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GEOLOGY OF THE TORONTO REGION

 

The leaves and wood belong to more than thirty species, which include Asimina triloba, Carya albs, Chamaecyparis sphaeroidea, Crataegus punctata, Juniperus virginiana, Maclura aurantiaca, Platanus occidentalis, Prunus, Robinia pseudo-acacia, Taxus canadensis, Thuja occidentalis, Tilia americana, and several species of ash, poplar, oak and elm, and two extinct species of maple. The whole assemblage of trees indicates a climate decidedly warmer than Toronto at present, about like that of Ohio or Pennsylvania.

The section at Scarborough Heights, some miles east of Toronto on the shore of Lake Ontario, includes 36 feet of sandy beds with unios and wood beneath the water level, 90 feet of peaty stratified clay, and 55 or 60 feet of stratified sand. The peaty clay encloses a little wood, fragments of leaves, mosses and seventy-two species of beetles, of which only two still live. The stratified sand contains wood and a few small shells. The fossils are considered to indicate a climate somewhat cooler than the present, like that of Lake Superior, for example.

The Scarborough beds are evidently delta deposits laid down in a lake rising 150 feet higher than Lake Ontario. Later the lake was drained and valleys were cut in the delta by rivers, as may be seen at a striking bit of cliff architecture called the " Dutch Church." This is carved by rain and stream erosion from boulder clay which filled the old valley during the second ice advance.

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