The Willamina 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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67° on Nov. 16, 1976, the hottest reading for this week of the year since 1928. Next is 66° in 1939.
Willamina’s center stands about 230 ft above sea level. Within three miles the land runs from 210 ft to 790 ft, a difference of 580 ft: hilly country. The highest named summit within 15 miles is Laurel Mountain, about 3,600 ft, 12 miles south-southwest.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 6×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Mudstone. Age: Middle Eocene to Late Eocene, 34 to 48 million years old. About 10 mi of the line.
Basalt. Age: Paleocene to Middle Eocene, 38 to 66 million years old. About 9 mi of the line.
Sand, gravel, silt. Age: Holocene, less than 12,000 years old. About 3 mi of the line.
Gabbro. Age: Oligocene, 23 to 34 million years old. About 2 mi of the line.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 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 Willamina reaches the Pacific Ocean by way of Willamina Creek, the South Yamhill, the Yamhill, the Willamette and the Columbia: about 210 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 Willamina; river miles along the main stem, rounded.
Willamina has a warm-summer Mediterranean climate. Summer afternoons average 83° in July; winter nights fall to about 35° in January. About 48 inches of rain fall in a normal year.
On November 14 Willamina normally reaches 52° and falls to 39°. The record high is 64°, in 2001; the record low 15°, in 1978. The most rain on this date, 2.00 in, fell in 1941.
Normals 1991–2020 and records since 1928 at Dallas 2 NE, 13 miles southeast. NOAA, through RCC-ACIS.
