The Clark Fork 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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67° on Nov. 12, 1999, the hottest reading for this week of the year since 1956. Next is 61° in 2021.
Clark Fork’s center stands about 2,100 ft above sea level. Within three miles the land runs from 2,060 ft to 4,160 ft, a difference of 2,100 ft: mountain country. The highest named summit within 15 miles is Scotchman Peak, about 6,930 ft, 5 miles northeast.
Under the town center the state geologic map shows Alluvial deposits (gravel, sand, silt), from the Quaternary, 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.
Quartzite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 4 mi of the line.
Metasiltstone, quartzite, argillite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 4 mi of the line.
Metasiltstone, quartzite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 3 mi of the line.
Gravel, sand, silt. Age: Quaternary, less than 2.6 million years old. About 3 mi of the line.
Quartzite, argillite, metasiltstone. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 3 mi of the line.
Metasiltstone, argillite. Age: Mesoproterozoic, 1 to 1.6 billion 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 Clark Fork reaches the Pacific Ocean by way of Mosquito Creek, the Clark Fork, the Pend Oreille and the Columbia: about 860 river miles.
Lakes on the way: Lake Pend Oreille and Lake Umatilla.
460 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Clark Fork; river miles along the main stem, rounded.
Clark Fork has a dry-summer warm-summer continental climate. Summer afternoons average 81° in July; winter nights fall to about 24° in January. About 31 inches of rain fall in a normal year.
On November 14 Clark Fork normally reaches 42° and falls to 31°. The record high is 60°, in 2021; the record low 11°, in 2014. The most rain on this date, 0.83 in, fell in 1966.
Normals 1991–2020 and records since 1956 at Cabinet Gorge, 7 miles southeast. NOAA, through RCC-ACIS.
