The Canadian Field-Naturalist; 





VOL. XXXVI 



OTTAWA, ONT., OCTOBER, 1922. 



SOME NOTES ON THE SOOKE FORMATION, VANCOUVER ISLAND, B.C. 



By Ira E. Cornwall, F.G.S. 



ALONG the southwest coast of Vancouver 

 Island several exposures of Tertiary sand- 

 stone are known, representing at least two 

 formations. One of these, the Sooke formation, 

 is exposed at several places between Becher bay 

 and Sombrio river. The largest area of this 

 formation lies in the basin drained by Tugwell, 

 Muir and Kirby creeks, extending for about three 

 miles along the coast. It faces the Juan de Fuca 

 Strait, and has been traced for about three miles 

 inland, where it has been found at an elevation 

 of over 1,000 feet. It rests unconformably on the 

 Metchosin basalts and Sooke gabbro. The sand- 

 stone is covered by a considerable thickness of 

 Pleistocene glacial deposits, clays, sands and 

 gravel. The general dip of these rocks is toward 

 the shore, where wave action has cut into them 

 forming cliffs, which at many places are undercut 

 forming shallow caves. 



The first systematic collection of fossils from 

 this formation was made by Dr. C. F. Newcombe, 

 of Victoria, in 1894 and 1895. Collections were 

 also made by the Canadian Geological Survey.^ 



About half a mile west of Muir Creek the sand- 

 stone forms the beach and has been cut into small 

 table-like projections, some of which are a few 

 feet and others several yards in area. These are 

 caused by the sea cutting through a thin, hard 

 layer of sandstone lying on a softer layer, and are 

 from six to twelve inches high. On the part of 

 the beach uncovered only at the lowest tides 

 are found the sea-urchins, Strongylocentrotus pur- 

 puratus, in cavities which they cut in the vertical 

 sides of these tables. They do not cut deeply into 

 the rock and become prisoners for life, as do some 

 of the urchins on the California coast, but the 

 holes are cup-shaped and just deep enough to 

 cover them. According to A. Agassiz they cut 

 these cavities with their teeth, gnawing at the rock 

 as they incessantly turn around, thus enlarging the 

 cavities as they grow. These little tables, or 

 projections, are also honeycombed by the rock 

 boring Pholas penita. These creatures commence 

 their borings when very small and when they have 

 once made a cavity they become prisoners, only 



their long siphons projecting from the holes. 

 They cut into the rock by constantly turning by 

 means of their foot which projects through a 

 large opening between the anterior edges of their 

 valves. It is the edge of this opening which does 

 the cutting, or scraping, as the creature turns. 

 When the Pholas has reached its full size this 

 opening is closed by the growth of the shell. 

 When broken, the rock is found to contain fossil 

 mussels, Mytilus sp., in great numbers and in a 

 beautiful state of preservation. There are also 

 occasional leaf impressions, some of which show a 

 reed-like leaf with three parallel longitudinal 

 ridges, while others resemble oak leaves. In a 

 piece of sandstone broken off from below low-water 

 mark at the mouth of Sandstone creek, many of 

 the cavities made by the Pholas were found 

 crowded with the long shells of the rock boring 

 Adula stylina, as many as six or eight being found 

 in one opening. None of these shells were found 

 in borings which they had made for themselves, 

 but all in the borings made by the Pholas whose 

 shells, in some cases, still remained in the holes. 

 Evidently the rock in this locality is too hard for 

 the Adula to bore into. 



The writer has collected a number of fossil 

 bones at different exposures of this formation, 

 most of which were collected about four years ago 

 from the cliffs and sandstone forming the beach 

 west of Muir creek. Dr. Othenio Abel, of Vienna, 

 has examined photographs and drawings of these 

 bones, and, while unable to give an exact deter- 

 mination, has stated that they are from a species 

 of small tooth whale. He also draws attention to 

 the resemblance between one of the vertebrae and 

 the lumbar vertebra of Squaledont bariensis, 

 Jourdan,^ from the Miocene of Bulluno in Italy. 

 Another bone about eighteen inches long, he 

 states, resembles, in cross-section, part of the 

 lower jaw of a Mysfacocetan. We have also found 

 pieces of ribs, part of a scapula, and part of a 

 small skull showing the ear opening. These 

 specimens are too fragmentary to be of any real 

 value, but they indicate what may be found in 

 this formation by long continued search. 



