The Hamilton 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
Partly cloudy
3° on Nov. 17, 1959, the coldest reading for this week of the year since 1891. Next is 5° in 1940.
Hamilton’s center stands about 660 ft above sea level. Within three miles the land runs from 490 ft to 670 ft, a difference of 180 ft: gently rolling country.
Under the town center the state geologic map shows Warsaw Formation and Salem Limestone, from the Middle Mississippian, 331 to 347 million years old.
The section below crosses 4 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: Middle Mississippian, 331 to 347 million years old. About 11 mi of the line.
Limestone. Age: Middle Mississippian, 331 to 347 million years old. About 10 mi of the line.
Limestone. Age: Early Mississippian to Middle Mississippian, 331 to 359 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.
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 Hamilton reaches the Gulf of America by way of Railroad Creek and the Mississippi: about 1,340 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Hamilton; river miles along the main stem, rounded.
Hamilton has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 17° in January. About 40 inches of rain fall in a normal year.
On November 14 Hamilton normally reaches 51° and falls to 33°. The record high is 78°, in 1999; the record low 7°, in 1940. The most rain on this date, 1.32 in, fell in 1926.
Normals 1991–2020 and records since 1891 at Keokuk L&D 19, here, 140 ft lower. NOAA, through RCC-ACIS.
