The Seventh Mountain 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 1901. Next is −4° in 1909.
Seventh Mountain’s center stands about 3,920 ft above sea level. Within three miles the land runs from 3,770 ft to 4,400 ft, a difference of 630 ft: hilly country. The highest named summit within 15 miles is Tumalo Mountain, about 7,760 ft, 13 miles west.
Under the town center the state geologic map shows Basalt and basaltic andesite (basaltic-andesite, basalt), from the Early Pliocene to Pleistocene, 1.2 to 3.9 million years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 7×. 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: Pleistocene, less than 2.6 million years old. About 11 mi of the line.
Gravel, sand. Age: Holocene, less than 12,000 years old. About 7 mi of the line.
Basaltic-andesite, basalt. Age: Early Pliocene to Pleistocene, 1.2 to 3.9 million years old. About 4 mi of the line.
Rhyolite, andesite. Age: Pliocene to Pleistocene, less than 5.3 million years old. About 1 mi of the line.
Basaltic-andesite, basalt, andesite. Age: Miocene, 5.3 to 23 million years old. About 0.7 mi of the line.
Basalt, andesite. Age: Miocene to Holocene, less than 23 million years old. About 0.3 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 1 smaller unit 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 Seventh Mountain reaches the Pacific Ocean by way of the Deschutes and the Columbia: about 370 river miles.
Lake on the way: Lake Billy Chinook.
200 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Seventh Mountain; river miles along the main stem, rounded.
Seventh Mountain has a cold semi-arid climate. Summer afternoons average 84° in July; winter nights fall to about 23° in December. A normal year brings about 22 inches of snow; with the rain, that comes to about 11 inches of water.
On November 14 Seventh Mountain normally reaches 50° and falls to 29°. The record high is 69°, in 2016; the record low −9°, in 1955. The most rain on this date, 0.85 in, fell in 1942.
Normals 1991–2020 and records since 1901 at Bend, 6 miles northeast, 260 ft lower. NOAA, through RCC-ACIS.
