The Brooks 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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−29° on Nov. 16, 1959, the coldest reading for this week of the year since 1896. Next is −24° in 1986.
Brooks’s center stands about 3,950 ft above sea level. Within three miles the land runs from 3,790 ft to 4,300 ft, a difference of 510 ft: hilly country. The highest named summit within 15 miles is Judith Peak, about 6,410 ft, 9 miles east.
Under the town center the state geologic map shows Marias River Formation (shale, dolostone, limestone), from the Late Cretaceous, 84 to 100 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 7×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Age: Late Miocene to Holocene, less than 7.2 million years old. About 7 mi of the line.
Shale, dolostone, limestone. Age: Late Cretaceous, 84 to 100 million years old. About 5 mi of the line.
Shale, sandstone. Age: Early Cretaceous to Late Cretaceous, 94 to 113 million years old. About 3 mi of the line.
Granitic. Age: Cretaceous to Tertiary, 2.6 to 145 million years old. About 3 mi of the line.
Shale, sandstone. Age: Early Cretaceous, 100 to 113 million years old. About 2 mi of the line.
Mudstone, siltstone, sandstone. Age: Early Cretaceous, 100 to 133 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 Brooks reaches the Gulf of America by way of Warm Spring Creek, the Judith, the Missouri and the Mississippi: about 3,220 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 Brooks; river miles along the main stem, rounded.
Brooks has a warm-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 13° in January. About 17 inches of rain fall in a normal year.
On November 14 Brooks normally reaches 44° and falls to 21°. The record high is 72°, in 1999; the record low −21°, in 1955. The most rain on this date, 0.25 in, fell in 2011.
Normals 1991–2020 and records since 1896 at Lewistown Airport, 11 miles south, 180 ft higher. NOAA, through RCC-ACIS.
