12 THE ROYAL SOCIETY OF CANADA 



as described by Willis and Bretz. Two till sheets have been recognized 

 in both regions — -the lower till known as the Admiralty till and the 

 upper as the Vashon till. Separating the two tills are thick deposits 

 of stratified sand and gravel, silts and clays, known as the Admiralty 

 sediments. Stratified silts, which are probably of Pleistocene age, 

 occur in places below the lower till but no evidence of till older than 

 the silts has been found. Stratigraphically above the upper till, but 

 co\'ering it only in places, are the outwash and delta sands and gravels 

 and stratified clays deposited during the final retreat of the ice-sheet 

 and the Recent delta and alluvial deposits. 



Although the Admiralty sediments are probably in part at least 

 marine because of their position near sea-level and on the coast, and 

 because they consist in part of stratified clays, upwards of 100 feet 

 of which are exposed in the sea cliffs near the International Boundary, 

 they have yielded no marine fossils in the Fraser delta region. A 

 single occurrence of fossil marine shells in the drift deposits near 

 Central Park, between Vancouver and New Westminster, was reported 

 by Burwash,- who thought that the fossils were from the Admiralty 

 sediments but investigation by the writer of the occurrence appeared 

 to show that they were in till, or at least that the mode of occurrence 

 was doubtful, for the shells were found in an excavation for a well 

 in which no good section was exposed. Fossil marine shells in the 

 Pleistocene deposits were, however, found by the writer at a number 

 of widely separated localities in the Fraser delta region. The marine 

 horizon appears to be younger than the Admiralty sediments and 

 older than the latest glacial deposits. 



The fossil marine shells occur at a definite horizon in the drift 

 deposits exposed in the sea clifif extending along the coast for several 

 miles west of White Rock, near the International Boundary. The 

 marine horizon was found at several places in these sections for a 

 distance of about two miles along the coast. It lies at a nearly 

 uniform height in the sections of about 100 feet above sea-level. 

 The shells occur in stony, unstratified clay in a zone a few feet thick 

 near the middle of what appears to be a single till sheet 40 to 50 feet 

 thick. The shelly zone, however, is more clayey and less stony 

 than the till in general; many of the shells are well preserved, and 

 barnacles and worm-shells occur attached to the stones. It is, there- 

 fore, probable that it represents an old sea-bottom ploughed by the 

 advancing ice, which deposited the till. It is not impossible, how- 

 ever, that the shelly till was transported some distance and hence 



2 Ibid., p. 87. 



