The Olympia 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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75° on Nov. 11, 2024, the hottest reading for this week of the year since 1924. Next is 72° in 1931.
Olympia’s center stands about 110 ft below sea level. Within three miles the land runs from 40 ft to 330 ft, a difference of 290 ft: rolling country. The highest named summit within 15 miles is Sand Mountain, about 410 ft, 8 miles south.
Under the town center the state geologic map shows Alluvial Valley Swamp (sand, gravel), from the Quaternary, less than 2.6 million 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 23×. 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, sand. Age: Late Cretaceous, 66 to 72 million years old. About 10 mi of the line.
Sand. Age: Cretaceous, 66 to 145 million years old. About 8 mi of the line.
Sand, gravel. Age: Cretaceous, 66 to 145 million years old. About 3 mi of the line.
Sand, clay. Age: Pliocene, 2.6 to 5.3 million years old. About 2 mi of the line.
Sand, gravel. Age: Quaternary, less than 2.6 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.
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 Olympia reaches the Atlantic Ocean by way of the Congaree, the Santee and the South Santee: about 180 river miles.
Lake on the way: Lib Pines Lake.
70 miles of the trip are on the Santee.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Olympia; river miles along the main stem, rounded.
Olympia has a oceanic climate. Summer afternoons average 78° in July; winter nights fall to about 28° in January. A normal year brings about 7 inches of snow; with the rain, that comes to about 74 inches of water.
On November 14 Olympia normally reaches 55° and falls to 38°. The record high is 72°, in 1931; the record low 16°, in 2019. The most rain on this date, 2.40 in, fell in 1961.
Normals 1991–2020 and records since 1924 from the Caesars Head Area threaded record (Columbia Metropolitan Airport, 5 miles west-southwest, 330 ft higher). NOAA, through RCC-ACIS.
