The Summit 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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92° on Nov. 11, 1999, the hottest reading for this week of the year since 1894. Next is 92° in 2020.
Summit’s center stands about 2,610 ft above sea level. Within three miles the land runs from 2,530 ft to 2,730 ft, a difference of 200 ft: gently rolling country. The highest named summit within 15 miles is Golden Gate Mountain, about 4,190 ft, 14 miles northwest.
Under the town center the state geologic map shows Holocene river alluvium (sand, gravel), from the Holocene, less than 10,000 years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 18×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sand, silt, clay. Age: Pleistocene to Holocene, less than 2 million years old. About 12 mi of the line.
Gravel, sand. Age: Late Pliocene to Pleistocene, 0.8 to 3 million years old. About 6 mi of the line.
Sand, gravel. Age: Holocene, less than 10,000 years old. About 3 mi of the line.
Conglomerate, sandstone. Age: Early Oligocene to Late Miocene, 11 to 32 million years old. About 2 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.
Summit has a hot desert climate. Summer afternoons average 101° in June; winter nights fall to about 41° in January. About 11 inches of rain fall in a normal year.
On November 14 Summit normally reaches 76° and falls to 48°. The record high is 90°, in 1999; the record low 24°, in 1916. The most rain on this date, 1.57 in, fell in 1968.
Normals 1991–2020 and records since 1894 from the Tucson Area threaded record (Tucson International Airport, 5 miles north). NOAA, through RCC-ACIS.
