QUATERNARY DEPOSITS OF BRITISH ISLES BROOKS. 281 



2. The various moraines and fluvio-glacial terraces differ extraor- 

 dinarily both in their morphological form and in the depth to 

 which they are weathered, varying from quite fresh moraines with 

 unaltered surface forms and a very slight degree of weathering, asso- 

 ciated with equally slightly weathered fluvio-glacial gravels, to old 

 " senile " moraines, with forms so strongly denuded as often to be 

 unrecognizable, associated with very deep-going and generally in- 

 tense weathering, both in the moraines and in the gravels. 



3. Between the various groups of moraines and fluvio-glacial sedi- 

 ments are often found extra-glacial deposits containing remains of 

 warmth-loving faunas and floras which according to our present ex- 

 perience can not have lived at the edge of a continental ice sheet. 



As an example he compares the very worn moraines of Schleswig- 

 Holstein, the Elbe Valley, and Silesia, weathered to a depth of 10, 

 12, and even 20 meters, with the rough, fresh looking moraines of 

 the Baltic Hohenriicken, weathered to a depth of only 1.25 to 1.75 

 meters. The former are deeply weathered, even where they pass 

 under the latter, and are often separated from them by deposits in- 

 dicating a temperate climate. Gagel remarks that it is difficult to 

 escape from the conclusion that the weathering of the one, 10 to 

 20 times as deep as the other, must have required 10 to 20 times as 

 long. After a critical examination of all the interglacial deposits 

 known to him, being 22 marine and 111 lacustrine interglacial de- 

 posits and 45 zones of weathering, he finds them all referable to two 

 important characteristic horizons, which are shown at seven places 

 by direct superposition in the same section and at five places by un- 

 doubted stratigraphical correlation in closely neighboring sections. 

 In the younger horizon the marine deposits always underlie the 

 lacustrine, in the older horizon they overlie them, indicating a con- 

 siderable sinking of the land in the middle glacial period. Gagel 

 has therefore no hesitation in adopting the hypothesis of a threefold 

 glaciation of Germany by ice from the north. Of these the oldest 

 was the most extensive and the youngest the least so, and he corre- 

 lates them with the Mindel, Riss, and Wurm glaciations of the Alps. 

 He finds no equivalent of the Gunzian glaciation, and in the terraces 

 corresponding to the first interglacial of the Alps there is no northern 

 material. 



The type sections of this series are those near Berlin, at Rixdorf, 

 and Phoeben. The section at Rixdorf is as follows : 



5. Upper bowlder clay. 



4. Thick diluvial sands. 



3. Bed of coarse gravel with remains of large mammals. 



2. Middle bowlder clay. 



1. Paludina bed with P. diluviana. 



