The Roslyn 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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8.00 inches of rain fell in two days, the most for this week of the year since records began in 1944. The next wettest, 6.52 inches, fell in 1958.
Roslyn’s center stands about 4,550 ft above sea level. Within three miles the land runs from 2,140 ft to 4,930 ft, a difference of 2,790 ft: mountain country. The highest named summit within 15 miles is Hawkins Mountain, about 7,040 ft, 14 miles north-northeast.
Under the town center the state geologic map shows Upper Eocene volcanic rocks (basalt, basaltic-andesite), from the Late Eocene to Oligocene, 23 to 38 million years old.
The section below crosses 9 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.
Arkose. Age: Late Cretaceous to Eocene, 34 to 100 million years old. About 10 mi of the line.
Basalt, basaltic-andesite. Age: Late Eocene to Oligocene, 23 to 38 million years old. About 4 mi of the line.
Silt, sand. Age: Holocene, less than 12,000 years old. About 3 mi of the line.
Phyllite. Age: Jurassic to Early Cretaceous, 100 to 202 million years old. About 2 mi of the line.
Schist. Age: Triassic to Early Cretaceous, 100 to 252 million years old. About 2 mi of the line.
Arkose. Age: Eocene to Early Oligocene, 28 to 56 million 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. 3 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 Roslyn reaches the Pacific Ocean by way of Domerie Creek, the Cle Elum, the Yakima and the Columbia: about 530 river miles.
Lake on the way: Lake Umatilla.
210 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Roslyn; river miles along the main stem, rounded.
Roslyn has a dry-summer warm-summer continental climate. Summer afternoons average 69° in August; winter nights fall to about 24° in December. About 85 inches of rain fall in a normal year.
On November 14 Roslyn normally reaches 38° and falls to 30°. The record high is 58°, in 1969; the record low −3°, in 1955. The most rain on this date, 1.87 in, fell in 1977.
Normals 1991–2020 and records since 1944 at Stampede Pass, 9 miles west, 590 ft lower. NOAA, through RCC-ACIS.
