BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 31, pp. 319-328 June 30, 1920 



EXTENT AXD THICKNESS OF THE LABRADOE ICE-SHEET ^ 



BY A. P. COLEMAN 



(Presented before the Society December 30, 1919) 



CONTENTS 



Page 



Tiitroductiou 319 



(xlacial features of the Torngats 320 



Ice boundary in the Gulf region 321 



The Gaspe driftless area 323 



Thickness of the ice-sheet 324 



Thickness of the ice in the Adirondacks 325 



Relations to isostasy 326 



Introduction 



The Labrador ice-sheet did not cover the whole of eastern America 

 north of New York, since the Torngat region, in northeastern Labrador, 

 and the Shickshock Mountains, in Gaspe, escaped and remained as drift- 

 less areas. On the other hand, in places the ice-sheet passed beyond the 

 present eastern edge of the continent, covering part of the shallow sea 

 bottom along the coast of Labrador and occupying most, if not all, of 

 the present Gulf of Saint Lawrence. On the western side the ice-sheet 

 at its greatest extent filled the basins of Hudson and James bays, thus 

 meeting the Keewatin sheet. Just how far it extended southwest is not 

 quite certain, its relations to the Patrician sheet described by Tyrrell 

 being still only imperfectly known. The island of Newfoundland is be- 

 lieved to have been an independent glacial center, adjoining the Labrador 

 sheet on the east. 



It is proposed in this paper to define the eastern limits of the Labrador 

 sheet, referring specially to the driftless areas ; to estimate the thickness 

 of the sheet at various places, and to discuss the relation of the ice burden 

 to postglacial raised beaches and to the theory of isostas}^ 



1 Manuscript received by the Secretary of the Society February 30, 1919. 



XXII— BrLL. Geol. Soc. Am.. Vol. .SI, 1919 (319) 



