Paul
Karrow,
Quaternary
Sciences
Institute,
University
of
Waterloo,
Waterloo,
Ontario,
N2L
3G1
Publication
QSI
PFK
11
But this bar is dry! Yessir, you'll get mighty thirsty looking for a drink at this bar! When I tell you this bar is actually an old beach, you needn't run to get your bathing suit either, `cause the water's long gone!
About 10 - 11,000 years ago, the edge of glacial Lake Algonquin was bordered by high shorecliffs like those today along Lake Huron between Point Clark and Grand Bend. At the mouth of each river valley the waves moved sand and gravel along shore to build bay mouth BARS, which enclosed quiet water lagoons in behind. One of the largest in southern Ontario formed across the Saugeen River valley between Port Elgin and Southampton. This massive ridge parallels Highway 21 along the east edge of town, and is the site of several old gravel pits. A similar but smaller bar formed across the Penetangore River at Kincardine.
In the quiet waters of the Saugeen lagoon, thick deposits of silt were deposited by the river over several centuries. In these silts can be found fossil remains of the animals (snails, clams, ostracodes) and plants (leaves, seeds, pollen grains, pieces of wood) that lived in the water and along the shore. These tell us the climate was much colder than now, not surprising when you realize the north shore of Lake Algonquin was the retreating glacier. The pieces of wood have allowed us to date the lake, with ages ranging 11,300 to 10,500 years ago.
Lake Algonquin came to an end when the retreating glacier opened a lower outlet at North Bay and the water level dropped some 100 m from well above to far below present Lake Huron level. There must have been a spectacular flood of water that escaped down the Ottawa Valley into the Champlain Sea near Pembroke.