322 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1931 



Figure 5. — Retreat of the last ice sheet in northeastern NDith America. (Moraines 

 in the Eastern States from various sources ; moraines in the Middle West from 

 Leverett and Taylor, 1915, p. 62 ; and moraines between the lakes from Taylor, 

 1924a) 



R., Ronl<onkoma ; H. H., Harbor Hill; T. M., terminal moraine; M., Mississinawa ; D., 

 defiance ; A., Alden ; N. F., Niagara Falls ; P. II., Port Huron. The estimates of the 

 time of release of the belt between Lake Ontario and Mattawa River is probably too 

 long. The figure 26,000? at Mattawa and 29,000? at Cochrane should be altered to 

 21,500? and 24.500?, respectively. Tlie length of time since the ice sheet reached 

 its climax in Long Island is probably 35,000 years, in round figures. (From Antevs, 

 Amer. Geogr. Soc, Research Ser. No. 17, fig. 29) 



