286 AN ESTIMATE OF THE GEOLOGICAL AGE OF THE EARTH. 



stoneware, any alkaline reactions except the most feeble: ''Et incom- 

 parablement nioindre que celle qui se manifeste dans Feau distillee." 

 The presence of the chloride of sodium appeared to arrest the decompo- 

 sition/ To this inactive nature of sea water the prolonged preserva- 

 tion of feldspathic fragments on sea beaches has been ascribed. 



There is interesting evidence bearing in this direction to be derived 

 from the deep-sea deposits. The volcanic debris, whether wind or 

 water borne, must be in a line state of comminution in order to reach 

 the central oceanic deposits.^ Such particles must sink with extreme 

 slowness through depths measured by miles. Their subsequent sojourn 

 upon the bottom is of unknown duration. Yet it is remarkal)le that 

 when these deposits are analyzed the alkali ratio is that of the igneous, 

 not that of the sedimentaiy, rocks. This is a plain proof that the 

 waters of the ocean do not ati'ect them as would terrestrial rains and 

 rivers. 



Thus we find a deep-sea ooze from 5,422 meters deep between New 

 Zealand and Tahiti to contain 4.92 per cent of Na^O and 2.82 per cent 

 KgO. Another from a depth of 4,956 meters west of the Society 

 Islands gave 1.83 per cent Na^O and 1.74 per cent of KjO.^ In Mur- 

 ray and Renard's report of the CJiaUenger results, it is suggested that 

 some of this volcanic debris may come from submarine sources. In any 

 case the pumice and glass of the ocean floor, even when decomposed, 

 retain their igneous alkali ratio. Thus andesitic pumice contained 

 NagO 2.34, K^O 1.61 per cent; basaltic pumice, NagO 2.81 and K2O 1.24 

 per cent. Other concordant examples are given. 



Are we to make a correction for oceanic denudation ? Are the sol- 

 vent effects of a magnitude which would result in a noticeable fraction 

 of our estimate of geological time being in excess ? If we supposed 

 that the solvent effect of the waves acting on the full coast line of the 

 earth were not less, not even equal, but ten times as great as what is 

 continuously progressing in an equal area of the soils, the dispropor- 

 tionality of areas reduces its present solvent effects to one one-hundred 

 and seventy -seventh of the effectiveness of the land in suppl3dng solu- 

 ble materials to the sea. This would then be a correction of half a 

 million of years on the time estimate.* 



In the coastal effects of to-day this correction would be almost cer- 

 tainly excessive. To these effects must be added those progressing on 

 the immense quantities of fine silt which the rivers pour annually into 

 the oceans, and which has been estimated by Sir J. Murray as 2.5 

 cubic miles of sediment. Much of this rapidly finds a quiet resting 

 place, and probably nearly perfect preservation, near the coasts. The 

 remainder, bonie into deeper water, must yield something to the ocean. 



* Geologie Experimentale, I.p. 275. 



*See Wallace's Darwinism, p. 363, for facts as to these dimensions. 

 ^Rosenbusch, loc. cit., p. 420. 



* See also Island Life, p. 225, footnote, 



