Lake Agassiz
The Rise and Demise of the World’s Greatest Lake
By Bill Redekop
Sometimes during times of deep thoughts, like when I’m waking up from an excellent nap, I wonder about other vocations I might have pursued if I were to live my life over. One of those is a geologist. As I become fully awake, reality sets in and I realize that I might not have been particularly fond of the lengthy and rigorous outdoor explorations that could have been involved. However, what doesn’t go away is an envy of the knowledge that geologists possess about the natural landscape around us. I’ve often found myself wondering about various geological features. What caused the Rocky Mountains to look the way they do? Why are the Black Hills of South Dakota there? Why does Newfoundland have such extraordinary geological features? And of course, living in Manitoba, why is the land around the Red River so flat? Why do the large dunes at Spirit Sands exist? Why is the Assiniboine Valley so massive in western Manitoba? Why do I so quickly encounter clay when I dig in our yard? I’ve accumulated a small collection of books over the years to help me answer some of these questions, but a good one on the geology of Manitoba seemed sadly lacking.
The recent book by Bill Redekop, Lake Agassiz: The Rise and Demise of the World’s Greatest Lake, has done an excellent job of filling much of that void. The book explores the creation and impact of Lake Agassiz, possibly the largest lake that has ever existed, documents the efforts of key people responsible for its discovery, and much more. That such a large lake was challenging to discover was, of course, because it doesn’t exist any longer. Lake Agassiz was the massive lake that covered much of southern Manitoba (and beyond) several thousand years ago as the latest incursion of glaciers melted during their retreat northward.
A key to the quality of the explanations in the book is that Redekop readily admits that, prior to deciding to write it, he knew very little about the subject. In his words, he possessed “appalling ignorance” of the subject. I suspect he can no longer make that claim because his research led him to some excellent people and other sources of information. I believe it was his initial ignorance that allowed him to write about the subject in a way that the rest of us could understand and appreciate.
Even though the geological parts of the book interested me the most, Lake Agassiz also reminds us that, a mere few thousand years ago, North America used to be inhabited by now-extinct animals (such as mammoths, 11-foot-tall bears, sabre-tooth cats, and giant sloths), how and when humans moved into the area, and what you might have caught while fishing in Lake Agassiz. The book also provides a glimpse of some historical figures who were key to deducing the past existence of kilometers-high glaciers that once covered Manitoba, and who pieced together the clues that provide our modern understanding of the creation, evolution, and eventual disappearance of Lake Agassiz.
While describing the many geological features resulting from the most recent glacial period and its aftermath, Redekop also points out how poorly identified these features are for tourists and the province’s residents. Manitoba’s geology might not be as blatant and showy as some places, but there’s much to be appreciated in the story behind the numerous subtle but extraordinary and fascinating escarpments, hills, valleys, lakes, eskers, moraines, and ancient beaches that can be found throughout the province.
Oh, and if I haven’t yet convinced you that reading Lake Agassiz will be worth your time, you’ve got to be intrigued by a book that contains a chapter entitled “Churchill is Hurtling Skyward”. It’s a fascinating and very satisfying read.
- Cal Brown