40 THE DEPOSITS OF THE SEA-BOTTOM. 



chart, pi. V, given the different mass of volcanic material found in the specimens by different colours; 

 the darkest colour designates the localities exclusively containing volcanic ingredients, or in which 

 the grains of quartz and other kindred minerals and rocks form only a very small part of the specimen ; 

 the next shade designates the localities that are chiefly volcanic, but in which are also found some 

 other ingredients; the limits of this region represent about 90 per ct. of volcanic material inwardly, 

 and 65 per ct outwardly. The next shade of colour denotes the area in which both kinds of material 

 are present in about the same quantity; the volcanic material is here found in an amount of about 

 35 — 65 per ct In the next area the volcanic ingredients are only found in an amount of ca. 10 — 35 

 per ct ; in this region, therefore, the volcanic material is not at all prominent. Outside this area either 

 no volcanic material is found at all, or, at all events, it is found in so small quantities as to be of no 

 importance with regard to the composition of the specimen. By regarding the chart it will be seen 

 that all the volcanic material belongs to Iceland, the Faroe Islands, and Jan Mayen; round the two 

 latter localities it reaches only a small way into the sea; from Iceland, on the contrary, it spreads far 

 away to all sides, .and upon the whole in a rather characteristic way. Towards the north and north- 

 west are not many specimens; yet the few, found there, indicate that the volcanic ingredients do not 

 reach very far upward, but that Iceland and Greenland here exert about the same influence on the 

 composition of the bottom-specimens, each from its own side. When we pass to the north east of 

 Iceland we find, that the volcanic material is widely spread in this direction, and that it is the Ice- 

 landic material may be inferred, primarily from the nature of the material, and next also from the 

 fact that the volcanic ingredients of the specimens decrease towards Jan Mayen, and is not again 

 found in any large quantity until specimen no. 115, lying close to that island. That the volcanic 

 ingredients spreading from Iceland to the northeast, cannot have their origin from the sea-bottom 

 itself, may be seen from the regularity with which they are found in the specimens. The amount of 

 coarser material decreases rather evenly, the more we withdraw from Iceland, and it is upon the 

 whole rather small in the region treated of here. If, on the other hand, submarine rocks also contri- 

 bute some material, this is always seen to be very irregularly distributed, partly, when a larger area 

 is concerned, consisting of very heterogeneous material, partly appearing in very large quantities, which 

 are, however, always much varying from one specimen to the other, according to the circumstances in 

 which the specimen has been taken, whether from a rugged bottom, or close to such a place, where 

 large accumulations are made of the material set free by the disintegration of the rocks or ortherwise, 

 or the specimen has been taken from a comparatively level bottom farther away from projecting rocks. 

 In what way the material of the region in question has been transported from Iceland so far into the 

 sea, is not easily explained; the most likely explanation would seem to be that it has been carried 

 there by the ice, which may have been either coast-ice, or ice from the rivers; but against this sup- 

 position tells the fact that the currents prevailing on the locality in question, pass from the north to 

 the south, and thus this transport would seem to be very much hindered; the floating ice, as is well 

 known, is, however, not absolutely dependent on the currents, but may be supposed to be acted on 

 by the wind also, and this is presumably chiefly southwest in these regions. 



Immediately east of Iceland the volcanic material ceases rather quickly; but on the ridge 

 towards the Faroe Islands it again reaches rather far. Here, however, it does not seem to have come 



