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Prehistory- The Secrets of the Stones

The Secrets of Crab Island: Part I

Prehistory: The Secrets of the Stones

by James P. Millard

Crab Island first began keeping her secrets some 450 million years ago. The region we now know as Lake Champlain was but a small part of a large, shallow, tropical sea. The region was warm and the waters teemed with ancient life. Vast coral reefs with all their colorful diversity, brachiopods (what we today would call shellfish), gastropods (snails), creatures strange and common- crinoids, cephalopods, bryozoans and trilobites were everywhere.

(Click for map)

Hundreds of millions of years passed; continents collided, the Earth was in the midst of great Another view of the fossil seen at left. Click on the thumbnail to see a full-size image.Extraordinary fossil from Crab Island, most of the fossils found along the shore are brachiopods and gastropods. Click on the thumbnail to see a full-size image.upheaval. Great mountain ranges, much higher than we see today, sprang up on each side of what became a deep valley. The teeming ocean was forced away as the region literally rose from the depths of the Earth. The life that was within these seas was buried in the muck and mud of the valley. Over time, much time, this mud became limestone and shale. Crab Island- itself a limestone mountain, began to keep the first of her secrets- embedded within the rocks along her shores would be millions of fossils. These are vestiges of life from ancient oceans- hundreds of millions of years old.

Fossils in the rocks at Crab Island (click on the thumbnails to see a large image)  Fossils in the rocks at Crab Island (click on the thumbnails to see a large image)  Fossils in the rocks at Crab Island (click on the thumbnails to see a large image)
Fossils in the rocks at Crab Island
(click on the thumbnails to see a large image)

James G. Bailey in his "The Forgotten Graves of Crab Island" tells us that the island may have received its name from "a species of mollusk which a casual observer might easily mistake for crabs." 1

That is probably true, but this writer prefers to believe the name was chosen because of the abundance of fossils in the rocks along the shore. When I see a trilobite, I think of an ancient crab...

This planet is constantly in flux. The time humans have resided here is but an instant in the timeline of Earth's history. For hundreds of millions of years, the region was submerged under vast seas, hemmed in by the loftiest of mountains. Then, some 5 million years ago, the ice came.

Massive glaciers covered the region; the change could not have been more profound. Reaching at times to a depth of over a mile, these mighty sheets of ice scoured the earth to bedrock and depressed what earth remained beneath them. Then, a mere 20,000 or so years ago the great ice sheet began to recede. Slowly, the enormous glaciers melted, leaving behind a vast freshwater lake. These melt waters stayed in the region, held back from the sea by the mass of the huge glacier to the north. Some 15,000 years ago, Lake Vermont was formed 2.

Lake Vermont wasn't here very long, in a geological sense. Within a couple of thousand years, the glaciers to the north had melted sufficiently to allow sea water to rush in to the area, depressed as it was by the sheer weight of the ice sheet that at one time covered it. The freshwaters of Lake Vermont gave way to the briny depths of the Champlain Sea. The rise of land we know as Crab Island in all likelihood projected out of an ocean once again.

Another cataclysmic change was in the making. Human beings would find their way to the shores of the Champlain Sea.

Crab Island would hold secrets anew...

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1  James G. Bailey, "THE FORGOTTEN GRAVES OF CRAB ISLAND" (The Antiquarian-Fall 1988, Allan Everest, Editor Clinton County Historical Association, Plattsburgh, NY) 1
also republished with permission: America's Historic Lakes, < > May 2001

2 Lake Champlain Maritime Museum, Geological History, < > (16 May 2002) link expired, no further information available

On November 11, 2002, Crab Island was featured in a WPTZ/Lake Champlain Basin Program Champlain 2000 story.


Visiting Crab Island...
Crab Island is publicly owned land- the property of the people of New York. It is also a very special, unique place that merits respect and consideration. Keep in mind the island is covered with Poison Ivy. It is also the home of protected fauna and flora. Look, but do not touch. Metal detectors and digging are strictly prohibited on the island.

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