The Croghan 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 1891. Next is 69° in 1964.
Croghan’s center stands about 840 ft above sea level. Within three miles the land runs from 760 ft to 1,010 ft, a difference of 250 ft: rolling country. The highest named summit within 15 miles is Bald Mountain, about 1,660 ft, 13 miles northeast.
Under the town center the state geologic map shows Biotite and/or hornblende granite gneiss, from the Mesoproterozoic, 1 to 1.6 billion years old.
The section below crosses 12 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 21×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Unconsolidated. Age: Quaternary, less than 2.6 million years old. About 9 mi of the line.
Gneiss. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 4 mi of the line.
Limestone. Age: Middle Ordovician, 459 to 471 million years old. About 3 mi of the line.
Gneiss. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 2 mi of the line.
Hornblende-gneiss. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 1 mi of the line.
Metasedimentary, migmatite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 6 smaller units 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 Croghan reaches the St. Lawrence River by way of the Indian, the Oswegatchie and the Saint Lawrence: about 170 river miles. The St. Lawrence carries it on to the Atlantic.
Lakes on the way: Lake Saint Lawrence and Black Lake.
90 miles of the trip are on the Indian.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Croghan; river miles along the main stem, rounded.
Croghan has a warm-summer humid continental climate. Summer afternoons average 78° in July; winter nights fall to about 8° in January. A normal year brings about 127 inches of snow; with the rain, that comes to about 42 inches of water.
On November 14 Croghan normally reaches 45° and falls to 28°. The record high is 65°, in 1930; the record low 1°, in 2019. The most rain on this date, 1.06 in, fell in 1925.
Normals 1991–2020 and records since 1891 at Lowville, 8 miles south-southwest. NOAA, through RCC-ACIS.
