The Pinnacle 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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64° on Nov. 15, 2001, the hottest reading for this week of the year since 1947. Next is 63° in 1999.
Pinnacle’s center stands about 3,690 ft above sea level. Within three miles the land runs from 3,530 ft to 6,510 ft, a difference of 2,980 ft: mountain country. The highest named summit within 15 miles is Mount Stimson, about 10,060 ft, 11 miles north.
Under the town center the state geologic map shows Upper Missoula Group: McNamara, Bonner, and Mount Shields Formations; locally includes lower Libby Formation in northwestern Montana (metasiltstone, argillite, quartzite), from the Mesoproterozoic, 1 to 1.6 billion years old.
The section below crosses 6 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.
Quartzite, metasiltstone, argillite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 9 mi of the line.
Quartzite, argillite, metasiltstone. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 6 mi of the line.
Metasiltstone, argillite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 3 mi of the line.
Metasiltstone, argillite, quartzite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 2 mi of the line.
Metasiltstone, argillite, quartzite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 2 mi of the line.
Unconsolidated. 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.
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 Pinnacle reaches the Pacific Ocean by way of the Middle Fork Flathead, the Flathead, the Clark Fork, the Pend Oreille and the Columbia: about 1,150 river miles.
Lakes on the way: Flathead Lake, Lake Pend Oreille, Lake Umatilla and Noxon Rapids Reservoir.
460 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Pinnacle; river miles along the main stem, rounded.
Pinnacle has a dry-summer warm-summer continental climate. Summer afternoons average 82° in July; winter nights fall to about 20° in January. About 35 inches of rain fall in a normal year.
On November 14 Pinnacle normally reaches 38° and falls to 28°. The record high is 62°, in 1990; the record low −4°, in 1955. The most rain on this date, 1.91 in, fell in 1983.
Normals 1991–2020 and records since 1947 at Hungry Horse Dam, 17 miles west, 530 ft lower. NOAA, through RCC-ACIS.
