The Sierra Vista 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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22° on Nov. 14, 2018, the coldest reading for this week of the year since 1982. Next is 25° in 1985.
Sierra Vista’s center stands about 4,640 ft above sea level. Within three miles the land runs from 4,450 ft to 4,970 ft, a difference of 520 ft: hilly country. The highest named summit within 15 miles is Miller Peak, about 9,410 ft, 11 miles south.
Under the town center the state geologic map shows Quaternary surficial deposits, undivided (sand, silt, clay), from the Pleistocene to Holocene, less than 2 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.
Sand, silt, clay. Age: Pleistocene to Holocene, less than 2 million years old. About 11 mi of the line.
Conglomerate, sandstone. Age: Early Miocene to Pleistocene, 2 to 16 million years old. About 6 mi of the line.
Granite. Age: Mesoproterozoic, 1.4 to 1.4 billion years old. About 3 mi of the line.
Diorite, alkali-granite, granodiorite. Age: Early Jurassic to Late Jurassic, 150 to 180 million years old. About 2 mi of the line.
Sandstone, shale, limestone. Age: Early Cambrian to Late Mississippian, 330 to 540 million years old. About 2 mi of the line.
Rhyolite, sandstone, conglomerate. Age: Early Jurassic to Late Jurassic, 160 to 200 million years old. About 0.9 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 Sierra Vista reaches the Gulf of California by way of the Babocomari, the San Pedro, the Gila and the Colorado: about 590 river miles.
330 miles of the trip are on the Gila.
Often dry. About 60% of the way is mapped as streams that run only after rain or snowmelt; the water makes the whole trip in floods.
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 Sierra Vista; river miles along the main stem, rounded.
Sierra Vista has a cold semi-arid climate. Summer afternoons average 94° in June; winter nights fall to about 30° in January. About 13 inches of rain fall in a normal year.
On November 14 Sierra Vista normally reaches 70° and falls to 37°. The record high is 86°, in 2017; the record low 22°, in 2018. The most rain on this date, 0.39 in, fell in 2004.
Normals 1991–2020 and records since 1982 at Sierra Vista, here. NOAA, through RCC-ACIS.
