest named summit within 15 miles is Potosi Mountain, about 8,460 ft, 14 miles southwest.
Under the town center the state geologic map shows Alluvium, undifferentiated (coarse-detrital, fine-detrital), from the Pleistocene to Holocene, less than 2.6 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 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.
Coarse-detrital, fine-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 17 mi of the line.
Dolostone, limestone. Age: Cambrian to Middle Devonian, 384 to 497 million years old. About 3 mi of the line.
Limestone, dolostone, shale. Age: Permian, 260 to 299 million years old. About 2 mi of the line.
Bentonite, siltstone, sandstone. Age: Late Triassic to Early Jurassic, 175 to 237 million years old. About 1 mi of the line.
Sandstone. Age: Jurassic, 145 to 202 million years old. About 0.5 mi of the line.
Limestone. Age: Carboniferous, 324 to 359 million years old. About 0.5 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 Summerlin South reaches the Gulf of California by way of Flamingo Wash, Las Vegas Wash and the Colorado: about 480 river miles.
Lakes on the way: Lake Mead, Lake Mohave and Lake Havasu.
290 miles of the trip are on the Colorado.
Seldom reaches the sea. Dams and canals now take nearly all of the Colorado before its old delta in Mexico.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Summerlin South; river miles along the main stem, rounded.
Summerlin South has a hot desert climate. Summer afternoons average 105° in July; winter nights fall to about 40° in December. About 4 inches of rain fall in a normal year.
On November 14 Summerlin South normally reaches 68° and falls to 48°. The record high is 81°, in 1995; the record low 22°, in 1938. The most rain on this date, 0.23 in, fell in 1965.
Normals 1991–2020 and records since 1937 from the Las Vegas Area threaded record (Harry Reid International Airport, 10 miles east-southeast, 720 ft lower). NOAA, through RCC-ACIS.
