Introduction. 39 



constantly drifting 1 from the Siberian coast, and that, 

 while passing" through the unknown and cold sea there 

 is time for it to attain its enormous thickness partly by 

 freezing, partly by the constant packing that takes place 

 as the floes screw themselves together. 



I further mentioned in the same lecture that the mud 

 found on this drift-ice seemed to point to a Siberian 

 origin. I did not at the time attach great importance to 

 this fact, but on a further examination of the deposits I 

 had collected during my Greenland Expedition, it 

 appeared that it could scarcely come from anywhere else 

 but Siberia. On investigating its mineralogical compo- 

 sition, Dr. Tornebohm, of Stockholm, came to the 

 conclusion that the greater part of it must be Siberian 

 river mud. He found about twenty different minerals in 

 it. " This quantity of dissimilar constituent mineral 

 parts appears to me," he says, " to point to the fact 

 that they take their origin from a very extensive tract of 

 land, and one's thoughts naturally turn to Siberia." 

 Moreover, more than half of this mud deposit consisted 

 of humus or boggy soil. More interesting, however, 

 than the actual mud deposit were the diatoms found in 

 it, which were examined by Professor Cleve, of Upsala, 

 who says: "These diatoms are decidedly marine (i.e., 

 take their origin from salt water), with some few fresh- 



O / ' 



water forms which the wind has carried from land. The 

 diatomous flora in this dust is" quite peculiar and unlike 

 what I have found in many thousands of other speci- 



