THE ICE AGE AND THE FORMATION OF THE ISLAND

When I planned the content of this blog it was to include, after a number of introductory and biographical posts, a chronological and thematic overview of PEI Heritage, prehistory and architecture as I knew it and had presented it in my lectures over the past forty years. Lectures are ephemeral things and dissipate with the audience. I want now, at this late time in my life, to record the contents of those lectures – the result of so much work and time and passion – so that it will survive in a more tangible way after I am gone.

 

HOW DID WE GO FROM THIS TO THIS?

The word “heritage” has many shades of meaning. Generally, we speak of it as something passed down from our ancestors – an inheritance. We can also look at heritage as natural – the total of everything that makes up biodiversity. This includes flora and fauna and the earth on which we live – how we live on it, what we have done to it and what we will do to it in the future.

To understand our natural heritage we need different kinds of maps, and in this post I will provide you with a number of them that will take you on a journey from the formless masses of glacial ice to the road maps we use today to make practical sense of our environment.

Long before human being occupied this region there had been geological processes that had been going on for billions of years. The most recent of these processes was the last Ice Age, called by geologists the Pleistocene Epoch which began about 2.6 million years ago and ended, in our region, about 11,000 years BP. Here is a graphic that shows the extent of the ice over the Maritime region about 20,000 years ago. Everything was covered but nothing was static; there was movement everywhere.

When I began my study of Island prehistory, I checked every resource I could find to determine when it became possible for human beings to move in and exploit the resources that could be found there. Fifty years ago, the story of the retreat of the glaciers – at least what was available to a non-scientific audience – was a simple one: a warming climate caused the ice to melt and retreat to the North. As the ice moved away, its heavy burden, often more than a mile thick, allowed the compressed crust of the earth to rebound, revealing land masses that had been hidden for millennia. To complicate the story, in time the freshly revealed land masses began to be submerged once again, this time covered by water from the melting of the glaciers. It was in that scenario that human beings first occupied parts of what we now call “the Island.” The maps I had access to in those early years were fairly primitive, often little more than rough indicators.

A few years ago, having learned that the Bedford Institute of Oceanography in Halifax had been mapping the floor of the ocean off Eastern Canada in order to determine all sorts of things such as when land masses were visible or drowned, and how the present contours of this land finally became settled. They used many techniques to gather this information, from remote sensing with sonar and analysing cores of sea bottom to establish their ecological evolution.

It was while searching for information and maps on this great survey that I came across a wonderful site called CoastWeb – Progression of sea-level change in Atlantic Canada, put out by Natural Resources Canada at www.nrcan.gc.ca .  It was a collection of the most wonderful maps showing the evolution of Maritime topography as the ice retreated.

Driven by Divine Providence, I downloaded the contents of this site, and another related one on the earlier glacial period, and saved them as WORD documents. It had been my intention, when I reached this part in my blog, to insert the link so that readers could enjoy for themselves this amazing resource and all this new knowledge. The link is sadly no longer active and I have not been able to find this material in any other location. However I believe that I can make use of these maps for educational purposes and do so in that spirit. Should this not be legal then, upon notification, I will delete the post. In the meantime I will post a series of details from these maps that show how land masses that form Prince Edward Island changed over the last 20,000 years. For your information I provide below my two docx files saved as pdf in case you want to check my sources more closely.

NRCAN – Geographic change in the glacial period, Eastern Canada

NRCAN – Progression of sea-level change in Atlantic Canada

Twenty thousand years ago the whole region, except for the east edge of the Grand Banks and banks off the new England coast were covered with a layer of ice so thick – at least one mile! – that I find it difficult to imagine.

By 13,000 years BP Eastern PEI was free of ice and its land mass at East Point, and the shoreline going west, were considerably larger than they are today. Significantly Saint Peter’s Bay appears to have been an inland lake at that time. This is highly important for the archaeological record and will be touched upon in a later post.

At this time Prince County, with low elevations even today, consists of two islands made up of the high ground. The largest, which varies from 25 to 45 metres in elevation, is the area between O’Leary and Tignish. The smaller “island” is made up of ground of similar elevation between Wellington and the former Mount Pleasant Airport. The Magdalen Islands are vast!

Two thousand years later in 11,000 BP, the Island as we know it is recognisable although it is a little bigger than it is now. The process of rebound has begun, and more land emerges from the water as the earth’s crust rises.

All the North Shore bays – Cascumpeque, Malpeque, New London, Tracadie, Savage Harbour, Saint Peter’s and the tiny North Lake are all ponds or drainage areas. The same can be said for all the Eastern water features starting with South Lake and going down to Murray Harbour. On the South side of the Island the vast Pownal Bay is a lowland area free of water, as is Bedeque Bay. Again, there are archaeological implications regarding traces of human settlement that today is completely submerged.

Just another thousand years and the landscape changes in the most amazing way! By 10,000 BP the rate of the earth’s crust rebounding has increased to the point where the Island is no longer an island but is joined to New Brunswick and Nova Scotia from Summerside to the Wood Islands area. The land mass increased in every direction. Humans living on the Island would have had to go out much farther to reach the shore’s edge, and any activity they engaged in there would eventually be submerged under deep water.

And that was not all. The next two thousand years, from 9,000 to 8,000 BP would see an even more spectacular series of rebounding events as can be seen in these two details from the large maps.

