The Royal Lakes 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.
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3.25 inches of rain fell in two days, the most for this week of the year since records began in 1892. The next wettest, 2.92 inches, fell in 2003.
Royal Lakes’s center stands about 650 ft above sea level. Within three miles the land runs from 610 ft to 670 ft, a difference of 60 ft: gently rolling country.
Under the town center the state geologic map shows Shelburn-Patoka Formations undivided (shale, limestone), from the Late Pennsylvanian, 304 to 307 million years old.
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.
Shale, limestone. Age: Late Pennsylvanian, 304 to 307 million years old. About 24 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 Royal Lakes reaches the Gulf of America by way of Coop Branch, Macoupin Creek, the Illinois and the Mississippi: about 1,270 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Royal Lakes; river miles along the main stem, rounded.
Royal Lakes has a hot-summer humid continental climate. Summer afternoons average 87° in July; winter nights fall to about 22° in January. About 42 inches of rain fall in a normal year.
On November 14 Royal Lakes normally reaches 55° and falls to 37°. The record high is 77°, in 1999; the record low 11°, in 1986. The most rain on this date, 1.56 in, fell in 1993.
Normals 1991–2020 and records since 1892 at Alton - Melvin Price L&D, 20 miles south-southwest, 240 ft lower. NOAA, through RCC-ACIS.
