The Jackson 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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64° on Nov. 15, 1990, the hottest reading for this week of the year since 1905. Next is 63° in 1999.
Jackson’s center stands about 6,240 ft above sea level. Within three miles the land runs from 6,100 ft to 8,420 ft, a difference of 2,320 ft: mountain country. The highest named summit within 15 miles is Buck Mountain, about 11,370 ft, 15 miles north.
Under the town center the state geologic map shows Alluvium and Colluvium (clay, silt, sand), from the Pleistocene to Holocene, less than 2.6 million years old.
The section below crosses 11 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 4×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Clay, silt, sand. Age: Pleistocene to Holocene, less than 2.6 million years old. About 7 mi of the line.
Limestone, dolostone. Age: Late Devonian to Carboniferous, 324 to 384 million years old. About 5 mi of the line.
Sand, gravel, boulders. Age: Pleistocene to Holocene, less than 2.6 million years old. About 4 mi of the line.
Limestone, sandstone. Age: Carboniferous to Permian, 252 to 359 million years old. About 3 mi of the line.
Dolostone, limestone. Age: Middle Cambrian to Late Ordovician, 445 to 521 million years old. About 2 mi of the line.
Sandstone, siltstone. Age: Early Triassic to Jurassic, 145 to 252 million years old. About 1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 5 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 Jackson reaches the Pacific Ocean by way of Flat Creek, the Snake and the Columbia: about 1,260 river miles.
Lakes on the way: American Falls Reservoir, Palisades Reservoir, Lake Umatilla and Brownlee Reservoir.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Jackson; river miles along the main stem, rounded.
Jackson has a warm-summer humid continental climate. Summer afternoons average 79° in July; winter nights fall to about 6° in January. A normal year brings about 78 inches of snow; with the rain, that comes to about 18 inches of water.
On November 14 Jackson normally reaches 38° and falls to 16°. The record high is 62°, in 1999; the record low −12°, in 1922. The most rain on this date, 0.65 in, fell in 1983.
Normals 1991–2020 and records since 1905 at Jackson, here. NOAA, through RCC-ACIS.
