The Zap 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
Partly cloudy
Partly cloudy; cooler
Mostly cloudy; cooler
Partly cloudy
Chance of showers
Zap’s center stands about 1,840 ft above sea level. Within three miles the land runs from 1,810 ft to 2,140 ft, a difference of 330 ft: rolling country. The highest named summit within 15 miles is Medicine Butte, about 2,300 ft, 11 miles south.
Under the town center the state geologic map shows Sentinel Butte Formation (siltstone, claystone, sandstone), from the Paleocene, 56 to 66 million years old.
The section below crosses 2 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 40×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Siltstone, claystone, sandstone. Age: Paleocene, 56 to 66 million years old. About 22 mi of the line.
Sandstone, claystone, siltstone. Age: Paleocene to Eocene, 34 to 66 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 Zap reaches the Gulf of America by way of Spring Creek, the Knife, the Missouri and the Mississippi: about 2,590 river miles.
Lakes on the way: Lake Oahe, Lake Sharpe, Lake Francis Case and 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 Zap; river miles along the main stem, rounded.
