The Bynum 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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−30° on Nov. 13, 1955, the coldest reading for this week of the year since 1893. Next is −28° in 1959.
Bynum’s center stands about 3,970 ft above sea level. Within three miles the land runs from 3,890 ft to 4,270 ft, a difference of 380 ft: rolling country. The highest named summit within 15 miles is Pine Butte, about 5,000 ft, 14 miles southwest.
Under the town center the state geologic map shows Virgelle and Telegraph Creek Formations (sandstone, siltstone, shale), from the Late Cretaceous, 72 to 87 million years old.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 20×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone, siltstone, mudstone. Age: Late Cretaceous, 66 to 84 million years old. About 8 mi of the line.
Age: Pleistocene to Holocene, less than 1.8 million years old. About 7 mi of the line.
Sandstone, siltstone, shale. Age: Late Cretaceous, 72 to 87 million years old. About 5 mi of the line.
Shale, limestone, dolostone. Age: Late Cretaceous, 84 to 90 million years old. About 3 mi of the line.
Age: Late Miocene to Holocene, less than 7.2 million years old. About 0.4 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 Bynum reaches the Gulf of America by way of Foster Creek, Muddy Creek, the Teton, the Marias, the Missouri and the Mississippi: about 3,370 river miles.
Lakes on the way: Lake Oahe, Lake Sakakawea, Lake Fort Peck and Lake Sharpe.
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 Bynum; river miles along the main stem, rounded.
Bynum has a cold semi-arid climate. Summer afternoons average 82° in July; winter nights fall to about 14° in January. A normal year brings about 48 inches of snow; with the rain, that comes to about 12 inches of water.
On November 14 Bynum normally reaches 45° and falls to 22°. The record high is 73°, in 1999; the record low −17°, in 2014. The most rain on this date, 0.40 in, fell in 1897.
Normals 1991–2020 and records since 1893 at Choteau, 12 miles south-southeast, 120 ft lower. NOAA, through RCC-ACIS.
