The Johnston 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.
Partly cloudy
Mostly sunny; warmer
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78° on Nov. 15, 1993, the hottest reading for this week of the year since 1904. Next is 75° in 1909.
Johnston’s center stands about 280 ft above sea level. Within three miles the land runs from 80 ft to 530 ft, a difference of 450 ft: hilly country. The highest named summit within 15 miles is Jerimoth Hill, about 860 ft, 13 miles west.
Under the town center the state geologic map shows Scituate Igneous Suite - alkali-feldspar granite (alkali-feldspar-granite), from the Late Devonian, 366 to 380 million years old.
The section below crosses 8 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.
Age: Carboniferous, 299 to 324 million years old. About 5 mi of the line.
Alkali-feldspar-granite. Age: Late Devonian, 366 to 380 million years old. About 4 mi of the line.
Granite. Age: Neoproterozoic, 613 to 629 million years old. About 3 mi of the line.
Gneiss. Age: Neoproterozoic, 542 to 1,000 million years old. About 3 mi of the line.
Metasedimentary. Age: Neoproterozoic to Carboniferous, 299 to 1,000 million years old. About 3 mi of the line.
Granite. Age: Late Devonian, 366 to 380 million years old. About 2 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 2 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 Johnston reaches Narragansett Bay and the Atlantic Ocean by way of the Pocasset, the Pawtuxet and the Providence: about 16 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Johnston; river miles along the main stem, rounded.
Johnston has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 22° in January. A normal year brings about 37 inches of snow; with the rain, that comes to about 48 inches of water.
On November 14 Johnston normally reaches 54° and falls to 36°. The record high is 75°, in 1993; the record low 16°, in 1905. The most rain on this date, 2.13 in, fell in 2009.
Normals 1991–2020 and records since 1904 from the Providence Area threaded record (Rhode Island T.F. Green International Airport, 9 miles south-southeast, 230 ft lower). NOAA, through RCC-ACIS.
