108 



SUPPOSED FORMEE INTENSITY 



[Ch. VI. 



the 



of every destroying cause to obliterate the signs of its own 

 agency ; but the amount of reproduction in the form of sedi- 



must always afford 



measure 



minimum 



'•one. 



more than a minimum 



of the earth's crust in a multitude of cases have been 

 broken up again and again and re-stratified, so that it is only 

 the last of many forms through which they have past that is 

 now presented to our view. 



Erratics and ice-action. 



momenon 



advocates of the excessive power of running water in times 



enormous 



erratic, which lie scattered over the northern parts of Europe 



Unquestionably a large proportion of 



North America 



these blocks have been 



from 



them 



not unfrequently, deep seas and valleys intervening, or hills 



than a thousand feet high. To explain the present situa- 



more 



ments, a deluere of mud 



some 



come from 



of tons in weight. 



the north, bearing along with 

 stony fragments, some of them hundreds 

 This flood, in its transient passage over 

 the continents, dispersed the boulders irregularly over hill, 

 valley, and plain ; or forced them along over a surface of 

 hard rock, so as to polish it and leave it indented with paral- 

 lel scratches and grooves, — such markings as are still visible 

 in the rocks of Scandinavia, Scotland, Canada, and many 

 other countries. 



There can be no doubt that the myriads of angular and 

 rounded blocks above alluded to, cannot have been borne 



marine 



ume 



and weight, and so clear are the signs, in many 

 places, of time having been occupied in their successive 

 deposition ; for while some of them are buried in mud and 

 sand, others are distributed at various depths through heaps 

 of regularly stratified sand and gravel. No waves of the sea 

 raised by earthquakes, nor the bursting of lakes dammed up 

 for a time by landslips or by avalanches of snow, can account 







