THE DEPOSITS OF THE SEA-BOTTOM. 



The whole number of specimens examined by me, amounts to 91. Two of these, nos 94 and 

 98, I have not been able to class positively; both consisted of larger grains of sand and pieces of 

 shells, and have probably been washed during the hauling up, which has also partly been the case 

 with a few of the other specimens; these I have not thought fit for determination with regard to 

 their contents of carbonic acid, and the classification of them is therefore less reliable. Of the 89 

 specimens 7 have by me been referred to shallow-water deposits, of which one must be characterized 

 as gravel, viz. no. 127 at the northern coast of Iceland, and 5 as sand, viz. one specimen no. 6 at the 

 southern coast of Iceland and four specimens at the western coast of Greenland, while one (near the 

 coast of Jan Mayen) has been called Black clay. The remaining 82 specimens are all deep-sea deposits, 

 of which 18 have been characterized as Gray deep-sea clay, 28 as Globigerina clay, while 33 

 specimens form a transition between those classes, and therefore have been named Transition clay. 

 Three specimens filially have been classified as Brown deep-sea clay on account of their peculiarly 

 strong brown colour; they are upon the whole nearly related to the Transition clay. In using these 

 appellations I have chiefly followed Schmelck in his Account of the Norwegian North- 

 Atlantic Expedition, where he uses the following names: Grey Clays and Brown Clay, the 

 latter again comprising two classes, viz. Transition Clay and Biloculina Clay. By this classi- 

 fication regard has only been paid to the colour, which is chiefly dependent on the degree of oxidation 

 of the iron. But as this quality, at least as far as the specimens examined by me are concerned, scar- 

 cely can be said to be specially characteristic, specimens of a gray colour for inst occurring side by side 

 by specimens of a more brownish colour without any possibility of adducing certain rules of the distribu- 

 tion of these colours, I have laid particular stress on the amount of carbonic acid, and have placed the 

 limit between the Gray clay and the Transition clay at 5 — 10 per ct. CaC0 3 , and between the Transition 

 clay and the Globigerina clay at ca. 30 per ct. Ca CO s . The appellation of Biloculina Clay of Schmelck 

 I have not found expedient to use, as it seems to be rather accidental what genus of the larger Fora- 

 minifera is to be found most abundantly in the deposits; South of Iceland the genus Biloculina oc- 

 curs only to a very small degree in the specimens; and even between Iceland and Jan Mayen, where 

 it is found in greatest numbers, it plays no prominent part; of the six specimens of Globigerina clay 

 found in this part of the sea, only the two easternmost (nos 112 and 113) contain greater numbers of 

 Biloculina while the rest on an average contains one for every gram of the specimen. In putting the 

 limit of the Globigerina clay at ca. 30 per ct. CaC0 3 I have followed Murray, who in the account of 

 the Challenger Expedition divides the marine deposits into the following classes: I. Littoral 

 Deposits, II. Shallow-water Deposits, stretching from low-water mark to a depth of 100 fathoms, 

 and III. Deep-sea Deposits, which are again divided into Terrigenous Deposits and Pelagic 

 Deposits. To the Terrigenous Deposits are referred: Blue Mud, Red Mud, Green Mud, 

 Volcanic Mud, and Coral Mud; to the Pelagic Deposits: Pteropod Ooze, Globigerina 

 Ooze, Diatom Ooze, Radiolarian Ooze, and Red Clay. I have, as Murray, placed the limit 

 between the deep-sea deposits and the shallow-water deposits at the depth of 100 fathoms, as all the 

 specimens from lesser depths, with the single exception of no. 115, consist of sand or gravel, while all 

 specimens from larger depths consist of clay. Murray's appellation of Blue Mud corresponds to what 

 I have named Gray deep-sea clay; the blue tone of colour was only found in part of the specimens 



