H48 
THE VOYAGE OF H.M.S. CHALLENGER. 
earthy matter of a yellowish brown colour, mixed with depositions of the oxides of iron 
and manganese. Two ice-borne fragments of granite, covered with manganese, are noted 
as having been obtained at this station, but these have not been preserved in the 
collections. 
Pacific Ocean. 
Station 175, 1350 fathoms. — The trawl brought up a branch of a tree and a large 
number of fragments of pumice. The pumice fragments vary much in size, the largest 
being 6 to 8 cm. in diameter. They had all undergone considerable alteration, the 
surfaces being covered with hydroxides of iron and manganese. The fragments effer- 
vesced when treated with acid, owing to the presence of Foraminifera shells, the deposit 
having infiltrated in some cases into the pores, as well as the oxides of iron and manganese. 
Most of the fragments may be referred to augite-andesite, while others belong to the basic 
series and have rounded pores. In thin sections under the microscope it can be seen 
tliat in the external altered zones the manganese has been introduced following exactly 
the contours of the scoriaceous rock. It might be said that a replacement of the 
pumice had taken place, but in a certain sense it is rather an impregnation or mould- 
ing. This structure, however, apparently reappears in many of the manganese nodules 
at other stations, where all trace of the pumice has disappeared, but where, from all 
appearances, the nodules were originally formed around fragments similar to those above 
described. 
Station 176, 1450 fathoms. — The sounding at this station seemed to indicate that 
there was a large amount of manganese in the deposit, associated with numerous fragments 
of pumice. Many of the Foraminifera were covered with minute grains of the peroxide 
of manganese, while others were filled and coated with a red-brown silicate, containing a 
considerable quantity of manganese. 
Station 181, 2440 fathoms; Station 184, 1400 fathoms. — The trawl brought up from 
these stations pumice stones similar to those described from Station 175, although the 
alteration in most ca.ses was not so far advanced. 
Station 213, 2050 fathoms. — There came up in the trawl several hardened pieces of 
mud or clay of a slate colour, in which were embedded pieces of wood. These hardened 
lumps were made up of the same materials as the deposit procured in the sounding tube, 
but were traversed by, and in some places coated with, deposits of manganese ; apparently 
the lumps came from a deeper layer than that usually procured in the sounding tube. 
The trawl may have dragged them up along with the remains of a water-logged tree. 
Station 215, 2550 fathoms. — The trawl contained several pumice stones coated with 
manganese, all of them less than 4 cm. in diameter. 
Station 216 a, 2000 fathoms. — A large number of pumice stones, varying from the 
