THE DEPTH AND MARINE DEI'OSITS OF THE PACIFIC OCEAN. 155 



north to 2° south latitude, the southern boundary coinciding with the 

 parallel of 2° south. A third considerable area of Globigerina Ooze sur- 

 rounds the Caroline archipelago, and a fourth surrounds the Marshall and 

 Gilbert archipelagos, while several small isolated areas surround the scat- 

 tered groups of islands, and cover the summits and flanks of some sub- 

 marine elevations. It will be observed that generally the Globigerina Ooze 

 is found in depths between 1000 and 2300 fathoms, while the Red Clay is 

 found in depths exceeding 2300 fathoms. There are, however, important 

 exceptions to this statement. 



III. Diatom Ooze. — This type occurs in the form of two broad bands, 

 the larger in the far south and the smaller in the far north. The south- 

 ern one forms part of the circumpolar band surrounding the Antarctic 

 continent, outside the band of Blue Mud, and covers an area of about two 

 and a half millions of square miles, while the northern one stretches 

 across the northern boundary of the Pacific, from Japan on the west to 

 Vancouver on the east, and covers over a million square miles. One of 

 the most interesting results of the recent expedition of the "Albatross" 

 is the discovery of this type of deep-sea deposit, so characteristic of high 

 latitudes, within the tropics, viz., in latitude 12° south, off the west coast 

 of South America, where, however, it has apparently a very restricted 

 area of distribution. 



IV. Radiolarian Ooze. — This type covers two large and two or three 

 small areas in the tropical part of the Pacific. The most important one 

 is the comparatively narrow band in latitude 10° north, stretching from 

 165° to 80° west longitude, and covering an area of nearly two million 

 square miles. A second area, nearly a million square miles in extent, 

 stretches from latitude 8° north to 12° south, and from longitude 180° to 

 164° west. Of the other smaller areas, one occupies the Challenger Deep 

 in the North Pacific, extending from 143° to 147° east longitude and 

 from 12° to 15° north latitude, and two lie in the South Pacific, one in 

 latitude 3° to 8° south and longitude 151° to 153° west, the other in lati- 

 tude 10° south and longitude 156° west, 



V. Pteropod Ooze. — It is rather curious to note the absence of this type 

 in the northern and eastern Pacific, the most northerly and easterly posi- 

 tion hitherto known being latitude 9° south and longitude 139° west in the 

 Marquesas group. Several small areas of Pteropod Ooze are dotted over the 

 western portion of the Globigerina Ooze area of the South Pacific, especially 



