SHELL-BEDS IN BRITISH COLUMBIA. 277 



shells were not noted in the lowest portions of the drift. They are 

 generally contained in hard fawn-coloured sandy clay, almost with- 

 out stratification, and are frequently quite decayed and crumbling, 

 though found with the valves united in the position of life. Granitic 

 fragments included in the clay are also very frequently more or less 

 decomposed, and sometimes completely rotten, showing that car- 

 bonated surface-waters here long acted on the mass since its ele- 

 vation. This action may probably account for the comparative 

 scarcity of the shells, while its continuance for a period somewhat 

 more prolonged would without doubt have resulted in their total 

 removal. The beds so affected are at a height of only a few feet 

 above the sea ; and this, coupled with their resemblance in texture 

 to many inland drift-deposits, suggests one means of accounting for 

 the apparently complete absence of marine remains over areas which 

 on other evidence appear undoubtedly to have been at one time 

 submarine, but which from their elevation must have been much 

 longer exposed to the percolation of surface-waters. 



" The following species have been recognized among the fossils 

 hitherto found : — 



Cardium islaudicum. 

 Leda fossa. 

 Saxieava rugosa. 



Natica clausa (probably). 

 Balanus crenatus (probably). 



" In localities where the upper sandy and gravelly layer of the drift 

 is not developed, the change from deep-water to littoral conditions 

 appears to be marked by the rather sudden introduction of car- 

 bonaceous matter, changing the clayey deposits from their usual 

 pale tints to dark brown. In some places the marine shells, and 

 especially the Cardium above named, appear sparsely in the highest 

 layers of the pale clays ; while in other localities, near the present 

 shore-line, the lowest layers of the shell-heaps, and burnt stones 

 used by the Indians in cooking, coincide with those of the brown 

 earth, showing apparently that the last movement of elevation by 

 which the land attained about its i)resent level was rather sudden, 

 and that habitation by a race resembling the present natives followed 

 closely on the termination of the glacial conditions. 



" The general appearance of the deposits of this part of Van- 

 couver Island, resting, as they do, on planed and polished rocks 

 perfect in every detail and necessitating glacier-action for their 

 explanation, and yet consisting of water-bedded and often current- 

 driven materials mingled in places with sea-shells, leads to the 

 belief that they were formed along the retreating foot of a glacier 

 which had extended some distance beyond the margin of the land. 

 The withdrawal of the ice may have been caused or accompanied 

 by subsidence ; and some species of shells must have followed its 

 front pretty closely in its retreat. The somewhat irregularly 

 terraced form of the deposit is probably due to action during emer- 

 gence ; and the general tendency of many facts is to show that a 

 slight sinking of the coast is at present in progress or has lately 

 occurred." 



