Masterpieces of Science 



It is well known that the stream of the Missis- 

 sippi is charged with sediment of a different 

 colour from that of the Arkansas and Red Rivers, 

 which are tinged with red mud, derived from 

 rocks of porphyry and red gypseous clays in "the 

 far west. " The waters of the Uruguay, says 

 Darwin, draining a granitic country, are clear 

 and "black, those of the Parana, red. The mud 

 with which the Indus is loaded, says Burnes, is 

 of a clayey hue, that of the Chenab,onthe other 

 hand, is reddish, that of the Sutlej is more pale. 

 The same causes which make these several rivers, 

 sometimes situated at no great distance the one 

 from the other, to differ greatly in the character 

 of their sediment, will make the waters draining 

 the same country at different epochs, especially 

 before and after great revolutions in physical 

 geography, to be entirely dissimilar. It is 

 scarcely necessary to add that/ marine currents 

 will be affected in an analogous manner in con- 

 sequence of the formation of new shoals, the 

 emergence of new islands, the subsidence of others, 

 the gradual waste of neighbouring coasts, the 

 growth of new deltas, the increase of coral reefs, 

 volcanic eruptions, and other changes. 



UNIFORMITY OF CHANGE CONSIDERED, SECONDLY, 

 IN REFERENCE TO THE LIVING CREATION 



Secondly, in regard to the vicissitudes of the 



living creation, all are agreed that the successive 



groups of sedimentary strata found in the earth's 



crust are not only dissimilar in mineral composi- 



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