The Portia 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.
Sunny
Partly cloudy; warmer
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83° on Nov. 15, 1964, the hottest reading for this week of the year since 1905. Next is 82° in 1989.
Portia’s center stands about 260 ft above sea level. Within three miles the land runs from 240 ft to 360 ft, a difference of 120 ft: gently rolling country. The highest named summit within 15 miles is Cave Hill, about 730 ft, 15 miles west-northwest.
Under the town center the state geologic map shows Dune sand, from the Pleistocene, less than 2.6 million years old.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 49×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone, dolostone. Age: Middle Ordovician, 459 to 471 million years old. About 9 mi of the line.
Coarse-detrital, fine-detrital. Age: Pleistocene, less than 2.6 million years old. About 8 mi of the line.
Sand. Age: Pleistocene, less than 2.6 million years old. About 5 mi of the line.
Coarse-detrital, fine-detrital. Age: Holocene, less than 12,000 years old. About 1 mi of the line.
Dolostone. Age: Early Ordovician, 471 to 487 million years old. About 0.8 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 Portia reaches the Gulf of America by way of the Black River, the White River and the Mississippi: about 950 river miles.
620 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Portia; river miles along the main stem, rounded.
Portia has a humid subtropical climate. Summer afternoons average 88° in July; winter nights fall to about 28° in January. About 48 inches of rain fall in a normal year, with about 4 inches of snow.
On November 14 Portia normally reaches 58° and falls to 39°. The record high is 81°, in 1964; the record low 18°, in 2019. The most rain on this date, 3.48 in, fell in 1957.
Normals 1991–2020 and records since 1905 at Alicia 2 NNE, 11 miles south. NOAA, through RCC-ACIS.
