The Spencer 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; warmer
Mostly sunny
Partly cloudy
Partly cloudy
Partly cloudy; cooler
Showers likely
Spencer’s center stands about 1,680 ft above sea level. Within three miles the land runs from 1,520 ft to 1,780 ft, a difference of 260 ft: rolling country. The highest named summit within 15 miles is Scalp Butte, about 1,890 ft, 14 miles north.
Under the town center the state geologic map shows Pierre Shale, from the Late Cretaceous, 66 to 100 million years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 33×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale. Age: Late Cretaceous, 66 to 100 million years old. About 17 mi of the line.
Siltstone-mudstone, conglomerate-sandstone. Age: Miocene, 5.3 to 23 million years old. About 5 mi of the line.
Shale, bentonite. Age: Late Cretaceous, 66 to 100 million years old. About 3 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 Spencer reaches the Gulf of America by way of Ponca Creek, the Missouri and the Mississippi: about 2,040 river miles.
Lake on the way: Lewis and Clark Lake.
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 Spencer; river miles along the main stem, rounded.
