42 0. B. B0GGILD. BOTTOM DEPOSITS. [norw. pol. exp. 



in the two places. In Greenland the loose deposits play a very small part. 

 The coast almost everywhere consists of solid rocks, and nearly all the rivers 

 flow upon rocky ground. In consequence of this, all the constituents come 

 out into the ocean as nearly in their original condition as possible. Some of 

 the heavier minerals will probably be altered, but their percentage in the 

 sand of the sea-bottom will still be not much less than in the original rocks. 

 A great part of Siberia, on the other hand, consists of sedimentary material, 

 of which probably a large proportion has its origin at a great distance, and 

 has undergone numerous transportations before reaching the ocean. 



A comparison of these percentages with those known from other places 

 is also extremely interesting. Schroeder van der Kolk gives a very large 

 number of measurements of sand-samples from Central Europe, and shows 

 that in diluvial sand of Scandinavian origin there are percentages of heavier 

 minerals that as a rule are higher than 0'5, while sand-deposits of more 

 southern origin as a rule have smaller quantities. Thus the deposits at the 

 north of Siberia answer with tolerable exactness to the first kind of diluvial 

 sand, of which samples from Denmark, England, North Germany, and North 

 Holland have been examined. As the deposits on shore from which the 

 material of the ocean-floor comes, cannot have a smaller percentage of heavier 

 minerals than this material itself, we thus have a means of comprehending 

 the great extent to which the Silurian loose rocks have undergone transpor- 

 tation and subsequent deposition. 



The differences between the percentages for the several samples are due 

 in a great measure to purely local causes; the various localities obtain their 

 material from widely different parts of the coast. The large percentage in 

 No. 3 is characteristic, that sample being taken from a locality not very far 

 from that of No. 6, which would lead us to expect that their sandy particles 

 would be of a similar nature. The difference can arise from the fact that 

 while the greater part of the constituents of No. 6 emanates from the coast 

 of Siberia or from the neighbouring Kjellmanns Island, No. 3 has obtained 

 its materials, at least partly, from Sverdrups Island. Different current condi- 

 tions can also have played their part in the separation of the materials. The 

 comparatively large percentage (2'45) in No. 15 is more immediately connected 

 with the circumstance that this sample gets its material from the most eastern 

 part of Siberia, where the country is rather rich in solid rocks; and it is there- 



