PRELIMINARY REPORT. 21 



smaller and isolated islands as Tikei, Aki-Aki, Nukutavake, and Pinaki, as 

 well as the Gloucester Islands, rise from greater depths and are isolated 

 peaks. At any rate, these soundings indicate, as do the soundings off the 

 Fijis, that atolls do not necessarily rise from very great depths, and that 

 in this characteristic atoll district, atolls are found, it is true, with steep 

 slopes, but rising from moderate depths. The slopes of these atolls would 

 probably resemble in every respect the slopes of the elevated coralliferous 

 limestone islands characteristic of the Lau Group in Fiji, where they have 

 not been obliterated by erosion, denudatioil, and atmospheric agencies. 



The deepest sounding among the Paumotus was on the line to the 

 northward of Hereheretue in the direction of Mehetia, where we found a 

 depth of 2524 fathoms, and a continuation of the red clay characterizing 

 the soundings since we left Pinaki. In nearly all the soundings among 

 the Paumotus, even at moderate depths not far from the atolls, we 

 brought up manganese particles or small manganese nodules. The last 

 haul, made in deep water on the way from Hereheretue, in 2440 fathoms, 

 on the way to Mehetia, brought at least half a ton of manganese nodules, 

 the bottom being red clay. 



We steamed about 2000 miles among the Paumotus, and although 

 we had not the advantage of the accurate surve3's of the English Hydro- 

 graphic charts, which made the exploration of Fiji so easy, yet from 

 the structure of these atolls it was a comparatively simple task, by steam- 

 ing around the islands and landing wherever practicable, to get a fairly 

 good idea of their structure. We have seen notiiing in this more ex- 

 tended examination of the group tending to show that there has any- 

 where been subsidence. On the contrary, the existing condition of the 

 atolls of the Paumotus cannot, it seems to me, be explained on any 

 other theory except that they have been formed in an area of elevation ; 

 an area of elevation extending from Matahiva on the west to Pinaki in 

 the east, and from the Gloucester Islands on the south to Tikei on the 

 north, although the islands in the line of Mangareva to Tahiti are sep- 

 arated from the other Paumotus by a deep channel, nearly 200 miles 

 wide and more than 2400 fathoms in depth, with scattered islets and 

 atolls extending from Mangareva to Piuiiki, and northward to Puka-ruha 



