The Trego 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.
Mostly cloudy
Chance of showers
Chance of showers
Chance of showers
Partly cloudy
Mostly cloudy
Mostly cloudy
Trego’s center stands about 3,660 ft above sea level. Within three miles the land runs from 3,230 ft to 4,590 ft, a difference of 1,360 ft: steep hill country. The highest named summit within 15 miles is Krag Peak, about 7,460 ft, 14 miles north-northeast.
Under the town center the state geologic map shows Piegan Group: Helena and Wallace Formations (quartzite, metasiltstone, argillite), from the Mesoproterozoic, 1 to 1.6 billion years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 5×. 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 11 mi of the line.
Unconsolidated. Age: Pleistocene to Holocene, less than 1.8 million years old. About 7 mi of the line.
Metasiltstone, argillite, quartzite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 4 mi of the line.
Quartzite, argillite, metasiltstone. Age: Mesoproterozoic, 1 to 1.6 billion 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 Trego reaches the Pacific Ocean by way of Edna Creek, Fortine Creek, the Tobacco, the Kootenai and the Columbia: about 920 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 Trego; river miles along the main stem, rounded.
