The La Harpe 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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79° on Nov. 11, 1964, the hottest reading for this week of the year since 1895. Next is 78° in 1896.
La Harpe’s center stands about 700 ft above sea level. Within three miles the land runs from 610 ft to 740 ft, a difference of 130 ft: gently rolling country.
Under the town center the state geologic map shows Meppen Limestone, Fern Glen Formation, and Burlington-Keokuk Limestone, from the Early Mississippian to Middle Mississippian, 331 to 359 million years old.
The section below crosses 5 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.
Limestone. Age: Early Mississippian to Middle Mississippian, 331 to 359 million years old. About 12 mi of the line.
Shale, sandstone, coal. Age: Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old. About 8 mi of the line.
Limestone. Age: Middle Mississippian, 331 to 347 million years old. About 2 mi of the line.
Shale, sandstone. Age: Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 million years old. About 1 mi of the line.
Dolostone, limestone. Age: Early Mississippian to Middle Mississippian, 331 to 359 million years old. About 1 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 La Harpe reaches the Gulf of America by way of the South Branch La Moine, the La Moine, the Illinois and the Mississippi: about 1,380 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of La Harpe; river miles along the main stem, rounded.
La Harpe has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 15° in January. About 39 inches of rain fall in a normal year.
On November 14 La Harpe normally reaches 50° and falls to 31°. The record high is 77°, in 1989; the record low 5°, in 1940. The most rain on this date, 1.15 in, fell in 1926.
Normals 1991–2020 and records since 1895 at La Harpe, here. NOAA, through RCC-ACIS.
