The Hamilton 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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3° on Nov. 14, 1955, the coldest reading for this week of the year since 1896. Next is 8° in 1911.
Hamilton’s center stands about 100 ft above sea level. Within three miles the land runs from 70 ft to 3,460 ft, a difference of 3,390 ft: mountain country. The highest named summit within 15 miles is South Twin, about 6,810 ft, 13 miles north.
The section below crosses 7 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.
Phyllite. Age: Jurassic to Early Cretaceous, 100 to 202 million years old. About 9 mi of the line.
Sand, gravel. Age: Pleistocene, less than 2.6 million years old. About 4 mi of the line.
Silt, sand. Age: Holocene, less than 12,000 years old. About 4 mi of the line.
Arkose. Age: Late Cretaceous to Eocene, 34 to 100 million years old. About 2 mi of the line.
Graywacke, argillite, phyllite. Age: Middle Jurassic to Eocene, 34 to 175 million years old. About 2 mi of the line.
Dunite. Age: Cretaceous to Paleocene, 56 to 145 million 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. 1 smaller unit 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 Hamilton reaches the Pacific Ocean by way of the Skagit, the South Fork Skagit and Freshwater Slough: about 40 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Hamilton; river miles along the main stem, rounded.
Hamilton has a warm-summer Mediterranean climate. Summer afternoons average 75° in August; winter nights fall to about 34° in December. A normal year brings about 6 inches of snow; with the rain, that comes to about 48 inches of water.
On November 14 Hamilton normally reaches 51° and falls to 39°. The record high is 66°, in 1923; the record low 3°, in 1955. The most rain on this date, 2.45 in, fell in 1998.
Normals 1991–2020 and records since 1896 at Sedro-Woolley, 11 miles west. NOAA, through RCC-ACIS.
