The Iliff 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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78° on Nov. 14, 1999, the hottest reading for this week of the year since 1893. Next is 77° in 1990.
Iliff’s center stands about 3,840 ft above sea level. Within three miles the land runs from 3,810 ft to 3,960 ft, a difference of 150 ft: gently rolling country. The highest named summit within 15 miles is Kirchnavy Butte, about 4,550 ft, 15 miles northwest.
Under the town center the state geologic map shows Modern alluvium (unconsolidated), from the Quaternary, 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 29×. 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, claystone. Age: Oligocene, 23 to 34 million years old. About 7 mi of the line.
Sand, silt. Age: Quaternary, less than 2.6 million years old. About 5 mi of the line.
Sandstone, conglomerate. Age: Miocene to Pliocene, 2.6 to 23 million years old. About 4 mi of the line.
Gravel, unconsolidated. Age: Pleistocene, 0.2 to 1.6 million years old. About 3 mi of the line.
Sandstone. Age: Miocene, 5.3 to 23 million years old. About 3 mi of the line.
Unconsolidated. Age: Quaternary, less than 2.6 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 Iliff reaches the Gulf of America by way of the South Platte, the Platte, the Missouri and the Mississippi: about 2,220 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 Iliff; river miles along the main stem, rounded.
Iliff has a cold semi-arid climate. Summer afternoons average 88° in July; winter nights fall to about 15° in January. A normal year brings about 37 inches of snow; with the rain, that comes to about 17 inches of water.
On November 14 Iliff normally reaches 51° and falls to 25°. The record high is 78°, in 1999; the record low −8°, in 2014. The most rain on this date, 0.42 in, fell in 1906.
Normals 1991–2020 and records since 1893 at Leroy 5 WSW, 17 miles south-southeast, 620 ft higher. NOAA, through RCC-ACIS.
