THE DEPOSITS OK THE SKA-BOTTOM. 



Gray deep-sea clay along the eastern coast of Greenland; probably it is found in a belt, 100—150 km. 

 broad. We have no specimens of this sort of clay along the south and west coast of Iceland; it must 

 be supposed to stretch in a distance of 40 — 70 km. round the outermost parts of the land. 



North of Iceland the distribution is greater; but it abounds especially to the east of the island 

 where it covers a great area, gradually decreasing in breadth towards the Faroe Islands. West of these 

 islands it is only little found, as the Globigerina clay is already met at station 25, ca. 130 km. from 

 the land; the condition of the sea-bottom south and east of the Faroe Islands cannot be ascertained; 

 perhaps the Gray deep-sea clay is stretching without interruption to Norway and the Shetland Islands, 

 while, according to Murray, a strip of Globigerina clay stretches from the open Atlantic to the 

 northwest of Iceland and Scotland, where it ceases about at the Orkney Islands. Round Jan May en 

 the Gray deep-sea clay is not much found; according to Schmelck the Biloculina clay reaches very 

 close to the island on the north, while the specimen 116 of the Ingolf Expedition, from a distance 

 of about 80 km. south of the island, consists of Transition clay. 



The Gray deep-sea clay may be characterized as a generally rather rich and clean variety of 

 clay of a grayish colour; when dry it is light gray, most frequently very coherent; on more shallow water, 

 closer to the coast, it is commonly much mixed with sand, also often with stony material. The colour 

 is now somewhat lighter, now somewhat darker, sometimes with a slightly bluish tint, but as often 

 slightly brownish or yellowish. After Schmelck the gray colour arises from the degree of oxidation 

 of the iron, the ratio between the sesquioxide and the protoxide of iron being in the gray clay on 

 an average as I'/z^i) while in the brown sorts of clay the same ratio is as 3:1; in the gray clay 

 the iron is accordingly present in its more original condition, while it becomes more and more oxidized, 

 as we get farther from the land. The amount of carbonate of lime in the Gray deep-sea clay is rather 

 small, the terrigenous ingredients being completely void of lime; it varies from 0-26 to 6-14, and generally 

 it is of course largest at the border of the transition clay. After Schmelck the amount of carbonate 

 of lime rises in some places to more than 20 per ct; but as these highly lime-charged specimens are 

 also mentioned as being of a brown -gray colour, I do not understand why they are referred to this 

 category, and no inference can thus be drawn from these numbers. 



The Transition Clay covers the sea-bottom as a more or less broad belt between the Gray 

 deep-sea clay inwardly and the Globigerina clay outwardly. On an average it begins at a depth of 

 about 500 faths, and reaches to a depth of about 1000 faths; but from this there are innumerable 

 exceptions on account of the different localities. On the west coast of Greenland the Transition clay 

 begins at about 62° Eat. N.; from this place it stretches as a broad belt round the southern point up 

 along the east coast In this part of the sea it is found to a very large depth, reaching at station 37 

 to 1715 faths, the largest depth but two upon the whole measured during the Ingolf Expedition. The 

 Challenger Expedition, however, has taken Blue Mud, which also includes the Transition clay, on far 

 greater depths, in a few places even on 2800 faths; but such cases must be considered as quite excep- 

 tional. South of Iceland the Transition clay is widely spread, and sends out, as it were, a low tongue 

 into the Atlantic, which does not, however, coincide with the ridge stretching from Iceland to the 

 southwest, but is situated to the east of this ridge. On both sides of the ridge between Iceland and 

 the Faroe Islands the Transition clay stretches as a rather narrow belt; round Jan Mayen it is only 



The Ingolf Expedition. I, 3 z 



