,v DEPTHS AND DEPOSITS OF THE OCEAN 199 



of the Azores, Madeira, etc. The position of the Coral mud 

 deposits of the West Indies and Bermuda is, however, indicated 

 on the map, and these deposits cover an area of about half a 

 million square miles (or 2 per cent of the total area). 



After the Blue mud, the principal type of deposit in the 

 North Atlantic is Globigerina ooze, which covers an area of 

 about 9 million square miles (or 39 per cent of the total area). 

 A glance at the map shows what an extensive area is occupied 

 by this type of deposit in the open ocean, where it is found in 

 greater depths than is usually the case in the other ocean-basins 

 (the "Michael Sars " deepest sounding in 2966 fathoms, for 

 example, gave a Globigerina ooze with 64 per cent of calcium 

 carbonate) ; it also occurs in the Caribbean Sea, in the Gulf of 

 Mexico, and in the Norwegian Sea in lat. 63° N. to 72° N. 



Red clay, which covers such an enormous area of the sea- 

 floor in the great Pacific Ocean, plays a subordinate part in the 

 North Atlantic, being estimated to occupy about 2^ million 

 square miles (or 1 1 per cent of the total area) ; it occurs in two 

 areas on either side of the mid- Atlantic ridge : the larger to the 

 west of the ridge, surrounding Bermuda and extending from 

 lat. 13° N. to 40° N., the smaller to the east of the ridge in lat. 

 8^ N. to 28° N., with a subsidiary area in the Caribbean Sea in 

 lat. 13^ N. to 15' N. 



Pteropod ooze, though widely distributed throughout the 

 basin, covers in the aggregate a comparatively very small area, 

 estimated at about 200,000 square miles (or i per cent of the 

 total area) ; it occurs in the open ocean in the neighbourhood of 

 the Azores, Canaries, Bermudas, and West Indies, as well as 

 in the Mediterranean, Caribbean, and Gulf of Mexico. The 

 other two types of pelagic deposits, Radiolarian ooze and 

 Diatom ooze, are not represented in the North Atlantic. 



Although the "Michael Sars" Expedition did not add "Mic 

 greatly to our knowledge either of the depth or of the deposits s^ampies!^°'''' 

 of the North Atlantic, still both the soundings and the deposit- 

 samples are of value, many of the deposit-samples, indeed, being 

 extremely interesting. A detailed description of all the samples 

 will be reserved for a later publication, but in this place we may 

 refer to the more interesting points brought out by a study of 

 the m.aterial. 



In the first place, reference may be made to the stones and 

 rock fragments brought up from several stations, which form 

 the subject of a report by Drs. Peach and Home appended to 



hael 



