The Idaho Springs 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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75° on Nov. 16, 2016, the hottest reading for this week of the year since 1961. Next is 74° in 1999.
Idaho Springs’s center stands about 7,550 ft above sea level. Within three miles the land runs from 7,470 ft to 10,000 ft, a difference of 2,530 ft: mountain country. The highest named summit within 15 miles is Mount Blue Sky, about 14,200 ft, 13 miles south-southwest.
Under the town center the state geologic map shows Biotitic gneiss, schist, and migmatite (biotite-gneiss, schist, migmatite), from the Paleoproterozoic, 1.6 to 2.5 billion 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.
Biotite-gneiss, schist, migmatite. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 12 mi of the line.
Gneiss. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 7 mi of the line.
Alkali-feldspar-granite, granite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 3 mi of the line.
Unconsolidated. Age: Pleistocene, less than 0.5 million years old. About 1 mi of the line.
Granitic, dioritic. Age: Late Cretaceous to Middle Eocene, 40 to 72 million years old. About 0.4 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 Idaho Springs reaches the Gulf of America by way of Clear Creek, the South Platte, the Platte, the Missouri and the Mississippi: about 2,430 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 Idaho Springs; river miles along the main stem, rounded.
Idaho Springs has a warm-summer humid continental climate. Summer afternoons average 81° in July; winter nights fall to about 13° in January. A normal year brings about 81 inches of snow; with the rain, that comes to about 19 inches of water.
On November 14 Idaho Springs normally reaches 52° and falls to 21°. The record high is 74°, in 1999; the record low −10°, in 2014. The most rain on this date, 1.35 in, fell in 1987.
Normals 1991–2020 and records since 1961 at Evergreen, 13 miles southeast, 550 ft lower. NOAA, through RCC-ACIS.
