JUAN DE FUCA LOBE OF CORDILLERAN ICE SHEET 339 



70 miles back from the front of the glacier, and indicates an average 

 gradient of its surface of at least 80 feet per mile for that distance. 

 It is probable that the front, which terminated in the open Pacific, 

 was cHffed, and that this gradient must be reduced accordingly. 



Based on similar evidence, the surface gradient of the Puget 

 Sound Glacier averaged at least 47 feet per mile for 50 miles back 

 from its front. In both cases, these are but minimum values for 

 the thickness and gradient. 



Acknowledgments are due to the Washington State Geological 

 Survey under which the field work was done on which this paper is 

 based. 



