written for The New York Times

WHEN it comes to geographical lessons, Connecticut has two that it doesn’t share with just anybody.

Tourists often visit Dinosaur State Park, a spot where fossilized dinosaur footprints are surrounded by an arena. And they know about the quiet, undulating ocean coast near Mystic, where the landscape resembles Maine. Some visitors even understand that the reason there is no harbor in Old Saybrook, at the mouth of the Connecticut River, is that the 450-mile-long river ends on a sandbar.

The small town of Deep River, in south-central Connecticut, holds one of the state’s secrets, whose history is known to geologists as the crunch.
A rock outcropping next to the town’s ball field marks the spot where two continents crashed together 250 million years ago. When the land masses began to pull apart again, a hunk of what might have become Africa remained clinging to North America. Deep River is one of the few places where the ”suture line” can be viewed.

For a long time, millions of years, in fact, the suture was not visible. Then, a few years ago, a Boy Scout troop and the Deep River Land Trust joined to dig a trench across the central part of the rock ledge, which is right along Route 154 at the entrance to Devitt Field. They removed several inches of dirt that had been deposited on top of most of the ridge during the last Ice Age about 18,000 years ago. When they were done, a band of rock lay exposed.

On the eastern side of the rock outcropping is land that was an island continent 500 million years ago. Geologists call it Avalonia and say it probably floated in a giant ocean south of what became North America and north of what became Africa. On the western side of the Deep River outcropping is the beginning of the rest of North America.

The meeting of Avalonia and North America, known as the Honey Hill Fault, runs in an arc from just west of the Deep River ball field, across the Connecticut River, northeast and then slightly southeast to the Ledyard area, and finally due north into Massachusetts.

All of the coastal towns from New Haven to Stonington are Avalonian land. About half of New London County is Avalonia. The entire Thames River, which flows from Norwich to New London, is within the Avalonian terrain.

About nine years ago, Janet Stone, a geologist for the United States Geological Survey in East Hartford and a resident of Deep River, got a call from Robert Wintsch, a geologist at Indiana University who had been hired to make a new map of the Deep River quadrangle.

”He said, ‘I think the Honey Hill fault is going right through Devitt Field,’ ” Ms. Stone recalled.

The geologists examined the rock and found that it changed in the middle of the outcropping. While the Honey Hill Fault was identified many years ago, the Devitt Field outcropping was a recent discovery of a visible location of the fault line.

Another one of the state’s secrets has to do with its highest elevation. The Connecticut high point lies beyond a clearing where hikers stop to sign a trail register.

A note in the register warns the hikers that they haven’t reached the high point yet. They still have a few tenths of a mile more.

Many people think that it is Bear Mountain, near Salisbury in the northwestern corner of the state. It is not. Bear Mountain, 2,316 feet above sea level, is only the highest mountain that lies entirely within the state.

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About This Article

This article first appeared in The New York Times on December 5, 1999. The editor, Jim Schembari, found a way to contain my interest in writing about two little-discussed and unrelated geographic points in Connecticut. He suggested combining them into one article. The spot marking the crash of two continents lies about seven-tenths of a mile from my house.

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