The Allegany 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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74° on Nov. 11, 2020, the hottest reading for this week of the year since 1956. Next is 69° in 2012.
Allegany’s center stands about 2,280 ft above sea level. Within three miles the land runs from 1,900 ft to 2,560 ft, a difference of 660 ft: hilly country. The highest named summit within 15 miles is Bailey Hill, about 2,590 ft, 10 miles east.
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 19×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone, siltstone, shale. Age: Late Devonian, 359 to 384 million years old. About 13 mi of the line.
Sandstone, siltstone. Age: Devonian to Carboniferous, 324 to 422 million years old. About 8 mi of the line.
Sandstone, conglomerate. Age: Carboniferous, 299 to 324 million years old. About 2 mi of the line.
Siltstone, shale. Age: Late Devonian, 359 to 384 million years old. About 1 mi of the line.
Sandstone, siltstone, mudstone. Age: Late Devonian, 359 to 384 million years old. About 0.4 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.
Allegany straddles the St. Lawrence Divide. Rain on the northeast side runs to Lake Ontario; most of the rest goes to the Gulf of America.
From the center of town, a raindrop reaches the Gulf of America by way of Dwight Creek, the Allegheny, the Ohio and the Mississippi: about 2,270 river miles. One that lands on the northeast side reaches Lake Ontario by way of the West Branch Genesee and the Genesee: about 160 river miles. From the lake it goes down the St. Lawrence to the Atlantic.
Lake on the way: Allegheny Reservoir.
970 miles of the trip are on the Ohio.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Allegany; river miles along the main stem, rounded.
Allegany has a warm-summer humid continental climate. Summer afternoons average 79° in July; winter nights fall to about 13° in January. A normal year brings about 54 inches of snow; with the rain, that comes to about 40 inches of water.
Normals 1991–2020 and records since 1956 at Wellsville, 17 miles north, 770 ft lower. NOAA, through RCC-ACIS.
