The Great Falls 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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74° on Nov. 12, 1999, the hottest reading for this week of the year since 1891. Next is 72° in 1990.
Great Falls’s center stands about 3,330 ft above sea level. Within three miles the land runs from 3,300 ft to 3,650 ft, a difference of 350 ft: rolling country. The highest named summit within 15 miles is Red Butte, about 4,150 ft, 10 miles south-southeast.
Under the town center the state geologic map shows Upper Kootenai Formation (sandstone), from the Early Cretaceous, 100 to 125 million years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 23×. 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. Age: Early Cretaceous, 113 to 125 million years old. About 6 mi of the line.
Shale. Age: Late Cretaceous, 94 to 100 million years old. About 5 mi of the line.
Black-shale, siltstone, sandstone. Age: Early Cretaceous, 100 to 113 million years old. About 4 mi of the line.
Sandstone. Age: Early Cretaceous, 100 to 125 million years old. About 3 mi of the line.
Sandstone, shale, siltstone. Age: Early Cretaceous, 100 to 113 million years old. About 2 mi of the line.
Gravel, sand, silt. Age: Pleistocene to Holocene, less than 1.8 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. 1 smaller unit 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 Great Falls reaches the Gulf of America by way of the Missouri and the Mississippi: about 3,270 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 Great Falls; river miles along the main stem, rounded.
Great Falls has a cold semi-arid climate. Summer afternoons average 84° in July; winter nights fall to about 15° in January. A normal year brings about 66 inches of snow; with the rain, that comes to about 15 inches of water.
On November 14 Great Falls normally reaches 44° and falls to 24°. The record high is 71°, in 1999; the record low −16°, in 2014. The most rain on this date, 0.44 in, fell in 1955.
Normals 1991–2020 and records since 1891 from the Great Falls Area threaded record (Great Falls Airport, 4 miles west-southwest, 340 ft higher). NOAA, through RCC-ACIS.
