The Libby 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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69° on Nov. 13, 1999, the hottest reading for this week of the year since 1986. Next is 61° in 1995.
Libby’s center stands about 2,110 ft above sea level. Within three miles the land runs from 2,040 ft to 3,460 ft, a difference of 1,420 ft: steep hill country. The highest named summit within 15 miles is Snowshoe Peak, about 8,550 ft, 13 miles south-southwest.
Under the town center the state geologic map shows Alluvium (gravel, sand, silt), from the Pleistocene to Holocene, less than 1.8 million 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, argillite, metasiltstone. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 8 mi of the line.
Metasiltstone, argillite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 6 mi of the line.
Unconsolidated. Age: Pleistocene to Holocene, less than 1.8 million years old. About 4 mi of the line.
Quartzite, metasiltstone, argillite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 3 mi of the line.
Gravel, sand, silt. Age: Pleistocene to Holocene, less than 1.8 million 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.
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 Libby reaches the Pacific Ocean by way of the Kootenai and the Columbia: about 830 river miles.
Lake on the way: 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 Libby; river miles along the main stem, rounded.
Libby has a warm-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 21° in February. About 17 inches of rain fall in a normal year.
On November 14 Libby normally reaches 43° and falls to 28°. The record high is 56°, in 1999; the record low 8°, in 2014. The most rain on this date, 0.60 in, fell in 2006.
Normals 1991–2020 and records since 1986 at Libby Dam (Base), 11 miles east. NOAA, through RCC-ACIS.
