' ' MAEION ' ' EXPEDITION TO DAVIS STEAIT AND BAFFIN BAY 77 



originate from Disko Bay or Umanak Fjord, I would consider quite impossible. 

 Nor does it seem probable that they originate from Kane Basin. In such case 

 an exceedingly strong erosion in connection with an improbably long transport 

 toward the south by the aid of icebergs must have taken place here during 

 glacial times. A transport from Baffin Land seems on the basis of our 

 extremely slight knowledge of the geology of this region to be the most natural 

 explanation, provided we will not explain the process by the aid of considerable 

 subsidences round Davis Strait, Wegener's theory, etc. 



Frosted sand grains. — The frosted well-rounded grains of sand 

 that constitute a very minor part of the sediments, may be of Eolian 

 origin, but they also ma}^ be produced in water by attrition. The 

 apparent decrease in plentifiilness of polished constituents away from 

 shore accords with the Eolian hypothesis. However, even if these 

 frosted grains are of wind origin, the following questions arise : "Were 

 they blown to the neighborhood of their final resting place, either 

 through air or along the surface of the ice; were they blown onto 

 ice and then transported to their place of burial ; or were they carried 

 relatively long distances through the water by currents? Unfortu- 

 nately, insufficient data are available to answer these questions. 



Finely divided calcium carhonate. — Calcium carbonate forms a 

 large part of the fine constituents in most of the sediments; but it 

 has not been practicable to investigate this finely divided CaCOs. 

 It may be a chemical precipitate, it may result from wind-blown 

 calcium carbonate dust; it may be a deposit-like clay resulting from 

 particles suspended in the water, or it may be ice borne. 



In view of the apparent absence of a local limestone source it seems 

 that the ice-borne origin is more probable. This is also supported 

 by the observation that the sediments off Cape Murchison are de- 

 ficient in limestone fragments and that sample 8 from the same 

 region contains a large amount of fine constituents, but almost no 

 CaCO.-,. It would appear from this that the source of debris in the 

 Cape Murchison sediments is to a large extent the adjacent coast of 

 Baffin Land and only to a small degree, floating ice from distant 

 areas. Sample 20, off Aulalsivik, contains no limestone rock frag- 

 ments, and although it is a fine-grained deposit, it contains little 

 CaCOg. In other parts of Davis Strait, limestone is a plentiful con- 

 stituent of the gravel and also calcium carbonate particles form a 

 significant part of the fine fraction of the deposits. Furthermore, 

 because of its softness, limestone is readily abraded by ice action; 

 therefore, one would expect that a considerable quantity of finely 

 divided CaCOs would be trapped in adjacent ice. If" this were 

 carried out to sea it would form a deposit relatively rich in detrital 

 CaCOa. Thus, the ice-borne origin of the calcium carbonate is in 

 accord with all the known facts. Whether or not it is the true 

 explanation will depend on future work. 



CHARACTERISTICS OF SEDIMENTS OF ICE-BORNE ORIGIN 



Two factors dominate the formation of sediments of ice-borne 

 origin; one the heterogeneous nature of the detritus brought by the 

 ice, and the other the action of the currents. The debris brought by 

 the ice is very poorly sorted, and if it falls in a region in which 

 currents are weak, the coefficient of sorting of the deposits will be 



