REVIEW OF OLD AND NEW STANDARDS OF PLEISTOCENE DIVISION 439 



interglacial phases correspond with the lower portion of each of these 

 terraces in the fluvio-glacial regions. (9) The arrival of Chellean man 

 does not correspond to lower Quaternary time, but dates solely from the 

 Tyrrhenian epoch of the terrace of 30 meters. In the preceding epochs 

 of Sicilian terraces (90-100 meters) and Milazzian terraces (55-60 

 meters) no industrial or other evidence of the existence of man in Europe 

 has thus far been found, leaving aside the question of eoliths (Deperet, 

 1921.1, page 126). The Chellean industry corresponds Avith the base 

 of the 30-meter terrace. The Acheulean industry occurs higher up on 

 the 30-meter terrace. The Mousterian industry occurs on the 18-20-meter 

 terrace. The Aurignacian industry occurs in the upper part of the 18-20- 

 meter terrace. In the final Magdalenian industry the valleys were nearly 

 down to their actual present level. 



6. POSTGLACIAL GEOCHRONOLOGY OF SWEDEN, FINLAND, AND NORTH 

 AMERICA OF DE GEER (REVISED BY DR. E. ANTEVS) 1 



Bruckner, in the Zeitschrift fur Gletscherkunde, July, 1921, pages 

 39-57 (Bruckner, 1921.1), discusses the work of De Geer and his junior 

 colleagues. This review is of special interest to American students of 

 this problem, since Bruckner was joint author with Penck of the epoch- 

 making work "Die Alpen im Eiszeitalter," 1901-1909 (Penck and 

 Bruckner, 1909.1). 



De Geer's Method, which permits the determination of the Postglacial 

 epoch in absolute measurements of time and a geochronology of the re- 

 treat of the land ice, was developed in the vicinity of Stockholm. It 

 consists of the examination, measurement, and coordination of the sea- 

 sonal layers of banded clay of glacial origin which were deposited in the 

 Baltic and in various lakes that covered extensive parts of Sweden during 

 the retreat of the land ice of the Fourth, or last, Glaciation. Many 

 of these deposits now appear as land above the level of the Baltic. 



Each annual layer consists of two deposits — a lower, summer layer, 

 which is thicker, of more sandy material; an upper, winter layer, which 

 is thinner, of darker color and of very fine clay, deposited in the following 

 winter. In various exposures numerous annual layers are superimposed 

 one above another. In recording them the thickness of each seasonal 

 layer is marked on the margin of a long strip of paper. As the character 

 of the weather during the melting period varied from year to year, these 

 fluctuations are reflected in the varying thicknesses of the annual deposits. 



7 In February, 1922, Dr. E. Antevs read the portion of this manuscript dealing with 

 the De Geer chronology and made a few suggestions and additions which have been in- 

 corporated in the present paper. 



