The Tarkio 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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Showers likely
−1° on Nov. 12, 2019, the coldest reading for this week of the year since 1893. Next is 0° in 1940.
Tarkio’s center stands about 1,000 ft above sea level. Within three miles the land runs from 900 ft to 1,100 ft, a difference of 200 ft: rolling country. The highest named summit within 15 miles is Brickyard Hill, about 1,170 ft, 10 miles west-northwest.
Under the town center the state geologic map shows Shawnee Group (limestone, shale), from the Carboniferous, 299 to 324 million years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale, siltstone, sandstone. Age: Carboniferous, 299 to 324 million years old. About 11 mi of the line.
Limestone, shale. Age: Carboniferous, 299 to 324 million years old. About 9 mi of the line.
Clay, silt, sand. Age: Holocene, less than 12,000 years old. About 3 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 Tarkio reaches the Gulf of America by way of West Tarkio Creek, the Tarkio, the Missouri and the Mississippi: about 1,690 river miles.
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 Tarkio; river miles along the main stem, rounded.
Tarkio has a hot-summer humid continental climate. Summer afternoons average 87° in July; winter nights fall to about 14° in January. A normal year brings about 30 inches of snow; with the rain, that comes to about 32 inches of water.
On November 14 Tarkio normally reaches 52° and falls to 30°. The record high is 77°, in 1990; the record low 1°, in 1940. The most rain on this date, 2.55 in, fell in 1909.
Normals 1991–2020 and records since 1893 at Auburn 5 ESE, 20 miles west-southwest. NOAA, through RCC-ACIS.
