The St. Mary's 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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60° on Nov. 13, 1999, the hottest reading for this week of the year since 1968. Next is 58° in 1980.
St. Mary's’s center stands about 10,080 ft above sea level. Within three miles the land runs from 8,920 ft to 12,380 ft, a difference of 3,460 ft: mountain country. The highest named summit within 15 miles is Mount Spalding, about 13,830 ft, 15 miles south.
Under the town center the state geologic map shows Glacial drift (unconsolidated), from the Pleistocene, less than 0.5 million years old.
The section below crosses 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 3×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Biotite-gneiss, schist, migmatite. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 11 mi of the line.
Gneiss. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 4 mi of the line.
Unconsolidated. Age: Pleistocene, less than 0.5 million years old. About 4 mi of the line.
Alkali-feldspar-granite, granite. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 2 mi of the line.
Gravel. Age: Miocene to Pliocene, 2.6 to 23 million years old. About 2 mi of the line.
Granitic, dioritic. Age: Late Cretaceous to Middle Eocene, 40 to 72 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.
A raindrop that lands in St. Mary's reaches the Gulf of America by way of Silver Creek, the Fall, Clear Creek, the South Platte, the Platte, the Missouri and the Mississippi: about 2,440 river miles.
1,170 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of St. Mary's; river miles along the main stem, rounded.
St. Mary's has a subarctic climate. Summer afternoons average 69° in July; winter nights fall to about 12° in January. A normal year brings about 154 inches of snow; with the rain, that comes to about 22 inches of water.
On November 14 St. Mary's normally reaches 40° and falls to 19°. The record high is 58°, in 1990; the record low −8°, in 1997. The most rain on this date, 0.39 in, fell in 1983.
Normals 1991–2020 and records since 1968 at Cabin Creek, 12 miles south-southwest. NOAA, through RCC-ACIS.
