The Halfway 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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68° on Nov. 12, 1999, the hottest reading for this week of the year since 1936. Next is 67° in 2016.
Halfway’s center stands about 2,650 ft above sea level. Within three miles the land runs from 2,490 ft to 4,560 ft, a difference of 2,070 ft: mountain country. The highest named summit within 15 miles is Red Mountain, about 9,500 ft, 15 miles north-northwest.
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 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.
Basalt. Age: Early Miocene to Middle Miocene, 12 to 23 million years old. About 11 mi of the line.
Sand, gravel, silt. Age: Holocene, less than 12,000 years old. About 4 mi of the line.
Metaandesite, metabasalt, spilite. Age: Permian to Triassic, 202 to 299 million years old. About 3 mi of the line.
Granite, quartz-diorite. Age: Triassic to Jurassic, 145 to 252 million years old. About 2 mi of the line.
Rhyolite, dacite. Age: Early Miocene to Pliocene, 2.6 to 23 million years old. About 1 mi of the line.
Basalt. Age: Early Miocene, 16 to 23 million years old. About 0.7 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 Halfway reaches the Pacific Ocean by way of Sag Creek, Pine Creek, the Snake and the Columbia: about 610 river miles.
Lakes on the way: Lake Umatilla and Hells Canyon Reservoir.
240 miles of the trip are on the Snake.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Halfway; river miles along the main stem, rounded.
Halfway has a dry-summer warm-summer continental climate. Summer afternoons average 90° in July; winter nights fall to about 19° in January. A normal year brings about 62 inches of snow; with the rain, that comes to about 21 inches of water.
On November 14 Halfway normally reaches 46° and falls to 28°. The record high is 67°, in 1999; the record low 5°, in 1978. The most rain on this date, 0.81 in, fell in 2001.
Normals 1991–2020 and records since 1936 at Halfway, here. NOAA, through RCC-ACIS.
