The Rock Island 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.
Mostly cloudy
Showers likely
Chance of showers; cooler
Mostly sunny
Mostly cloudy; warmer
Partly cloudy
Partly cloudy
7.20 inches of rain fell in two days, the most for this week of the year since records began in 1903. The next wettest, 5.33 inches, fell in 2007.
Rock Island’s center stands about 250 ft above sea level. Within three miles the land runs from 210 ft to 300 ft, a difference of 90 ft: gently rolling country.
Under the town center the state geologic map shows Lissie Formation (silt, sand, clay), from the Pleistocene, less than 2.6 million years old.
The section below crosses 2 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.
Silt, sand, clay. Age: Pleistocene, less than 2.6 million years old. About 14 mi of the line.
Coarse-detrital, fine-detrital. Age: Pliocene, 2.6 to 5.3 million years old. About 10 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 Rock Island reaches the Gulf of America by way of Pinoak Creek, Sandy Creek, the Navidad and the Lavaca: about 85 river miles.
Often dry. About 50% of the way is mapped as streams that run only after rain or snowmelt; the water makes the whole trip in floods.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Rock Island; river miles along the main stem, rounded.
Rock Island has a humid subtropical climate. Summer afternoons average 98° in August; winter nights fall to about 38° in January. About 45 inches of rain fall in a normal year.
On November 14 Rock Island normally reaches 74° and falls to 48°. The record high is 89°, in 2007; the record low 26°, in 2018. The most rain on this date, 1.54 in, fell in 1961.
Normals 1991–2020 and records since 1903 at Columbus, 12 miles north. NOAA, through RCC-ACIS.
