The Mammoth 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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65° on Nov. 12, 2016, the hottest reading for this week of the year since 1894. Next is 64° in 1999.
Mammoth’s center stands about 6,040 ft above sea level. Within three miles the land runs from 5,600 ft to 8,380 ft, a difference of 2,780 ft: mountain country. The highest named summit within 15 miles is Electric Peak, about 10,860 ft, 7 miles west-northwest.
Under the town center the state geologic map shows Undivided surficial deposits (unconsolidated), from the Pleistocene to Holocene, less than 2.6 million years old.
The section below crosses 10 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.
Schist, gneiss. Age: Archean. About 7 mi of the line.
Rhyolite. Age: Pleistocene, less than 2.6 million years old. About 5 mi of the line.
Unconsolidated. Age: Pleistocene to Holocene, less than 2.6 million years old. About 4 mi of the line.
Basalt, plutonic. Age: Pleistocene, less than 2.6 million years old. About 3 mi of the line.
Conglomerate-sandstone, mudstone. Age: Late Cretaceous, 66 to 84 million years old. About 1 mi of the line.
Age: Pleistocene to Holocene, less than 1.8 million years old. About 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. 4 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 Mammoth reaches the Gulf of America by way of the Yellowstone, the Missouri and the Mississippi: about 3,300 river miles.
Lakes on the way: Lake Oahe, Lake Sakakawea, Lake Sharpe and Lake Francis Case.
1,170 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Mammoth; river miles along the main stem, rounded.
Mammoth has a warm-summer humid continental climate. Summer afternoons average 81° in July; winter nights fall to about 12° in January. A normal year brings about 72 inches of snow; with the rain, that comes to about 15 inches of water.
On November 14 Mammoth normally reaches 40° and falls to 20°. The record high is 61°, in 1953; the record low −7°, in 1955. The most rain on this date, 0.32 in, fell in 1991.
Normals 1991–2020 and records since 1894 at Yellowstone Park Mammoth, here, 160 ft higher. NOAA, through RCC-ACIS.
