The Mount Vernon 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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79° on Nov. 15, 1999, the hottest reading for this week of the year since 1903. Next is 73° in 2016.
Mount Vernon’s center stands about 2,860 ft above sea level. Within three miles the land runs from 2,780 ft to 4,000 ft, a difference of 1,220 ft: steep hill country. The highest named summit within 15 miles is Canyon Mountain, about 7,910 ft, 12 miles east-southeast.
Under the town center the state geologic map shows Alluvial deposits (sand, gravel, silt), from the Holocene, less than 12,000 years old.
The section below crosses 8 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.
Argillite, mudstone, shale. Age: Late Triassic, 227 to 227 million years old. About 6 mi of the line.
Basalt. Age: Early Miocene to Middle Miocene, 12 to 23 million years old. About 4 mi of the line.
Andesite. Age: Paleocene to Early Oligocene, 28 to 66 million years old. About 4 mi of the line.
Sandstone, siltstone, mudstone. Age: Miocene to Pliocene, 2.6 to 23 million years old. About 4 mi of the line.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 2 mi of the line.
Sand, gravel, silt. Age: Holocene, less than 12,000 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. 2 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 Mount Vernon reaches the Pacific Ocean by way of Beech Creek, the John Day and the Columbia: about 450 river miles.
Lake on the way: Lake Umatilla.
230 miles of the trip are on the John Day.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Mount Vernon; river miles along the main stem, rounded.
Mount Vernon has a warm-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 21° in January. A normal year brings about 10 inches of snow; with the rain, that comes to about 12 inches of water.
On November 14 Mount Vernon normally reaches 48° and falls to 26°. The record high is 75°, in 1999; the record low −7°, in 1955. The most rain on this date, 0.55 in, fell in 2006.
Normals 1991–2020 and records since 1903 at John Day, 8 miles east, 200 ft higher. NOAA, through RCC-ACIS.
