The Lyman 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.
Lyman’s center stands about 110 ft above sea level. Within three miles the land runs from 50 ft to 2,730 ft, a difference of 2,680 ft: mountain country. The highest named summit within 15 miles is South Twin, about 6,810 ft, 13 miles north-northeast.
Under the town center the state geologic map shows Glacial drift, undivided (sand, gravel), from the Pleistocene, less than 2.6 million 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 3×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Graywacke, argillite, phyllite. Age: Middle Jurassic to Eocene, 34 to 175 million years old. About 6 mi of the line.
Phyllite. Age: Jurassic to Early Cretaceous, 100 to 202 million years old. About 5 mi of the line.
Sand, gravel. Age: Pleistocene, less than 2.6 million years old. About 5 mi of the line.
Silt, sand. Age: Holocene, less than 12,000 years old. About 5 mi of the line.
Dunite. Age: Cretaceous to Paleocene, 56 to 145 million years old. About 2 mi of the line.
Arkose. Age: Late Cretaceous to Eocene, 34 to 100 million years old. About 0.8 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 Lyman reaches the Pacific Ocean by way of the Skagit, the South Fork Skagit and Freshwater Slough: about 30 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Lyman; river miles along the main stem, rounded.
Lyman 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 Lyman 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, 8 miles west-southwest. NOAA, through RCC-ACIS.