By 9,000 BP the extent of visible land mass seems to have been at its greatest. PEI was enclosed in a massive land mass from Northern New Brunswick straight to Cape Breton Island. The Magdalene Islands, still greatly enlarged, would have been clearly visible from the Island mass and communication would have been an easy thing. One can even speculate whether it would have been possible to actually walk to the Magdalens. All this has further archaeological implications because of evidence, which I will discuss in another post, of the same kind of stone being used to make tools and weapons both on the Magdalens and PEI with its source in what would have been the hills of Ingonish in Nova Scotia, not yet eroded into an Island. As well, there is compelling evidence that at this time a special, very beautiful quartzite was imported all the way from Labrador!

A thousand years later things have begun to change as the sea levels rise and land masses shrink. PEI is not so close to the Magdalen Islands any longer and it is possible to see that a long extension of the North Cape Reef has detached itself as the currents of the Gulf of Saint Lawrence turn at the east of Gaspé and descend along the shore almost to Cape Wolfe. Northumberland Strait is being born!

By 6000 BP the Island exists once again as a body surrounded by water. Northumberland Strait has established is powerful and complicated currents that have cut away a great deal of land to form the contours familiar to us today. Bedeque and Pownal Bays, low sandy areas, will soon open up into bays and drainage patterns from streams and rivers will begin to cut through the land, creating the complicated but beautiful contours we enjoy today.

It is of the utmost importance that we note that the humans now living on the Island witnessed its birth as an island and saw the shores of New Brunswick and Nova Scotia erode further and further from view. The Island was now here to stay. It was now only a question of a couple more thousand years before the rising waters would rough out the complicated coastline that we call our home today. That coastline is forever changing, especially along the North Shore as more and more land, the weaker parts of the geological substrate, erode into the Gulf of Saint Lawrence.

Nothing is ever static. Here, residents, on a daily basis even, witness the ever-changing edges of their homeland.

 

WHAT THE RETREATING GLACIERS LEFT US

It is now possible, through various sources, to obtain maps that provide all sorts of specialised information. One of vital interest to us, and fascinating to study, is the topographic map that shows all the land elevations on the Island. From it we can separate the hilly country from the lowlands and speculate what might have drawn various kinds of settlers through the long ages to select one piece of land over the other. These, as it were, are the bare facts after the ice had gone and the coastlines taken on their relatively stable outlines that we know today.

https://en-ca.topographic-map.com/maps/qu5/Prince-Edward-Island/

We can use the information on this map to figure out why people settled where they did, very long ago or just yesterday. The lay of the land is a very powerful inducement to the selecting of a place where life can be maintained, or aesthetically enhanced.

There is another special map that ties in closely with this one. It too is a topographical map but one that shows us exactly what the retreating glaciers left us on the ground. That was a vast quantity of various kinds of rocks carried thousands of miles and which had no relation to our sandstone base. This sort of map is called a surficial geology map and, in the Canadian Centennial celebrations of PEI joining Confederation in 1973, such a map was produced for the first time. It was masterminded by the geologist K. V. Prest and was called Surficial Deposits of Prince Edward Island – Map 1366A. It was published by the Geological Survey of Canada, Department of Energy, Mines and Resources in Ottawa in 1973. Here is a graphic of the complete map and below, a pdf file provided by GEOSCAN. (Special thanks to Phil Culhane for finding this for me.)

Prest – Surficial Geology 1973 – recto

And here is the back of the map showing glacial movements and deposits, as well as a fascinating essay on the map and its contents.

Prest – Surficial Geology 1973 – verso

What confusion appears! The topographical map is simple to interpret compared to this. That is because the Prest map records what and where the melting glaciers left on the Island as the mass of ice moved away, from piles of exotic stones to deep gouges in the ground. It is a strange mixture with huge differences of coloured reference areas in the three counties. To determine exactly what is on the ground – and therefore what would attract different people for different kinds of settlements – we need this key.

Now you are equipped to begin your studies of the Island in its most elemental form!

Here is a simple road map to reorient yourself to the lay of the land you perceive as you move about day to day. It completely obliterates – unless you have a sharp eye – all the other traces of the remote past I discussed in this post.

 

AS YOU LEAVE, REMEMBER THE REMOTE PAST WHEN HUMANS, JUST LIKE US, SETTLED THE ISLAND FOR THE FIRST TIME.

It is best to conclude this map study with a reminder that, as far as we can tell, human beings came to the Island as soon as the retreating ice permitted them to do so. They hunted and gathered and fished and had temporary settlements, probably on a seasonal basis. That makes sense. They were forced to move away from the shore as their settlements eroded from under them and constantly move inland, leaving, as they went, many of their belongings like their tools and weapons. And they left a lot of  detritus, usually around massive camp fire sites, of the many specialised rocks, both local and imported from very far away in the forms of discarded flakes and splinters. It is all we have to tell their story of occupation, perhaps all 13,000 years of it.

 

REFERENCE MATERIAL

CoastWeb – Progression of sea-level change in Atlantic Canada, put out by Natural Resources Canada at www.nrcan.gc.ca   (link is non-functional)

DeGrace, John R., “In the Story of the Earth: The Page Called Prince Edward Island,” The Island Magazine, Prince Edward Island Museum, Charlottetown, Number 46, Fall/Winter 1999.

Fensome, Robert K. and Williams, Graham L. editors, The Last Billion Years: A Geological History of the Maritime Provinces of Canada, Atlantic Geoscience Society, Nimbus Publishing, Halifax, 2001

Prest, V. K., Surficial Deposits of Prince Edward Island – Map 1366A, Geological Survey of Canada, Department of Energy, Mines and Resources, Ottawa, 1973.

Prest – Surficial Geology 1973 – recto

Prest – Surficial Geology 1973 – verso

Van de Poll, H.W., Geology of Prince Edward Island, Energy and Minerals Branch, Prince Edward Department of Energy and Forestry Report 83-1, Charlottetown, 1983.