The Armagh 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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77° on Nov. 11, 2020, the hottest reading for this week of the year since 1946. Next is 74° in 1956.
Armagh’s center stands about 1,550 ft above sea level. Within three miles the land runs from 1,100 ft to 1,890 ft, a difference of 790 ft: hilly country. The highest named summit within 15 miles is Irwin Hill, about 2,880 ft, 15 miles south.
Under the town center the state geologic map shows Glenshaw Formation (shale), from the Carboniferous, 299 to 324 million years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 12×. 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. Age: Carboniferous, 299 to 324 million years old. About 10 mi of the line.
Sandstone. Age: Carboniferous, 299 to 324 million years old. About 7 mi of the line.
Sandstone. Age: Carboniferous, 324 to 359 million years old. About 3 mi of the line.
Sandstone, conglomerate. Age: Carboniferous, 299 to 324 million years old. About 2 mi of the line.
Shale, clastic. Age: Carboniferous, 299 to 324 million years old. About 2 mi of the line.
Shale, siltstone, sandstone. Age: Carboniferous, 324 to 359 million years old. About 0.9 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 1 smaller unit along the line are not listed.
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 Armagh reaches the Gulf of America by way of Blacklick Creek, the Conemaugh, the Kiskiminetas, the Allegheny, the Ohio and the Mississippi: about 2,040 river miles.
970 miles of the trip are on the Ohio.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Armagh; river miles along the main stem, rounded.
Armagh has a warm-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 18° in January. A normal year brings about 46 inches of snow; with the rain, that comes to about 48 inches of water.
On November 14 Armagh normally reaches 52° and falls to 30°. The record high is 73°, in 1994; the record low 11°, in 1986. The most rain on this date, 0.77 in, fell in 1997.
Normals 1991–2020 and records since 1946 at Indiana 3 SE, 11 miles north-northwest, 450 ft lower. NOAA, through RCC-ACIS.
