76 A MW MODE OF TKAIN'SPOIJTATION Bl r ICE. [vol. lxXV r 



salinity, and in many places is much affected by the river-currents. 

 Mr. Crook's plea for the recognition of overthrust planes can hardly 

 apply to floating sheets of this nature, for they are moving over a 

 frictionless plane, and the parts aground are very local. His 

 question as to the time required for the uplift of the muds is. 

 susceptible to calculation by a method which is outlined in the 

 paper, and may be put in the following form : — 



m- r ,..,. Total thickness of sheet, 



lime or uplitt in years = 



Annual decrease of upper surface. 



Distance from origin to point of first appearance. 



Annual rate of movement. 



In conclusion, he thanked those present for their kind reception! 

 of his paper. 



