The Cascadia 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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74° on Nov. 14, 1999, the hottest reading for this week of the year since 1969. Next is 73° in 2021.
Cascadia’s center stands about 890 ft above sea level. Within three miles the land runs from 810 ft to 3,010 ft, a difference of 2,200 ft: mountain country. The highest named summit within 15 miles is Twin Buttes, about 5,320 ft, 13 miles east-southeast.
Under the town center the state geologic map shows Tuff (volcanic), from the Tertiary, 2.6 to 66 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 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.
Basalt, basaltic-andesite. Age: Oligocene to Miocene, 5.3 to 34 million years old. About 13 mi of the line.
Basalt, andesite, basaltic-andesite. Age: Early Miocene to Late Miocene, 10 to 17 million years old. About 4 mi of the line.
Mafic-volcanic, felsic-volcanic, clastic. Age: Tertiary, 2.6 to 66 million years old. About 3 mi of the line.
Basalt, basaltic-andesite. Age: Oligocene to Miocene, 5.3 to 34 million years old. About 2 mi of the line.
Hypabyssal-rhyolite, hypabyssal-dacite. Age: Miocene, 5.3 to 23 million years old. About 1 mi of the line.
Volcanic. Age: Tertiary, 2.6 to 66 million years old. About 1 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 Cascadia reaches the Pacific Ocean by way of the South Santiam, the Santiam, the Willamette and the Columbia: about 260 river miles.
Lake on the way: Willamette Falls Hydroelectric Power Reservoir.
100 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Cascadia; river miles along the main stem, rounded.
Cascadia has a warm-summer Mediterranean climate. Summer afternoons average 83° in August; winter nights fall to about 34° in January. About 54 inches of rain fall in a normal year.
On November 14 Cascadia normally reaches 53° and falls to 38°. The record high is 74°, in 1999; the record low 17°, in 1978. The most rain on this date, 1.95 in, fell in 2014.
Normals 1991–2020 and records since 1969 at Foster Dam, 10 miles west, 340 ft lower. NOAA, through RCC-ACIS.
