The Old Saybrook 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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Old Saybrook’s center stands about 30 ft above sea level. Within three miles the land runs from 0 ft to 220 ft, a difference of 220 ft: rolling country. Open water lies within three miles. The highest named summit within 15 miles is Goose Hill, about 700 ft, 14 miles northwest.
Under the town center the state geologic map shows Brimfield Schist (Includes Hamilton Resevoir Formation) (schist, gneiss), from the Cambrian to Ordovician, 445 to 542 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 34×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Amphibolite, hornblende-gneiss. Age: Middle Ordovician, 459 to 471 million years old. About 4 mi of the line.
Gneiss, granofels. Age: Middle Ordovician, 459 to 471 million years old. About 3 mi of the line.
Gneiss, amphibolite. Age: Early Ordovician to Middle Ordovician, 459 to 487 million years old. About 3 mi of the line.
About 2 mi of the line.
Schist, gneiss. Age: Cambrian to Ordovician, 445 to 542 million years old. About 1 mi of the line.
Gneiss, schist. Age: Neoproterozoic, 542 to 1,000 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. 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 Old Saybrook reaches Long Island Sound and the Atlantic Ocean by way of the Oyster and the Back: about 1 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Old Saybrook; river miles along the main stem, rounded.
