The Waterloo 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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74° on Nov. 14, 1999, the hottest reading for this week of the year since 1969. Next is 73° in 2021.
Waterloo’s center stands about 410 ft above sea level. Within three miles the land runs from 370 ft to 1,160 ft, a difference of 790 ft: hilly country. The highest named summit within 15 miles is Bald Peter, about 4,040 ft, 12 miles east.
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 8 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 6×. 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: Oligocene to Miocene, 5.3 to 34 million years old. About 9 mi of the line.
Clay, silt, sand. Age: Pleistocene, less than 2.6 million years old. About 4 mi of the line.
Mafic-volcanic, felsic-volcanic, clastic. Age: Tertiary, 2.6 to 66 million years old. About 3 mi of the line.
Basalt, basaltic-andesite. Age: Oligocene to Miocene, 5.3 to 34 million years old. About 2 mi of the line.
Gravel, boulders, clay. Age: Pleistocene to Holocene, less than 2.6 million years old. About 2 mi of the line.
Sand, gravel, silt. Age: Holocene, less than 12,000 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. 2 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 Waterloo reaches the Pacific Ocean by way of Vail Creek, the South Santiam, the Santiam, the Willamette and the Columbia: about 240 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 Waterloo; river miles along the main stem, rounded.
Waterloo has a warm-summer Mediterranean climate. Summer afternoons average 83° in August; winter nights fall to about 34° in January. About 54 inches of rain fall in a normal year.
On November 14 Waterloo normally reaches 53° and falls to 38°. The record high is 74°, in 1999; the record low 17°, in 1978. The most rain on this date, 1.95 in, fell in 2014.
Normals 1991–2020 and records since 1969 at Foster Dam, 9 miles southeast, 140 ft higher. NOAA, through RCC-ACIS.
