The Rock Lake 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
Mostly sunny
Partly cloudy
Partly cloudy
Partly cloudy
Showers likely
79° on Nov. 14, 1999, the hottest reading for this week of the year since 1887. Next is 74° in 1953.
Rock Lake’s center stands about 1,550 ft above sea level. Within three miles the land runs from 1,480 ft to 1,640 ft, a difference of 160 ft: gently rolling country. The highest named summit within 15 miles is Stony Point, about 1,970 ft, 14 miles southwest.
Under the town center the state geologic map shows Undifferentiated (conglomerate, sandstone, mudstone), from the Late Cretaceous, 72 to 100 million years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 35×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Conglomerate, sandstone, mudstone. Age: Late Cretaceous, 72 to 100 million years old. About 14 mi of the line.
Quartzite, mudstone. Age: Paleoproterozoic, 1.6 to 2 billion years old. About 7 mi of the line.
Orthogneiss. Age: Paleoarchean to Mesoarchean, 2.8 to 3.6 billion years old. About 2 mi of the line.
Age: Paleoproterozoic, 1.8 to 2 billion years old. About 1.0 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 Rock Lake reaches the Gulf of America by way of the Cottonwood, the Minnesota and the Mississippi: about 2,100 river miles.
Lake on the way: Lake Pepin.
1,750 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Rock Lake; river miles along the main stem, rounded.
Rock Lake has a hot-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 5° in January. A normal year brings about 49 inches of snow; with the rain, that comes to about 29 inches of water.
On November 14 Rock Lake normally reaches 42° and falls to 25°. The record high is 79°, in 1999; the record low −10°, in 1959. The most rain on this date, 0.38 in, fell in 1983.
Normals 1991–2020 and records since 1887 at Tracy, 13 miles east, 150 ft lower. NOAA, through RCC-ACIS.
