The Green Mountain 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
−7° on Nov. 12, 2019, the coldest reading for this week of the year since 1996. Next is 2° in 2005.
Green Mountain’s center stands about 990 ft above sea level. Within three miles the land runs from 890 ft to 1,030 ft, a difference of 140 ft: gently rolling country.
The section below crosses 6 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 9 mi of the line.
Shale, siltstone. Age: Late Devonian, 359 to 374 million years old. About 6 mi of the line.
Dolostone, limestone. Age: Early Mississippian to Middle Mississippian, 331 to 359 million years old. About 3 mi of the line.
Limestone. Age: Early Mississippian to Middle Mississippian, 331 to 359 million years old. About 3 mi of the line.
Shale, limestone, dolostone. Age: Late Devonian, 374 to 384 million years old. About 2 mi of the line.
Shale, sandstone, siltstone. Age: Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 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 Green Mountain reaches the Gulf of America by way of Nickolson 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 Green Mountain; river miles along the main stem, rounded.
Green Mountain has a dry-winter hot-summer continental climate. Summer afternoons average 83° in July; winter nights fall to about 10° in January. About 33 inches of rain fall in a normal year.
On November 14 Green Mountain normally reaches 47° and falls to 27°. The record high is 72°, in 2025; the record low 8°, in 2019.
Normals 1991–2020 and records since 1996 at Marshalltown Municipal Airport, 5 miles west. NOAA, through RCC-ACIS.
