The Rock Island 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.
Partly cloudy
Chance of showers
Mostly sunny
Partly cloudy
Showers likely
Chance of showers
Partly cloudy
73° on Nov. 15, 2021, the hottest reading for this week of the year since 1931. Next is 69° in 1989.
Rock Island’s center stands about 650 ft above sea level. Within three miles the land runs from 610 ft to 2,970 ft, a difference of 2,360 ft: mountain country. The highest named summit within 15 miles is Wenatchee Mountain, about 6,720 ft, 14 miles west-southwest.
Under the town center the state geologic map shows Younger glacial drift (fine-detrital, coarse-detrital), from the Pleistocene, less than 2.6 million years old.
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 4×. 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. Age: Late Oligocene to Early Pliocene, 3.6 to 28 million years old. About 15 mi of the line.
Silt. Age: Pleistocene, less than 2.6 million years old. About 6 mi of the line.
Conglomerate, volcanic. Age: Middle Miocene to Pliocene, 2.6 to 16 million years old. About 2 mi of the line.
Fine-detrital, coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 1 mi of the line.
Arkose. Age: Late Cretaceous to Eocene, 34 to 100 million years old. About 0.6 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 Rock Island reaches the Pacific Ocean by way of the Columbia: about 450 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 Rock Island; river miles along the main stem, rounded.
Rock Island has a dry-summer hot-summer continental climate. Summer afternoons average 89° in July; winter nights fall to about 26° in January. A normal year brings about 16 inches of snow; with the rain, that comes to about 9 inches of water.
On November 14 Rock Island normally reaches 47° and falls to 33°. The record high is 66°, in 2015; the record low 6°, in 1955. The most rain on this date, 0.86 in, fell in 1981.
Normals 1991–2020 and records since 1931 at Wenatchee, 9 miles west-northwest. NOAA, through RCC-ACIS.
