The Hamilton City 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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24° on Nov. 13, 1985, the coldest reading for this week of the year since 1903. Next is 25° in 1978.
Hamilton City’s center stands about 150 ft above sea level. Within three miles the land runs from 130 ft to 180 ft, a difference of 50 ft: nearly flat ground.
Under the town center the state geologic map shows Quaternary alluvium and marine deposits (coarse-detrital), from the Pleistocene to Holocene, less than 2.6 million years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 46×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 20 mi of the line.
Sandstone, conglomerate. Age: Miocene to Pleistocene, less than 23 million years old. About 3 mi of the line.
Andesite. Age: Late Oligocene to Pleistocene, 2 to 24 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.
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 City reaches San Francisco Bay and the Pacific Ocean by way of the Sacramento: about 190 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Hamilton City; river miles along the main stem, rounded.
Hamilton City has a hot-summer Mediterranean climate. Summer afternoons average 94° in July; winter nights fall to about 37° in December. About 21 inches of rain fall in a normal year.
On November 14 Hamilton City normally reaches 66° and falls to 43°. The record high is 83°, in 2013; the record low 25°, in 1985. The most rain on this date, 2.26 in, fell in 1953.
Normals 1991–2020 and records since 1903 at Orland, 10 miles west, 100 ft higher. NOAA, through RCC-ACIS.
