The Jasper 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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71° on Nov. 12, 1981, the hottest reading for this week of the year since 1955. Next is 69° in 1970.
Jasper’s center stands about 530 ft above sea level. Within three miles the land runs from 490 ft to 1,610 ft, a difference of 1,120 ft: steep hill country. The highest named summit within 15 miles is Walker Point, about 3,760 ft, 15 miles east-northeast.
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 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 8×. 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.
Mafic-volcanic, felsic-volcanic, clastic. Age: Tertiary, 2.6 to 66 million years old. About 5 mi of the line.
Sand, gravel, silt. Age: Holocene, less than 12,000 years old. About 4 mi of the line.
Basalt, basaltic-andesite. Age: Oligocene to Miocene, 5.3 to 34 million years old. About 4 mi of the line.
Gravel, boulders, clay. Age: Pleistocene to Holocene, less than 2.6 million years old. About 1 mi of the line.
Clay, silt, sand. Age: Pleistocene, less than 2.6 million years old. About 0.9 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 Jasper reaches the Pacific Ocean by way of the Middle Fork Willamette, the Willamette and the Columbia: about 290 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 Jasper; river miles along the main stem, rounded.
Jasper has a warm-summer Mediterranean climate. Summer afternoons average 80° in July; winter nights fall to about 37° in January. About 46 inches of rain fall in a normal year.
On November 14 Jasper normally reaches 52° and falls to 42°. The record high is 69°, in 1999; the record low 22°, in 1978. The most rain on this date, 2.26 in, fell in 2014.
Normals 1991–2020 and records since 1955 at Lookout Point Dam, 9 miles southeast, 180 ft higher. NOAA, through RCC-ACIS.
