The Portland 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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74° on Nov. 11, 1999, the hottest reading for this week of the year since 1948. Next is 73° in 2010.
Portland’s center stands about 920 ft above sea level. Within three miles the land runs from 890 ft to 980 ft, a difference of 90 ft: gently rolling country.
Under the town center the state geologic map shows Louisville Limestone through Brassfield Limestone, from the Silurian, 422 to 445 million 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 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.
Limestone. Age: Silurian, 422 to 445 million years old. About 22 mi of the line.
Shale, limestone. Age: Ordovician, 445 to 487 million years old. About 2 mi of the line.
Dolostone, limestone. Age: Silurian, 422 to 445 million years old. About 0.3 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 Portland reaches the Gulf of America by way of the Salamonie, the Wabash, Big Bayou, the Wabash River Old Channel, the Old Channel Wabash, the Ohio and the Mississippi: about 1,550 river miles.
970 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Portland; river miles along the main stem, rounded.
Portland has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 17° in January. A normal year brings about 19 inches of snow; with the rain, that comes to about 40 inches of water.
On November 14 Portland normally reaches 51° and falls to 32°. The record high is 71°, in 1999; the record low 10°, in 1986. The most rain on this date, 2.20 in, fell in 1951.
Normals 1991–2020 and records since 1948 at Portland 1 SW, here. NOAA, through RCC-ACIS.
