168 



APPENDIX. 



eventually came to rest as a layer of felspar on a Red Clay bottom. That the ash remained 

 suspended for some time in the sea before settling on the bottom is clear from the fact that 

 it carried down with it some shells of pelagic Foraminifera, which are now represented by 

 the casts above described. 



Secondary products as these zeolitic masses are, they are themselves destined to pass 

 into some more stable form of deposit. Their rarity in such bulk as at Station 2, their 

 porous consistency, and their sporadic occurrence preserved, like flies in amber, in man- 

 ganese nodules, testify to their decadent nature. Such a tuff as those here dealt with 

 doubtless formed, at one time, an extensive and continuous sheet, which was presently 

 broken up by movements of the earth's crust. As we now find it, it is well on its way, 

 under the chemical attack of sea-water and the boring operations of worms, to being 

 the surrounding Eed Clay. 



B. EED CLAY from Station 4719, 2285 fathoms. 



As pointed out in the concluding remarks, this deposit is abnormal in so far as it con- 

 tains no calcium carbonate, while at the adjacent stations, where the depth is only 100 

 fathoms less, the deposits contain over 50 per cent of calcium carbonate. 



The elementary particles of this deposit are comparatively large, translucent, gelatinous 

 flakes, which readily sink when suspended in water, whereas the fine opaque particles 

 of an argillaceous Red Clay of the Atlantic or North Pacific type, or ordinary terrestrial 

 clay, remain suspended for a long time. Under the microscope the gelatinous and semi- 

 transparent character of the deposit is still further brought out; the coloring-matter, so 

 far as it does not consist of occasional specks of manganese, seems to be dissolved rather 

 than disseminated in the substance, and varies in intensity from place to place, whence the 

 mottled look of the deposit. When nearly, but not quite, dried, the substance is intensely 

 slippery and unctuous to the touch, far more so than ordinary Red Clay. 



The deposit yields very readily to the attack of warm or even, on prolonged standing, 

 of cold dilute acid, an almost colorless flocculent residue being left behind. 



A chemical analysis of the deposit was made, and an extraction test was carried out by 



boiling up one gram three times with 50 cc. of j — n. hydrochloric acid and analyzing the 

 filtrate. The exti-action-residue consisted mainly of hydrated silica, with a little alumina, 

 iron, and manganese. 



The analytical figures for the deposit itself and for the extract, calculated to substance 

 dried at 110° C, are as folio us : — 



