The Marshan 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.
Mostly sunny
Mostly sunny; warmer
Partly cloudy
Partly cloudy
Partly cloudy
Partly cloudy
Showers likely
73° on Nov. 15, 2025, the hottest reading for this week of the year since 1893. Next is 72° in 1990.
Marshan’s center stands about 870 ft above sea level. Within three miles the land runs from 810 ft to 960 ft, a difference of 150 ft: gently rolling country. The highest named summit within 15 miles is Negro Hill, about 1,130 ft, 13 miles east-northeast.
Under the town center the state geologic map shows Lower Ordovician (dolostone, sandstone), from the Early Ordovician, 471 to 487 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 46×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Dolostone, sandstone. Age: Early Ordovician, 471 to 487 million years old. About 10 mi of the line.
Shale, limestone, sandstone. Age: Middle Ordovician to Late Ordovician, 445 to 471 million years old. About 5 mi of the line.
Sandstone, siltstone, shale. Age: Cambrian, 487 to 497 million years old. About 3 mi of the line.
Dolostone. Age: Early Ordovician, 471 to 487 million years old. About 3 mi of the line.
Sandstone. Age: Ordovician, 445 to 487 million years old. About 2 mi of the line.
Dolostone. Age: Ordovician, 445 to 487 million years old. About 0.6 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 Marshan reaches the Gulf of America by way of the Vermillion, Vermillion Slough and the Mississippi: about 1,800 river miles.
Lake on the way: Lake Pepin.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Marshan; river miles along the main stem, rounded.
Marshan has a hot-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 6° in January. About 33 inches of rain fall in a normal year.
On November 14 Marshan normally reaches 44° and falls to 27°. The record high is 72°, in 1990; the record low 7°, in 1940. The most rain on this date, 1.24 in, fell in 1951.
Normals 1991–2020 and records since 1893 at Hastings Dam 2, 7 miles north, 190 ft lower. NOAA, through RCC-ACIS.
