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  September 25, 2000

Earthly Matters:
The Ups and Downs of Avery Point

The eastern Connecticut shoreline has a salty, icy, rocky history. This indented coast of granite headlands, sandy beaches and marshy estuaries provided shelter, food, and freshwater for Native American villages, as well as for early colonial European explorers.

Protected from Atlantic gales by Long Island, the placid inner coast later became a playground for wealthy industrialists, who built their mansion-sized summer homes along its shore. One of these so-called cottages, the Branford House in Groton, became the nucleus for UConn's Avery Point campus, home to the Marine Sciences &Technology Center, now a world-class oceanographic institution.

Although standing well above sea level, the land beneath Avery Point has had its ups and downs, as well as its hot and cold stages. The rock beneath the point originated far below the surface, deep within the crust, at hellish temperatures and pressures.

Over the eons, however, this metamorphic rock rose upward more than a dozen miles, cooling, hardening, and cracking in the process. Then powerful waves of the early Atlantic Ocean washed over the region, transforming this once-mountainous topography into a broad lowland mantled by a sandy coastal plain.

Sea level was particularly high 75-65 million years ago, during the demise of the dinosaurs. At that time, the eastern Connecticut shore extended from Plainfield to Franklin to Colchester to Deep River; meanwhile, Avery Point was submerged beneath a sparking blue sea.

Then global sea levels fell. Erosion stripped away the soft strata of the coastal plain, exposing the beveled-off hard rock surface below. Avery Point had gone up, then down, then up once again.

Then came the age of ice. On several occasions, a vast ice sheet originating in central Canada invaded southward, then retreated northward as the climate changed. Each pulse of glaciation from this Laurentide Ice Sheet weighted down the land, flexing the Connecticut coastline first up, then down as the ice drew near. Each pulse also caused global sea level to fall (as seawater was withdrawn to make glacier ice), then to rise, as melt water returned to the sea. With respect to sea level, Avery Point had gone up, then down.

The sinking process continues today. The upward bulge in the crust at Avery Point continues to collapse at approximately a half-millimeter every year. Simultaneously, the surface of our interglacial sea continues to rise, as glacier water returns to the sea and is warmed. Like Venice, parts of Avery Point disappear each year. And if our climate continues to warm, as it has been doing for more than a century, vast amounts of water now stored in the Greenland and Antarctica Ice Sheets may melt back into the global ocean, raising sea level perhaps as much as 15-20 feet above its present level, possibly within the next half-millennium.

There is no need for immediate alarm. UConn's shoreline campus will continue to stand above salt water for at least several centuries. But ultimately, Connecticut's eastern shore will go under, once again.

Robert M. Thorson