The Broomfield 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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82° on Nov. 17, 2016, the hottest reading for this week of the year since 1984. Next is 82° in 2025.
Broomfield’s center stands about 5,400 ft above sea level. Within three miles the land runs from 5,230 ft to 5,680 ft, a difference of 450 ft: hilly country. The highest named summit within 15 miles is Blue Mountain, about 9,380 ft, 15 miles west-southwest.
Under the town center the state geologic map shows Denver and Arapahoe Fms (sandstone, mudstone, conglomerate), from the Late Cretaceous to Paleocene, 56 to 100 million years old.
The section below crosses 9 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 7×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone, mudstone, conglomerate. Age: Late Cretaceous to Paleocene, 56 to 100 million years old. About 11 mi of the line.
Sandstone, shale, claystone. Age: Late Cretaceous, 66 to 100 million years old. About 6 mi of the line.
Gravel, unconsolidated. Age: Pleistocene, less than 0.5 million years old. About 2 mi of the line.
Granite. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 1 mi of the line.
Gravel, unconsolidated. Age: Pleistocene, 0.2 to 1.6 million years old. About 1 mi of the line.
Unconsolidated. Age: Quaternary, less than 2.6 million 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. 3 smaller units 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 Broomfield reaches the Gulf of America by way of Big Dry Creek, the South Platte, the Platte, the Missouri and the Mississippi: about 2,390 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 Broomfield; river miles along the main stem, rounded.
Broomfield has a humid subtropical climate. Summer afternoons average 91° in July; winter nights fall to about 19° in January. A normal year brings about 45 inches of snow; with the rain, that comes to about 14 inches of water.
On November 14 Broomfield normally reaches 56° and falls to 27°. The record high is 79°, in 1990; the record low 1°, in 2014. The most rain on this date, 0.45 in, fell in 1994.
Normals 1991–2020 and records since 1984 at Northglenn, 4 miles east-southeast. NOAA, through RCC-ACIS.
