288 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1917. 



Baltic inter stadial. — Arctic marine and fresh-water deposits of 

 East and West Prussia. 



Baltic readvance. — Moraines of the Baltic Hohenriicken. 



2. THE LOWER RHINE VALLEY AND HOLLAND. 



The best basis for correlating the glacial beds of Holland with 

 those of north Germany is given by the Eem zone, which in north- 

 west Germany has been shown to fall in the interglacial between the 

 lower and middle bowlder clays. The same bed has been described 

 from borings at a few points in Holland, and its relations with the 

 other members of the Quaternary series made out. 



The Eem zone was found by Dubois in borings in 1903 underlain 

 by bowlder clay representing the maximum glaciation of Holland; 

 this was confirmed by Lorie (19) in 1905 and 1906. 



In the region north of the Ehine, and south and east of the Zuyder 

 Zee, investigations have been carried out by J. van Baren (20). Two 

 bowlder clays were found, an upper gray bowlder clay and a lower 

 red, sandy bowlder clay of a lateritic aspect. The red color of the 

 latter was shown by G. Leopold (21) to be due to intense weathering; 

 the gray clay is much fresher. The red clay occurs over the whole of 

 the region of Veluwe west of the Yssel "River and is folded into the 

 underlying Tertiary beds, but the gray clay occupies only the prov- 

 inces of Groningen, Drenthe, and Friesland, and nowhere extends 

 west of the Yssel; it is not folded. As early as 1881 its limits were 

 traced by Penck (22) through Gaasterland, Steenwijk, and Embli- 

 cheim to the Vecht. During the interglacial period between the accu- 

 mulation of these two glacial clays, were formed, first peat beds and 

 later, the Eem beds. 



A similar succession was found by Van Calker (23) in Groningen, 

 where a fossiliferous marine sand 15 meters thick, with peat and 

 glacial scratched bowlders, occurred between two bowlder sand beds. 

 Both Van Baren and Van Calker found the lower bowlder clay to 

 contain Scandinavian erratics and the upper bowlder clay Baltic and 

 even Finnish erratics. 



In the province of Gelder, Lorie found the following succession in 

 borings : 



7. " Miniatnrgrand," sand with occasional small bowlders. 



6. Peat, indicating an elevation of about 20 meters above the present. 



5. Marine clay. 



4. Coarse shelly sand, termed by Hurting " Eem system." 



3. Bowlder clay, situated generally 20 to 36 meters below Amsterdam 



datum. 

 2. Rhine sands and gravels. 100 meters thick. 

 1. Pliocene. 



From these sections and descriptions it is evident that the weath- 

 ered bowlder clay below the Eem zone, representing the maximum 



