The Steptoe 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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−14° on Nov. 15, 1955, the coldest reading for this week of the year since 1893. Next is 0° in 1916.
Steptoe’s center stands about 2,380 ft above sea level. Within three miles the land runs from 2,220 ft to 2,910 ft, a difference of 690 ft: hilly country. The highest named summit within 15 miles is Kamiak Butte, about 3,620 ft, 13 miles southeast.
Under the town center the state geologic map shows Quaternary nonmarine deposits (silt), from the Pleistocene, less than 2.6 million years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 20×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Silt. Age: Pleistocene, less than 2.6 million years old. About 20 mi of the line.
Argillite, siltstone. Age: Mesoproterozoic to Early Cambrian, 521 to 1,600 million years old. About 2 mi of the line.
Silt, sand. Age: Holocene, less than 12,000 years old. About 1 mi of the line.
Basalt. Age: Late Oligocene to Early Pliocene, 3.6 to 28 million years old. About 0.8 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 Steptoe reaches the Pacific Ocean by way of Dry Creek, the Palouse, the Snake and the Columbia: about 470 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 Steptoe; river miles along the main stem, rounded.
Steptoe has a dry-summer warm-summer continental climate. Summer afternoons average 86° in August; winter nights fall to about 24° in December. A normal year brings about 26 inches of snow; with the rain, that comes to about 18 inches of water.
On November 14 Steptoe normally reaches 46° and falls to 30°. The record high is 65°, in 1999; the record low −3°, in 1955. The most rain on this date, 0.78 in, fell in 1903.
Normals 1991–2020 and records since 1893 at Rosalia, 16 miles north. NOAA, through RCC-ACIS.
