The Boulder Flats 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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−25° on Nov. 13, 1916, the coldest reading for this week of the year since 1891. Next is −22° in 1919.
Boulder Flats’s center stands about 5,580 ft above sea level. Within three miles the land runs from 5,420 ft to 6,050 ft, a difference of 630 ft: hilly country. The highest named summit within 15 miles is Mount Arter, about 11,020 ft, 14 miles southwest.
Under the town center the state geologic map shows Gravel, pediment, and fan deposits, from the Pleistocene to Holocene, less than 2.6 million years old.
The section below crosses 11 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.
Clay, silt, sand. Age: Pleistocene to Holocene, less than 2.6 million years old. About 6 mi of the line.
Gravel. Age: Pleistocene to Holocene, less than 2.6 million years old. About 4 mi of the line.
Shale, siltstone. Age: Late Cretaceous, 78 to 83 million years old. About 3 mi of the line.
Claystone. Age: Eocene, 34 to 56 million years old. About 3 mi of the line.
Limestone, dolostone. Age: Late Devonian to Carboniferous, 324 to 384 million years old. About 3 mi of the line.
Dolostone, limestone. Age: Middle Cambrian to Late Ordovician, 445 to 521 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. 5 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 Boulder Flats reaches the Gulf of America by way of Mill Creek, the Little Wind, the Wind River, the Bighorn, the Yellowstone, the Missouri and the Mississippi: about 3,420 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 Boulder Flats; river miles along the main stem, rounded.
Boulder Flats has a warm-summer humid continental climate. Summer afternoons average 88° in July; winter nights fall to about 10° in January. A normal year brings about 88 inches of snow; with the rain, that comes to about 13 inches of water.
On November 14 Boulder Flats normally reaches 45° and falls to 21°. The record high is 71°, in 1894; the record low −14°, in 1959. The most rain on this date, 0.88 in, fell in 1991.
Normals 1991–2020 and records since 1891 from the Lander Area threaded record (Lander Airport, 8 miles south-southeast). NOAA, through RCC-ACIS.
