Nr. 6] KVARTÆR-STUDIER I TRONDHJEMSFELTET 169 



Mellersta hvitåsand och hvitålera 0'o/(//a-lera, Gadiis /;o/«//.s-lera > 



Undre niorån 



Undre hvitåsand och hvitålera 



»Arctic freshwater bed ^ 



Undre i'oW/«-lera och Bridhngton crag 



Cyprina-\era och Leda /»ya//s-lagret 



»Skogen i Cromer 



Norwich Crag 



Red Crag 



Coralhne Crag. 



Dog maa vi iier erindre, at allerede flere aar tidligere hadde 

 John William Dawson i sit Supplement lo the second Edition 

 of Acadian Geology«, London 1878, pag. 27 — 28, for Kanadas 

 vedkommende foreslaaet følgende Subdivisions of the Pleistocene 

 Deposits : 



1. Pealy lerrestrial surface anlerior lo boulder clay 



2. Lower stratilied gravels (Syrlensian) 



3. Boulder clay and unstratified sands wilh boulders Fauna 

 extremely Arctic) 



4. Lower Leda clay wilh highly Arctic shells 



5. Upper Leda clay and sand (Uddevalla beds, many sub Arclic 

 or boreal shells) 



(>. Saxicava sand and gravel (wilh lilloral sliells of boreal or 

 Acadian types). 



Og Dawson omtaler ved samme leilighel beds of Leda clay 

 passing upwards into sand and gravel' (L. c. pag. 2.S). Del 

 samme fænomen fremstilles ogsaa i Reports on a I^orlion of 

 Algoma and Thunder Bav Dislricts ()ntario< bv W. .1. Wilson 

 (Canada, Dept. of Mines, Geol. Surv. No. 980 (1909), pag. 81— 32\ 

 hvor der meddeles: The whole county is deeply covered with 

 clay through which the rivers have cut deep, canal like chan 

 nels, in piaces lo a deplh of 40 or 50 leet. Tbe clay banks 

 frequenlly show a dislinct line of separation about midway uj). 

 The lower balf is hard and usually stands at a sleeper angle 

 ihan thai above, and contains many large and small slriated 

 boulders. Tbc iippcr |)arl sbows slralilicalion, and for a con 

 siderable dislance from Ibe mouibs of tbe rivers bolds mariue 

 shells, Sd.vicand nujosd being especially abundanl, and Mdcoina 

 calcaria and Mi/d (irriKirid are also fairly common. On llu' 

 Nagagami Ibe sbells were found about seven miles froui llu' 

 moiilli, bul above Ibis, allbougb tbe clay seemed tbe same, no 

 sbells were found. On Ibe I\ei)inakagauii Ibey were seen for 



twelve miles up Ibis clay is evidently the ecpiivalent 



of Ihe Leda clay of easlern Canada . Jeg har gil et saavidl ul 

 førligt citat af deu interessante beskrivelse netop fordi \i bcr 



