The physiographic regions of Canada are described at a web page at thecanadianencyclopedia.ca entitled: Physiographic Regions.
Included in the descriptions are references to the physical formations known as drumlins, a topic of special interest to me.
A Nov. 5, 2006 Guardian review of the latter book notes: “In one passage, Munro refers to the ‘glacial geography’ of Canada and the existence of maps that show how the Ice Ages shaped the landscape. She is undertaking something similar on the level of culture, charting the remains and the permanent scouring effects of the retreating glacier known as Presbyterianism.”
That is a powerful metaphor, in my view: The scouring effects of the retreating glacier can be viewed from both a literal and figurative perspective.
The canadianencylopedia.ca web page referred to above provides the following context for the drumlins in Ontario:
St Lawrence Lowlands
“The St Lawrence Lowlands (180,000 km2, 1.8 per cent of Canada’s land surface) lie between the Shield to the north and the Appalachian Region to the east and southeast, and are broken into three subregions [of which the first is described below]:
West St Lawrence Lowland
“This subregion lies between the Shield and lakes Huron, Erie and Ontario. The West St Lawrence Lowland consists of a limestone plain (elevation 200–250 m) that is separated by a broad, shale lowland from a broader dolomite and limestone plateau west of Lake Ontario. This plateau is bounded by the Niagara Escarpment. From the escarpment the plateau slopes gently southwest to lakes Huron and Erie (elevation 173 m). Glaciation has mantled this subregion with several layers of glacial till (i.e., an unsorted mixture of clay, sand, etc.), the youngest forming extensive, undulating till plains, often enclosing rolling drumlin fields.
“Prominent moraines on the western plateau and north of Lake Ontario mark temporary pauses in the retreat of glaciers, between 14,500 and 12,500 years ago. Level clay and sand plains, which were deposited in glacial lakes, fringe the present lakes.”
[End of excerpt]
Physiography of Southern Ontario (1984)
In the past year, I have read many definitions and descriptions of drumlins, in preparation or writing the post you are now reading. I enjoy knowing about drumlins and the physiographic and geomorphological features of Earth. I look forward, as well, to learning the distinction between physiography and geomorphology.
Wherever I find myself, whether walking, running, driving a car, or flying in an airplane, my mind turns to details such as the sloping qualities of the terrain, and similar indications of where the water has run, in the past tens of thousands of years, from higher to lower points.
I think about the origins and history of tectonic plates, the moon, the solar system and outer galaxies, and the universe.
I don’t know much about any of these topics but enjoy reading about them. I’m looking forward to slightly advancing my understanding of mathematics, to help me to get a better grasp of these topics.
Put and Chap
I have written previously about Alice Munro, about her approach to the reading of short stories written by other authors, and related topics of interest.
So, here’s how she describes The Physiography of Southern Ontario (1984), one of my favourite books about physical geography, which is written in a characteristically friendly, crisp, and authoritative form of language. Munro’s description is from a passage in The View from Castle Rock:
“We have special maps that we travel with. They are maps sold to accompany a book called The Physiography of Southern Ontario, by Lyman Chapman and Donald Putnam – whom we refer to, familiarly but somewhat reverentially, as Put and Chap. These maps show the usual roads and towns and rivers, but they show other things as well – things that were a complete surprise to me when I first saw them.”
[End of excerpt]
Munro’s descriptions go on at some length; I’ve just excerpted brief segments from them.
The used copy of the book that I have bought online has a single map in an envelope at the back of the book. I will be interested to know if more than one map was included in the original publication. The copies of the book that circulate at the Toronto Public Library all appear to be missing the map or maps. The reference copies of the book appear to have just one removable map at the back, from what I can recall, but maybe there is more than one map.
Alice Munro describes drumlins
She also describes drumlins [the text is from a scan of the book; being a scan, it may not be a perfectly copy edited version of the text, particularly with regard to some details of punctuation; I’ve returned to the library the copy that I had borrowed, and so am not able to do a proper copy edit of the text]:
“Look at just one map – a section of southern Ontario south of Georgian Bay. Roads, towns and rivers appear, as well as township boundaries. But look what else – patches of bright yellow, fresh green, battleship gray, and a darker mud gray, and a very pale gray, and splotches or stretches or fat or skinny tails of blue and tan and orange and rosy pink and purple and burgundy brown. Clusters of freckles. Ribbons of green like grass snakes. Narrow fluttery strokes from a red pen.
“What is all this?
“The yellow color shows sand, not along the lakeshore but collected inland, often bordering a swamp or a long-gone lake. The freckles are not round but lozenge-shaped, and they appear in the landscape like partly buried eggs, with the blunt end against the flow of the ice. These are drumlins – thickly packed in some places, sparse in others. Some qualifying as big smooth hills, some barely breaking through the ground. They give their name to the soil in which they appear (drumlinized till – tan) and to the somewhat rougher soil which has none of them in it (undrumlinized till – battleship gray). The glacier in fact did lay them down like eggs, neatly and economically getting rid of material that it had picked up in its bulldozing advance. And where it didn’t manage this, the ground is naturally rougher.”
[End of excerpt]
Whether the description “neatly and economically” accords with the science, I don’t know. It’s one of the details of the history of drumlins that I look forward to exploring. I welcome your comments. I have a lot to learn about drumlins.
A You Tune animation showing one possible way that drumlins may have been formed can be accessed here. Plan and profile diagrams of a typical drumlin can be accessed here. It’s my understanding that a unified theory for drumlin formation has not been developed. An overview of drumlin theories can be accessed here. It has been noted that the drumlins near Westover (see photos at the start of this post) are ringed by old shorelines of glacial lakes Whittlesey and Warren which existed about 13,000 years ago.
Glacial Lake Iroquois shoreline
One of the map details (above) from Chapman and Putnam (1984) shows the Glacial Lake Iroquois shoreline as it existed in what is now the City of Toronto. A more detailed map of the shoreline, from Google Maps, can be accessed here:
Lake Iroquois Shoreline: The approximate location of the historic Lake Iroquois shoreline through Toronto (Note that you can zoom in or zoom out on the image, using the buttons at the bottom right of the map.)
Please note: For many of the images at this post, if you click on them, you can get a closer view.