The Summit 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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17° on Nov. 16, 2014, the coldest reading for this week of the year since 1936. Next is 19° in 1978.
Summit’s center stands about 730 ft above sea level. Within three miles the land runs from 250 ft to 1,190 ft, a difference of 940 ft: steep hill country. The highest named summit within 15 miles is Marys Peak, about 4,080 ft, 9 miles south.
Under the town center the state geologic map shows Alluvial deposits (sand, gravel, silt), from the Holocene, less than 12,000 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 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.
Sandstone. Age: Middle Eocene, 38 to 48 million years old. About 18 mi of the line.
Basalt. Age: Paleocene to Middle Eocene, 38 to 66 million years old. About 2 mi of the line.
Gabbro. Age: Oligocene, 23 to 34 million years old. About 2 mi of the line.
Sand, gravel, silt. Age: Holocene, less than 12,000 years old. About 1 mi of the line.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 0.5 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 Summit reaches the Pacific Ocean by way of the Marys, the Willamette and the Columbia: about 270 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 Summit; river miles along the main stem, rounded.
Summit has a warm-summer Mediterranean climate. Summer afternoons average 83° in August; winter nights fall to about 28° in January. A normal year brings about 5 inches of snow; with the rain, that comes to about 69 inches of water.
On November 14 Summit normally reaches 53° and falls to 31°. The record high is 69°, in 1999; the record low 20°, in 1978. The most rain on this date, 3.37 in, fell in 1942.
Normals 1991–2020 and records since 1936 at Corvallis Water Bureau, 11 miles south-southeast, 140 ft lower. NOAA, through RCC-ACIS.
