The Keystone 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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27° on Nov. 17, 1940, the coldest reading for this week of the year since 1892. Next is 32° in 1901.
Keystone’s center stands about 50 ft above sea level. Within three miles the land runs from 30 ft to 90 ft, a difference of 60 ft: gently rolling country.
Under the town center the state geologic map shows Undifferentiated sediments (sand, clay), from the Pleistocene to Holocene, less than 2.6 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.
Sand, clay. Age: Pleistocene to Holocene, less than 2.6 million years old. About 18 mi of the line.
Sand, clay. Age: Pleistocene to Holocene, less than 2.6 million years old. About 2 mi of the line.
Limestone. Age: Late Oligocene to Middle Miocene, 12 to 28 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.
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 Keystone reaches Tampa Bay and the Gulf of America by way of Tarpon, Lake: about 13 river miles.
Lake on the way: Tarpon, Lake.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Keystone; river miles along the main stem, rounded.
Keystone has a humid subtropical climate. Summer afternoons average 91° in July; winter nights fall to about 51° in January. About 54 inches of rain fall in a normal year.
On November 14 Keystone normally reaches 76° and falls to 59°. The record high is 89°, in 1955; the record low 34°, in 1932. The most rain on this date, 3.50 in, fell in 1916.
Normals 1991–2020 and records since 1892 at Tarpon Spgs Sewage Pl, 8 miles west. NOAA, through RCC-ACIS.
