The Downieville-Lawson-Dumont 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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−16° on Nov. 13, 2014, the coldest reading for this week of the year since 1893. Next is −6° in 1951.
Downieville-Lawson-Dumont’s center stands about 8,020 ft above sea level. Within three miles the land runs from 7,880 ft to 10,900 ft, a difference of 3,020 ft: mountain country. The highest named summit within 15 miles is Grays Peak, about 14,210 ft, 14 miles southwest.
Under the town center the state geologic map shows Glacial drift (unconsolidated), from the Pleistocene, less than 0.5 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 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.
Gneiss. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 11 mi of the line.
Biotite-gneiss, schist, migmatite. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 6 mi of the line.
Alkali-feldspar-granite, granite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 5 mi of the line.
Unconsolidated. Age: Pleistocene, less than 0.5 million years old. About 1 mi of the line.
Granite. Age: Paleoproterozoic, 1.6 to 2.5 billion 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 Downieville-Lawson-Dumont reaches the Gulf of America by way of Clear Creek, the South Platte, the Platte, the Missouri and the Mississippi: about 2,440 river miles.
1,170 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Downieville-Lawson-Dumont; river miles along the main stem, rounded.
Downieville-Lawson-Dumont has a warm-summer humid continental climate. Summer afternoons average 77° in July; winter nights fall to about 15° in December. A normal year brings about 106 inches of snow; with the rain, that comes to about 18 inches of water.
On November 14 Downieville-Lawson-Dumont normally reaches 45° and falls to 22°. The record high is 68°, in 1999; the record low −2°, in 2014. The most rain on this date, 0.41 in, fell in 1978.
Normals 1991–2020 and records since 1893 at Georgetown, 7 miles southwest, 500 ft higher. NOAA, through RCC-ACIS.
