Evolution of Mammals (66-3 mya)
Global View - Where was Nova Scotia?
Early in the Tertiary Period, the land masses were shaped roughly as we see them today and approached their present global positions. Nova Scotia was located on the eastern coast of the North American continent at the edge of the ever-widening Atlantic Ocean.
Click here to see an animated image of the Atlantic Ocean forming. (127k)
Rocks of Nova Scotia
There is no evidence of new rocks deposited onshore of Nova Scotia during the Tertiary Period. Thick offshore deposits on the continental shelf, however, continued to record the widening of the Atlantic Ocean and rise and fall of sea level.
In the Middle Tertiary, Nova Scotia was part of a crustal block which was uplifted and tilted. Sea level dropped to at least 200 m below the present level and much of the continental shelf was exposed. Vigorous erosion commenced and the soft, unmetamorphosed sediments were stripped off, exposing an ancient landscape of resistant ridges, hard blocks and ancient buried river valleys.
Drainage systems that had formed on the tilted surface became more deeply entrenched. Coastal features which had originally formed during the Carboniferous Period were revealed and the Minas Basin and Chignecto embayments began to develop. On the Scotian Shelf, the relatively level plain was dissected into hills and valleys, which became underwater banks and channels when sea level rose again.
The hard igneous and metamorphic rocks of northern mainland Nova Scotia, Cape Breton and the southern Uplands were not worn down appreciably and became more prominent in the landsape as the surrounding soft sediments were removed around them.
During the Late Tertiary, sea level rose relative to the land, and the previous coastline was drowned. Distinctive coastal features (such as the Bay of Fundy, Bras d'Or Lake, Canso Strait and St. Marys Bay) were flooded, together with other river estuaries and coastal embayments. The essential character of the landscape and coastline of Nova Scotia, reflecting its geological and erosional history, was established at this point and was modified only by the glaciation that came later.
As Nova Scotia approached its present global position, the climate also became more like the one we enjoy today. Near the beginning of the Tertiary Period, the climate was warm and temperate. The land area was presumably densely forested. When sea level rose during the Late Tertiary, much of this forested area would have been flooded by the relatively warm salt water.
The last few million years of the Tertiary Period saw a gradual change in climate. Temperatures dropped steadily, leading into the severe freezing conditions of the Ice Age to come.
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