THE DATE OF THE GLACIAL PERIOD. 613 



summit of the mountains about thirty miles northeast of 

 Beirut and depositing an extensive moraine upon which the 

 present grove of the Cedars of Lebanon are growing. The 

 height of the summit is a little over 10,000 feet, and the glacier 

 descended to the level of 5,000 feet above the sea. The mo- 

 raine is about three miles broad at the foot, and extends five 

 miles back toward the summit, and is several hundred feet 

 thick at its termination. Though not directly connected 

 with the Jordan Valley the climatic conditions accompanying 

 the formation of this glacier doubtless extended a long dis- 

 tance in that direction and so may account for the enlarge- 

 ment of the Dead Sea indicated by the abandoned shore- 

 lines, the most persistent of which is 650 feet above its present 

 level. (See "Records of the Past," July, 1906, pp. 195-204.) 



Such are, in brief, the considerations which seem to make 

 it proper to hesitate before recognizing the theory of discon- 

 tinuous pleistocene epochs in America as an established 

 doctrine to be taught. The most of the facts adduced to 

 support the theory of distinct epochs are capable of explana- 

 tion on the theory of but one epoch with the natural oscil- 

 lations accompanying the retreat of so vast an ice-front. It 

 seems more likely that the retreat from the extreme border 

 of the glaciated area to the line of the moraines of the several 

 later glacial epochs was analogous to that from one to another 

 of the successive twelve or thirteen receding concentric lines of 

 moraine appearing on our general map and on that of 

 Minnesota made from the latest reports, than that successive 

 glacial advances should so nearly duplicate the first as it is 

 made to do on the other theory. 



After a painstaking discussion of the whole subject, 

 Professor Prestwich expresses it as his opinion that — 



The time required for the formation and duration of the 

 great ice-sheets in Europe and America (the Glacial period) 

 need not, after making all allowances, have extended be- 

 yond fifteen thousand to twenty-five thousand years, instead 



