14 THE ROYAL SOCIETY OF CANADA 



the valley between the drift ridges at New Westminster, now occupied 

 by the Fraser river existed at the time of the marine incursion. It 

 is probable, therefore, that considerable erosion of the drift deposits 

 had taken place prior to the deposition of the shell beds. 



The fossil shells, as determined by E. J. Whittaker of the Canadian 

 Geological Survey, are of 20 species. Restates: "The fauna is quite 

 comparable with the inshore fauna of the British Columbia coast at 

 the present time. Most of the species range from Behring Sea to 

 Puget Sound. The assemblage represents a typical mixture of inter- 

 tidal and shallow water forms." At the two localities mentioned — 

 Kitsilano and near New Westminster — numerous well preserved 

 molluscan shells occur. Several specimens with both valves attached 

 and closed and filled with sand were dug out of the stony clay. This 

 mode of occurrence and the fact that they occur only in the upper 

 part of the clayey till and not scattered through it shows that they 

 have not been transported but lived nearly in the position in which 

 they are found. They show that at the time of their deposition the 

 sea stood 50 to 100 feet higher than it does at present. 



Fossil shells have been found also in wells in the drift near 

 Central Park and as far up the Fraser valley as Murrayville, 2 miles 

 east of Langley Prairie. At these places the surface material is till 

 and the shells are reported at various depths, from 15 to 30 feet and 

 at various heights up to 350 feet above sea-level. It is not certain in 

 what material the shells occur and it is possible that at these localities 

 the shells are not in place. 



Although it is not possible to trace the marine horizon definitely 

 throughout the district it is probable, because of the general similarity 

 of the mode of occurrence of the fossils, that the horizon is a single 

 one and extends over a considerable area in the Fraser valley. The 

 marine deposits show that some time during the Pleistocene period 

 the sea entered the Fraser valley following a retreat of the ice-sheet, 

 and the till which ov^erlies the marine beds shows that a readvance 

 of the ice-sheet took place. The position of the marine horizon in 

 the upper part of the Pleistocene series, the fact that in places the 

 marine beds are overlain not by till but by stratified deposits only, 

 and the evidence that the valley in the drift deposits above New 

 Westminster existed at the time of the marine invasion, appear to 

 show that the readvance of the ice-sheet occurred late in the Pleisto- 

 cene and was more or less local in character. 



The occurrence is a remarkable one when it is considered in 

 connection with the character in general of the Pleistocene deposits in 

 the region. It is the only marine horizon known in the Pleistocene 



