The Jamestown 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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Jamestown’s center stands about 6,940 ft above sea level. Within three miles the land runs from 6,830 ft to 7,460 ft, a difference of 630 ft: hilly country. The highest named summit within 15 miles is Mount Powell, about 8,730 ft, 11 miles east.
The section below crosses 12 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 12×. 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: Middle Triassic to Late Triassic, 202 to 247 million years old. About 7 mi of the line.
Unconsolidated. Age: Pleistocene to Holocene, less than 0.1 million years old. About 3 mi of the line.
Shale, limestone. Age: Late Cretaceous, 90 to 100 million years old. About 3 mi of the line.
Sandstone. Age: Permian, 273 to 290 million years old. About 2 mi of the line.
Sandstone, siltstone. Age: Middle Jurassic, 164 to 175 million years old. About 2 mi of the line.
Sandstone, shale. Age: Late Jurassic, 145 to 164 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. 6 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 Jamestown reaches the Gulf of California by way of the South Fork Puerco, the Puerco, the Little Colorado and the Colorado: about 1,090 river miles.
Lakes on the way: Lake Mead, Lake Mohave and Lake Havasu.
290 miles of the trip are on the Colorado.
Often dry. About 30% of the way is mapped as streams that run only after rain or snowmelt; the water makes the whole trip in floods.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Jamestown; river miles along the main stem, rounded.
