160 ICE-BORNE SEDIMENTS IN MINAS BASIN, N. S. — BANCROFT. 



ice did not attain to the thickness wliich had characterized it 

 during some previous years. 



At tlie moutli of Mud Creek, the thickness of between tifty 

 and sixty cakes of ice which had been left there by the out- 

 going tide was carefully measured. It was impossible to include 

 in these measurements some of the thicker cakes of ice which 

 were floating down the Cornwallis River. The average thick- 

 ness, by this method, was found to be one and a half feet. This 

 estimate was a very conservative one, since the thicker cakes 

 of ice which are stranded, some even ten and twelve feet in 

 thickness, seem to lodge upon the stretch of marsh laid bare 

 upon the opposite side of the Cornwallis River. But in calculat- 

 ing the average, the cake of greatest thickness measured was 

 seven feet thick, another was five feet thick, and the rest ranged 

 from this down to three inches. 



Much attention was given to the selection of those ice cakes 

 whiqh were carrying the average amount of sediment, and for 

 this purpo.se manj^ more cakes of ice were broken open and 

 carefully inspected. Then thirty-four pounds of the ice contain- 

 ing an average quantity of detritus was melted and filtered upon 

 large filter papers in the laboratory. The sand and mud collected 

 on the filter paper was dried in an oven at a temperature of 

 90° C. The weight of the sediment found in this quantity of 

 ice was found to be 1.1 pound. Upon examining portions of 

 this material under the microscope, at least three distinct 

 varieties of diatoms were noticed. From an admiralty chart, 

 the length of the coast line of Minas Basin, was found to be about 

 120 miles, without taking into account the manj^^ small indenta- 

 tions and irregularities of the shore. The width of the tidal 

 flats exposed at low water, from the same chart, was estimated 

 to be about three-fourths of a mile. If these calculations are at 

 all in error, it is due to the estimates taken not being large 

 enough. The amount of ice in the Basin, at the time the experi- 

 ment was performed, was such that when it was low water the 

 tidal flats laid bare were covered with irregular ice masses, and 

 much ice still remained floating. 



