The Larkspur 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.
Partly cloudy
Mostly sunny
Partly cloudy
Partly cloudy
Mostly sunny; cooler
Partly cloudy
Chance of showers
75° on Nov. 12, 1999, the hottest reading for this week of the year since 1996. Next is 75° in 2025.
Larkspur’s center stands about 6,700 ft above sea level. Within three miles the land runs from 6,580 ft to 7,330 ft, a difference of 750 ft: hilly country. The highest named summit within 15 miles is Devils Head, about 9,680 ft, 12 miles west.
Under the town center the state geologic map shows Upper part of Dawson Arkose (arkose, conglomerate, shale), from the Paleocene to Eocene, 34 to 66 million years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 6×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Arkose, conglomerate, shale. Age: Paleocene to Eocene, 34 to 66 million years old. About 12 mi of the line.
Granite, alkali-feldspar-granite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 9 mi of the line.
Sandstone, claystone. Age: Oligocene, 23 to 34 million years old. About 3 mi of the line.
Volcanic. Age: Late Eocene, 35 to 36 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.
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 Larkspur reaches the Gulf of America by way of East Plum Creek, West Plum Creek, the South Platte, the Platte, the Missouri and the Mississippi: about 2,450 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 Larkspur; river miles along the main stem, rounded.
Larkspur has a warm-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 17° in December. A normal year brings about 75 inches of snow; with the rain, that comes to about 19 inches of water.
Normals 1991–2020 and records since 1996 at Elizabeth 2 NW, 17 miles northeast. NOAA, through RCC-ACIS.
