The Rockdale 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 sunny
Mostly sunny; warmer
Mostly sunny
Sunny
Partly cloudy
Mostly sunny
Partly cloudy
74° on Nov. 14, 1989, the hottest reading for this week of the year since 1943. Next is 74° in 2020.
Rockdale’s center stands about 560 ft above sea level. Within three miles the land runs from 500 ft to 670 ft, a difference of 170 ft: gently rolling country.
Under the town center the state geologic map shows Silurian System undivided (dolostone, limestone), from the Silurian, 422 to 445 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 61×. 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. Age: Silurian, 422 to 445 million years old. About 18 mi of the line.
Shale, limestone. Age: Late Ordovician, 445 to 454 million years old. About 6 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 Rockdale reaches the Gulf of America by way of the Des Plaines, the Illinois and the Mississippi: about 1,480 river miles.
Lake on the way: Peoria Lake.
1,190 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Rockdale; river miles along the main stem, rounded.
Rockdale has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 17° in January. A normal year brings about 17 inches of snow; with the rain, that comes to about 38 inches of water.
On November 14 Rockdale normally reaches 49° and falls to 33°. The record high is 74°, in 1989; the record low 6°, in 1986. The most rain on this date, 1.50 in, fell in 1972.
Normals 1991–2020 and records since 1943 at Joliet Brandon Road Lock/Dam, here. NOAA, through RCC-ACIS.
