The St. Ignatius 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.
St. Ignatius’s center stands about 2,930 ft above sea level. Within three miles the land runs from 2,740 ft to 3,770 ft, a difference of 1,030 ft: steep hill country. The highest named summit within 15 miles is McDonald Peak, about 9,710 ft, 9 miles east-northeast.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 3×. 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 8 mi of the line.
Age: Pleistocene to Holocene, less than 1.8 million years old. About 6 mi of the line.
Quartzite, argillite, metasiltstone. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 4 mi of the line.
Gravel, sand, silt. Age: Pleistocene to Holocene, less than 1.8 million years old. About 3 mi of the line.
Unconsolidated. Age: Pleistocene to Holocene, less than 1.8 million years old. About 2 mi of the line.
Metasiltstone, argillite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 0.9 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 1 smaller unit 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 St. Ignatius reaches the Pacific Ocean by way of Mission Creek, the Flathead, the Clark Fork, the Pend Oreille and the Columbia: about 1,000 river miles.
Lakes on the way: 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 St. Ignatius; river miles along the main stem, rounded.