The Irondale 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° on Nov. 13, 2019, the coldest reading for this week of the year since 1893. Next is 8° in 1894.
Irondale’s center stands about 810 ft above sea level. Within three miles the land runs from 750 ft to 1,130 ft, a difference of 380 ft: rolling country. The highest named summit within 15 miles is Buford Mountain, about 1,760 ft, 9 miles south.
Under the town center the state geologic map shows Elvins Group - (including Derby-Doerun Dolomite, Davis Formation), Bonneterre Dolomite (dolostone, shale, siltstone), from the Cambrian, 487 to 497 million years old.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 22×. 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. Age: Cambrian, 487 to 497 million years old. About 10 mi of the line.
Dolostone, shale, siltstone. Age: Cambrian, 487 to 497 million years old. About 9 mi of the line.
Rhyolite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 3 mi of the line.
Sandstone. Age: Cambrian, 487 to 497 million years old. About 2 mi of the line.
Alkali-feldspar-granite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 0.6 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 Irondale reaches the Gulf of America by way of the Big River, the Meramec and the Mississippi: about 1,290 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Irondale; river miles along the main stem, rounded.
Irondale has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 21° in January. A normal year brings about 12 inches of snow; with the rain, that comes to about 46 inches of water.
On November 14 Irondale normally reaches 55° and falls to 36°. The record high is 76°, in 1993; the record low 10°, in 2019. The most rain on this date, 4.20 in, fell in 1993.
Normals 1991–2020 and records since 1893 at Potosi 4 SW, 10 miles west-northwest, 360 ft higher. NOAA, through RCC-ACIS.
