The Sonoita 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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Sonoita’s center stands about 4,880 ft above sea level. Within three miles the land runs from 4,690 ft to 5,090 ft, a difference of 400 ft: rolling country. The highest named summit within 15 miles is Mount Wrightson, about 9,340 ft, 11 miles west.
Under the town center the state geologic map shows Pliocene to middle Miocene deposits (conglomerate, sandstone), from the Early Miocene to Pleistocene, 2 to 16 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 6×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Conglomerate, sandstone. Age: Early Miocene to Pleistocene, 2 to 16 million years old. About 15 mi of the line.
Rhyolite, sandstone, conglomerate. Age: Early Jurassic to Late Jurassic, 160 to 200 million years old. About 3 mi of the line.
Arenite, conglomerate. Age: Late Jurassic to Late Cretaceous, 80 to 160 million years old. About 3 mi of the line.
Gravel, sand. Age: Late Pliocene to Pleistocene, 0.8 to 3 million years old. About 1 mi of the line.
Sandstone, shale, limestone. Age: Middle Pennsylvanian to Permian, 280 to 310 million years old. About 0.9 mi of the line.
Granite, granodiorite, diorite. Age: Late Cretaceous to Early Eocene, 50 to 82 million years old. About 0.1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.
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.
