The Marshalltown 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.
Sunny
Partly cloudy; warmer
Mostly sunny
Mostly sunny
Partly cloudy
Mostly sunny
Showers likely
80° on Nov. 14, 1999, the hottest reading for this week of the year since 1893. Next is 77° in 1941.
Marshalltown’s center stands about 940 ft above sea level. Within three miles the land runs from 850 ft to 1,010 ft, a difference of 160 ft: gently rolling country.
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.
Dolostone, limestone, siltstone. Age: Early Mississippian, 347 to 359 million years old. About 12 mi of the line.
Dolostone, limestone. Age: Early Mississippian to Middle Mississippian, 331 to 359 million years old. About 6 mi of the line.
Shale, sandstone, siltstone. Age: Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 million years old. About 3 mi of the line.
Limestone. Age: Early Mississippian to Middle Mississippian, 331 to 359 million years old. About 2 mi of the line.
Shale, limestone, dolostone. Age: Late Devonian, 374 to 384 million years old. About 0.5 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 Marshalltown reaches the Gulf of America by way of Anson Creek, Linn Creek, the Iowa and the Mississippi: about 1,610 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Marshalltown; river miles along the main stem, rounded.
Marshalltown has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 9° in January. A normal year brings about 25 inches of snow; with the rain, that comes to about 38 inches of water.
On November 14 Marshalltown normally reaches 47° and falls to 27°. The record high is 80°, in 1999; the record low −1°, in 1916. The most rain on this date, 1.36 in, fell in 1902.
Normals 1991–2020 and records since 1893 at Marshalltown, here. NOAA, through RCC-ACIS.
