48 RELICS FROM THE WRECK 



in its present combination in the shape of shale, clay, 

 flags, or sandstone, has, in every instance, heen associated 

 with, or constituted entirely, the rocks that precede each 

 other in the series. 



These remarks raise several questions, each of which leads 

 us to draw largely upon time. Before the great conglom- 

 erate, the lowest member of the old red sandstone, was de- 

 posited, the pebbles of which it is principally composed must 

 have existed in the shape of quartz rock in beds or masses ; 

 and truly they must have occupied large areas of the sur- 

 face of the earth as it then was. These masses must have 

 been broken up into fragments of all sizes, probably by in- 

 ternal commotions, aided by the influence of water. 



The conglomerates deposited, we must find time for the 

 formation of the sandstone. The beds of this rock are often 

 very thick, and are exceedingly numerous. The matter 

 of which they are composed originally existed as rock, and 

 through long exposure to the atmosphere, the shoivers of 

 heaven, l/ie continuing" ripple of running water, and the 

 incessant beat of the ocean wave, it has been disengaged 

 from its original combinations, carried downward to the 

 ocean, and after being held for a time in mechanical or 

 chemical solution by the water, is- spread out upon its 

 bottom. This is not the work of a few years. But how 

 are the demands upon time increased, when we reflect that 

 rocks thus formed by slow degrees, are consolidated, heaved 

 upward, exposed to the elements, and by partial decay sup- 

 ply the material for beds higher in the series, and which 

 pass through the same tedious processes in their forma- 

 tion? 



Perhaps the immense beds of shale, and clay, that inter- 

 mingle with the harder rocks, required a period to accumu- 

 late, little short of that which must be granted to the sand- 

 stones. The material of which they are composed has also 

 been supplied by mechanical and chemical causes, and, in 



