The Lake Mary Ronan 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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68° on Nov. 12, 1999, the hottest reading for this week of the year since 1938. Next is 64° in 1990.
Lake Mary Ronan’s center stands about 3,740 ft above sea level. Within three miles the land runs from 3,470 ft to 5,570 ft, a difference of 2,100 ft: mountain country. The highest named summit within 15 miles is Blacktail Mountain, about 6,750 ft, 5 miles north-northeast.
The section below crosses 2 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 6×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Quartzite, argillite, metasiltstone. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 13 mi of the line.
Unconsolidated. Age: Pleistocene to Holocene, less than 1.8 million years old. About 8 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 Lake Mary Ronan reaches the Pacific Ocean by way of Ronan Creek, Dayton Creek, the Flathead, the Clark Fork, the Pend Oreille and the Columbia: about 1,070 river miles.
Lakes on the way: Flathead Lake, Lake Pend Oreille, Lake Umatilla and Noxon Rapids Reservoir.
460 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Lake Mary Ronan; river miles along the main stem, rounded.
Lake Mary Ronan has a warm-summer humid continental climate. Summer afternoons average 80° in July; winter nights fall to about 25° in January. About 21 inches of rain fall in a normal year.
On November 14 Lake Mary Ronan normally reaches 42° and falls to 32°. The record high is 65°, in 1999; the record low 0°, in 1955. The most rain on this date, 0.43 in, fell in 2005.
Normals 1991–2020 and records since 1938 at Bigfork 13 S, 17 miles east-southeast, 760 ft lower. NOAA, through RCC-ACIS.
