The Bolan 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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74° on Nov. 14, 1999, the hottest reading for this week of the year since 1896. Next is 71° in 1939.
Bolan’s center stands about 1,220 ft above sea level. Within three miles the land runs from 1,170 ft to 1,230 ft, a difference of 60 ft: gently rolling country.
Under the town center the state geologic map shows Cedar Valley Group (limestone, dolostone), from the Middle Devonian to Late Devonian, 374 to 388 million years old.
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.
Limestone, dolostone. Age: Middle Devonian to Late Devonian, 374 to 388 million years old. About 24 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 Bolan reaches the Gulf of America by way of the Shell Rock, the Cedar River, the Iowa and the Mississippi: about 1,700 river miles.
1,410 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Bolan; river miles along the main stem, rounded.
Bolan has a warm-summer humid continental climate. Summer afternoons average 79° in July; winter nights fall to about 4° in January. A normal year brings about 40 inches of snow; with the rain, that comes to about 36 inches of water.
On November 14 Bolan normally reaches 41° and falls to 23°. The record high is 74°, in 1999; the record low −6°, in 1959. The most rain on this date, 1.24 in, fell in 1902.
Normals 1991–2020 and records since 1896 at Northwood, 7 miles northwest. NOAA, through RCC-ACIS.
