THE DELAWARE LIMESTONE (MIDDLE DEVONIAN) OF SOUTHWESTERN ONTARIO, CANADA

The Delaware Limestone of southwestern Ontario was originally called a part of the Corniferous Limestone by Murray (184.3-53). Since that time the same outcroppings have been designated, either wholly or partially, as the Onondaga Formation, the Big Lime, Delaware Limestone, Norfolk Formation, Dundee Limestone, Columbus Limestone, and the Dundee (= Delaware) Limestone. As recently as 1971 the names Dundee Limestone and Delaware Limestone were used for the same formation. Hand specimen and petrographic study of samples from nineteen localities in southwestern Ontario indicates that the limestones of the formation exposed on the Niagara peninsula are intermediate in type between the rocks of the Delaware Limestone of Ohio and those of the Dundee Limestone of Michigan. The formation in Ontario becomes more like the Delaware Limestone southeast of the Findlay Arch and becomes more like the Dundee Limestone northwest of it. A comparison of the fauna and flora shows that more key species are common to the Ontario and Ohio formations than to the Ontario and Michigan ones. On both paleontological and historical grounds, the rocks in Ontario should be designated as the Delaware Limestone