The Riga 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. 13, 2019, the coldest reading for this week of the year since 1871. Next is 9° in 1933.
Riga’s center stands about 700 ft above sea level. Within three miles the land runs from 680 ft to 710 ft, a difference of 30 ft: nearly flat ground.
Under the town center the state geologic map shows Antrim Shale (black-shale), from the Late Devonian, 359 to 384 million years old.
The section below crosses 9 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale. Age: Carboniferous, 324 to 359 million years old. About 8 mi of the line.
Dolostone. Age: Silurian, 422 to 428 million years old. About 7 mi of the line.
Black-shale. Age: Late Devonian, 359 to 384 million years old. About 3 mi of the line.
Shale. Age: Late Devonian, 359 to 384 million years old. About 2 mi of the line.
Dolostone. Age: Middle Devonian, 384 to 394 million years old. About 1 mi of the line.
Limestone. Age: Middle Devonian, 384 to 394 million years old. About 1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 3 smaller units along the line are not listed.
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 Riga reaches Lake Erie by way of the River Raisin: about 60 river miles. From there it moves on through the Great Lakes, over Niagara Falls and down the St. Lawrence to the Atlantic.
Often dry. About 30% of the way is mapped as streams that run only after rain or snowmelt; the water makes the whole trip in floods.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Riga; river miles along the main stem, rounded.
Riga has a hot-summer humid continental climate. Summer afternoons average 87° in July; winter nights fall to about 20° in January. A normal year brings about 37 inches of snow; with the rain, that comes to about 35 inches of water.
On November 14 Riga normally reaches 52° and falls to 35°. The record high is 72°, in 1909; the record low 11°, in 1986. The most rain on this date, 1.42 in, fell in 1879.
Normals 1991–2020 and records since 1871 from the Toledo Area threaded record (Toledo Express Airport, 15 miles south). NOAA, through RCC-ACIS.
