REVIEW OF OLD AND NEW STANDARDS OF PLEISTOCENE DIVISION 441 



relations between the varve clays, the Os formation, and the annual 

 terminal moraines have been demonstrated by tracing them in numerous 

 places. 



In this manner De Geer was able to trace the retreat of the land ice 

 from year to year through Sweden. The retreat was accomplished very 

 gradually in Scania and Blecking, about 75 meters a year. Farther 

 northward it increased to 100 meters or a little more, up to the great 

 central Swedish moraines. These indicate distinct adverse climatic 

 conditions. Then the retreat set in more powerfully ; it was accomplished 

 with considerable speed and regularity and only occasionally was inter- 

 rupted by a stoppage or a small advance. The record of the retreat 

 fluctuates from 100 to 300 meters or more a year. 



Let us briefly summarize the results of De Geer and his students. The 

 retreat of the ice during Daniglacial time (see figure 3) — that is, 

 from the terminal moraines representing the maximum advance of the 

 Fourth, or Mecklenburgian, Glaciation over the north German lowland 

 and Denmark to the moraines across middle Scania, the southernmost 

 peninsula of Sweden — is unknown. Allowing 50,000 years from the 

 present to the first maximum advance of the Fourth (Wiirm) Glaciation 

 (chart by Soergel and Eeeds, figure 11), it is estimated to have taken 

 33,500 years. The retreat in Sweden during the Gotiglacial epoch — 

 that is, from the terminal moraines in middle Scania to the southern 

 border of the great Fennoscandian moraines south of Stockholm — took 

 about 3,000 years; the Finiglacial time — that is, the retreat from the 

 southernmost of the Fennoscandian moraines to the parting of the land 

 ice in south Jamtland— represents 2,000 years. This totals 5,000 years. 

 The upbuilding of the Fennoscandian moraine zone, which is included 

 as the initial part of the Finiglacial epoch, has been determined by 

 Sauramo (1918.1) in Finland to be 225 years for the outer moraine, 252 

 years for the inner moraine, and 183 years for the intervening territory — 

 a total of 660 years. 



From the annual layers deposited in the valley of the river Anger- 

 manalven, Antevs says that Liden has determined the postglacial time 

 as 8,500 years in lenglh. Postglacial time to Swedish geologists is the 

 time since the division of the land ice into two parts at Ragunda, in 

 north Sweden. This gives 13,500 years for the determined retreat of 

 the land ice of Glaciation IV across Sweden from central Scania to the 

 present small ice-caps in north central Sweden. To this we might add 

 3,000 years as an estimate of the time for the early undetermined por- 

 tion of the Gotiglacial stage in south Scania — that is, 16,500 years from 

 the supposed beginning of the Gotiglacial Stage to A. D. 1900. 



