The Allport 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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Allport’s center stands about 200 ft above sea level. Within three miles the land runs from 190 ft to 240 ft, a difference of 50 ft: nearly flat ground.
Under the town center the state geologic map shows Alluvium - Alluvial deposits in major stream channels or in mappable meanders of major streams (coarse-detrital, fine-detrital), from the Holocene, less than 12,000 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 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Coarse-detrital, fine-detrital. Age: Holocene, less than 12,000 years old. About 18 mi of the line.
Coarse-detrital, fine-detrital. Age: Pleistocene, less than 2.6 million years old. About 4 mi of the line.
Coarse-detrital, fine-detrital. Age: Holocene, less than 12,000 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 Allport reaches the Gulf of America by way of the Bayou Meto, the Arkansas and the Mississippi: about 750 river miles.
600 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Allport; river miles along the main stem, rounded.
