Connecticut Geology Trips

Selected excerpts from Great Day Trips to Discover the Geology of Connecticut, by Greg McHone, Ph.D.

Copyright © Perry Heights Press, 2004

This material may not be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage retrieval system, without written permission from the publisher Perry Heights Press.

Geology is about the deep past, but is itself a young science. Ideas about continental drift and plate tectonics that emerged in the past few decades advanced our knowledge of earth history—and how our region came to be as we see it today. Evidence for these modern concepts surrounds us in Connecticut.

Kent Falls State Park, Kent

A perfect place to picnic—and to explore the geology of the marble valleys of the northwest corner. An spectacular outcrop of the Stockbridge Marble is seen at Kent Falls.

Much of the bedrock of Connecticut was once seafloor beneath an ancient ocean known as Iapetus. As ancient continents slowly converged, Iapetus was closed, and the seafloor beneath it metamorphosed into local bedrock.

In places, marine shelled animals and corals made the muddy seafloor lime-rich. Metamorphism later converted these lime-rich muds into limestone and into marble, rocks like those found in the northwest hills and that have been eroded to form the beautiful waterfalls at the park.

Deep River and the Terrane of Avalonia

There aren't many places where you can see the seam where two pieces of the earth's continental crust actually collided—and few are more easily explore than the contact boundary seen in an outcrop of bedrock in Deep River.

Look carefully you can see two different sections of rock pressed against one another. On one side is a section of the Merrimack Terrane, and on the other a section of a former continent, Avalonia, that is today associated with Africa.

It's a place where you can stand astride the seam and imagine that you have one foot in an early area of North America, and the other on a section of crust destined to become a part of Africa.

Castle Craig, Meriden

It comes as a surprise to us today, but generations of geologists realized that there was volcanic activity in the Connecticut region in the past.

The question is, did the lava floods that built the traprock ridges and places like the Hanging Hills of Meriden extend beyond the Connecticut River Valley, and over a large area of the world as it was 200 million years ago?

Could these "fissure eruptions," where lava spewed from cracks in the earth's crust, have had an influence on the course of life on earth?

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