. The Canadian field-naturalist. Wilson: Geology of the Ottawa District 27 Avenue crosses the broken fragment between the Farm hill and the hill just west of Bronson Avenue. In that fallen strip lie The Flats and the railway yards below the Wellington Street and the Somerset Street bridges. South of Carling Avenue, Dow Lake is part of it (p. 14). a) At the Kippewa Drive outcrop note the slope of the rock. The edge of the scarp was pulled down by the force of the sinking valley to the west. Excavations for the houses near Opeongo Road and the digging of the sewer exposed black shale, not grey l
. The Canadian field-naturalist. Wilson: Geology of the Ottawa District 27 Avenue crosses the broken fragment between the Farm hill and the hill just west of Bronson Avenue. In that fallen strip lie The Flats and the railway yards below the Wellington Street and the Somerset Street bridges. South of Carling Avenue, Dow Lake is part of it (p. 14). a) At the Kippewa Drive outcrop note the slope of the rock. The edge of the scarp was pulled down by the force of the sinking valley to the west. Excavations for the houses near Opeongo Road and the digging of the sewer exposed black shale, not grey limestone. Other exposures and well drillings show that the black shale was deposited on top of the grey limestone—another proof that the strip has fallen from its high estate. b) Note the crumbly nature of the rock. Part of that is due to dynamiting for the roadway, but part is due to the breaking along the edges of the fault. c) Note the calcite in the cracks—a feature often found near a fault. Running water dissolving the limestone flows down the cracks. As it evaporates, or as the calcium becomes concentrated, the water desposits the secondary calcite in a crystal- line form. d) There are a few fossils here, but not many. In the flat weathered exposures such as could be found along the avenues before they were built up, corals were present and numerous brachiopods. It is at this horizon that the replacement of the Opikinas by the Rafinesquinas culminates. HOGSBACK Distance: Kippewa Drive to Hogsback 3^2 miles. From the Bronson and Carling avenue intersection drive to Preston Street and thence to the Driveway and the Prescott Highway through the Farm to Hogsback. The name Hogsback (Fig. 8) is given to this outcrop because of the peculiar. Fig. 8. Typical hogsback (Resistant rock caps and protects weaker underlying rocks) structure of the rock. Some of it is folded. The small island block that divides the falls is tilted. It is all supposed to resemble a hog's back. The ex
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