W. A. Johnston — Calcareous Sandstone. 417 



Aet. XXXIII. — The Occurrence of Calcareous Sand- 

 stone in the Recent Delta of Fraser River, Rritish Col- 

 umbia, Canada ; by W. A. Johxstox. 



The occurrence of calcareous sandstone, ^vhich is appar- 

 ently forming in the Recent delta of Fraser river, British 

 Columbia, was brought to the attention of the Geological 

 Survey, Canada, by samples sent in by Mr. W. P. Gross, 

 Engineer of the Department of Public Works, in charge of 

 dredging on Fraser river. The occurrence was examined 

 during the course of an investigation, made during parts 

 of 1919 and 1920, of the characteristics of Fraser river 

 and its delta, and, because of its rarity and unusual char- 

 acter, is here described. 



The Recent or modern delta of the Fraser river is 

 building out into fairly deep water in the Strait of Geor- 

 gia. The delta extends inland for 19 miles and across 

 its seaward front is 14 miles wide. The surface of the 

 delta is practically all below the level of high tide, and 

 the delta land high enough to be reclaimed is diked. Sand 

 banks, exposed in large part at low tide but completely 

 submerged at high tide, form the seaward part of the 

 delta and extend on an average 4 to 5 miles from the 

 higher delta land. A number of distributaries flow 

 through the delta, the main Fraser flowing the central 

 part, the North Arm along the northern side of the delta, 

 and in the southern part a number of smaller outlet 

 channels occur. 



The calcareous sandstone occurs in the sand banks in 

 the seaward part of the delta. It was dredged by the 

 Government dredge near the inner end of the entrance 

 of the North Arm of the Fraser, where a bar was cut 

 through and large quantities of the material thrown out. 

 It was also dredged by the Government dredge and by 

 the writer in the main channel of the river in its seaward 

 part, and by the writer in the seaward part of the old 

 channel of the river south of the present main channel. 

 It is known to the fishermen, who refer to it as ^^ clinkers" 

 and state that it frequently fouls their nets in the channels 

 on the sand banks both north and south of the main outlet 

 channel of the river. It probably does not form in the 

 river channels but in the sand banks, and occurs in loose 

 masses in the channels because of erosion of the sand 



^ Published by permission of the Director of the Geological Survey, 

 Canada. 



