THE DEPOSITS OF THE SEA-BOTTOM. 



41 



from Iceland ; on account of the large quantity of coarser material, especially in the specimens nos. 2, 

 3, and 4, it is to be supposed that at least the larger part has its origin from the ridge itself. The 

 fact is that we can find no possible reason whatever why the material from Iceland should be depo- 

 sited in very small quantities on the deeper water, while deposited in so enormous masses on the two 

 ridges reaching from Iceland to the Faroe Islands and Greenland. The same reason must, at all 

 events, be appliable also to the ridge running from Iceland to the southwest, but here are found exactly 

 the same small quantities of the coarser material on the ridge as on both sides of it. The difference 

 between the deposited quantities of coarser ingredients may be so large, that for inst in specimen 

 no. 143 north of the Faroe Islands is found 1500 times as much as in no. 139 situated about 80 kms. 

 north of the preceding one. Such a difference would be absolutely incomprehensible, if we do not sup- 

 pose that this coarser material has its origin from the sea-bottom itself. But a consequence of this 

 supposition will again be, that from the nature of this material we may get a notion of the outline 

 of the petrography of the sea-bottom. It will then be seen that that part of the ridge, which is clo- 

 sest to Iceland, consists of volcanic material of about the same nature as that of Iceland itself, that 

 is to say, chiefly black basalt, some volcanic tufa etc. These rocks spread over almost the two thirds 

 of the length of the ridge towards the Faroe Islands. But closest to these islands, at least on the 

 northern side of the ridge, a quite different sort of rocks is found; the specimen no. 143, especially, 

 that is so very rich in coarser ingredients, has none of these volcanic rocks but on the contrary large 

 masses of fine-grained rocks rich in quartz. In this part the ridge must consequently be taken to 

 consist of older formations, partly crystalline rocks as granite and gneiss, and partly quartzite or sand- 

 stone. Also in the part of the ridge closest to Iceland, some regions of similar rocks are likely to be 

 found, or else it will be rather difficult to comprehend, how they should have found their way into 

 specimen no. 4, in which some of them are found, although most of the specimen is volcanic. The 

 amount, however, is too small to allow our drawing definite conclusions to that effect. 



South of Iceland the volcanic ingredients decrease more rapidly than in any other direction; 

 as has been mentioned before, a larger series of specimens is found here, containing no great amount 

 of volcanic material, but on the contrary rather large quantities of quartz, the presence of which seems 

 rather difficult to explain. Towards the southwest the volcanic ingredients spread farther out again, 

 so that in specimen no. 19, west of Cape Farewell, they are present in as large quantities as the not 

 volcanic, and in specimen 110.21, directly south of Cape Farewell, they are still found in appreciable 

 quantities in the largest distance, to which the material is upon the whole removed from Iceland. 

 Here we shall also necessarily have to think of the ice as an acting factor. The East-Greenland cur- 

 rent must be supposed casually to carry with it some material from the northern coast of Iceland; 

 but it seems nevertheless remarkable that this material does not disappear so completely in the large 

 mass of Greenland material, as to be only with difficulty distinguished in the specimens. At least it 

 will be as improbable to suppose submarine rocks in this deep part of the sea-bottom that is covered 

 by so regular and fine deposits, as the case is here. 



If we next proceed to the specimens situated between Iceland and Greenland, we shall find 

 the circumstances quite analogous to those existing on the ridge between the Faroe Islands and Ice- 

 land. Here we also find irregular deposits the nature of which is suddenly changed from one specimen 



The Ingolf-Expedition. I. 3. 6 



