The Delta 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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−8° on Nov. 17, 1959, the coldest reading for this week of the year since 1893. Next is −7° in 1956.
Delta’s center stands about 1,050 ft above sea level. Within three miles the land runs from 950 ft to 1,290 ft, a difference of 340 ft: rolling country.
Under the town center the state geologic map shows Oronto Group; Freda Sandstone (arkose, siltstone), from the Mesoproterozoic, 1 to 1.6 billion years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 33×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Arkose, siltstone. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 22 mi of the line.
Siltstone, shale. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 2 mi of the line.
Sandstone, conglomerate. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 0.5 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 Delta reaches Lake Superior by way of the South Fork White, the White River and the Bad River: about 70 river miles. From there it moves on through the Great Lakes, over Niagara Falls and down the St. Lawrence to the Atlantic.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Delta; river miles along the main stem, rounded.
Delta has a warm-summer humid continental climate. Summer afternoons average 79° in July; winter nights fall to about 6° in January. About 28 inches of rain fall in a normal year.
On November 14 Delta normally reaches 41° and falls to 25°. The record high is 64°, in 1990; the record low −2°, in 1940. The most rain on this date, 0.88 in, fell in 1951.
Normals 1991–2020 and records since 1893 from the Ashland Area threaded record (Ashland Kennedy Memorial Airport, 18 miles east-northeast, 230 ft lower). NOAA, through RCC-ACIS.
