EEPORT OF MEETINGS FOR 1901 43 



wasted materials of that land to the sea-bottom, where the 

 mechanicallv-carried sediments were gradually spread out upon 

 the sea floor, layer after layer, the materials being coarser 

 or finer, accordingly as the currents varied in their carrying 

 powers. An extensive delta resulted from the gradual accu- 

 mulation of these sediments. Its seaward margin, during each 

 interval between the movements of subsidence, slowly, but 

 continually, advanced in the direction of deeper water. With 

 each of these downward movements the delta was lowered 

 beneath the waves ; and, as a consequence of this depression 

 of the delta, it happened many times that beds of limestone 

 and other rocks, formed by organico-chemical agency in clear 

 (and usually in deep) waters, were slowly built up over the 

 beds of mud, sand, and silt which, under shallower-water 

 conditions, had previously been laid down upon that spot. 



Along with the wasted materials derived from the rocks of 

 the old continent, the rivers transferred seaward the drifted 

 remains of the vegetation that had grown upon and near the 

 land ; and with these plants were transported representatives 

 also of the animal life which flourished in the same areas. 

 As the entombment of these organic lemains took place 

 beneath the water of the sea, there often occuned an inter- 

 mingling of forms of life proper to the land with those 

 belonging to the sea — the proportion of the one to the other 

 being dependent chiefly upon how far off the margin of the 

 land was for the time being. 



In the outline of the geological features given in the opening 

 sentences some reference was made to the presence here of 

 volcanic rocks. We need, therefore, to consider wliat relation 

 such materials of the Earth's crust bear to sediments, and 

 we should at the same time also enquire into the nature of 

 the causes to which volcanic phenomena in general are due. 

 As these points constitute an important feature in the present 

 case, it may be well to devote some of the following remarks 

 to its consideration. 



Amongst these questions one of the first importance i elates 

 to the geographical distribution of volcanoes, and their rela- 

 tion to some of the major features of surface relief. In 

 connection with this point we may first of all note that a 

 very close connection exists between areas of subsidence and 



