BY HUGH MILLEE. 303 



the handiwork of man. The more durable beds, Hutton asserts, 

 will stand out from surrounding softer strata in shapes natural to 

 their structure ; much as a hard pebble stands out from the wast- 

 ing stone and lime of a timeworn edifice. JN'or does the title of 

 Hutton as the originator of the Atmospheric Theory of Escarp- 

 ments rest on a single sentence. ''Upon the principles of decay," 

 he says, "a horizontal bed of rock forms a table mountain; .... 

 an inclined rock of this kind forms a mountain sloping on the 

 one side and haying a precipice on the upper part of the other 

 side, with a slope of fallen earth at the bottom." 



Though little embellished by graces of style, this enunciation 

 is most distinct and precise. It is a notable instance of the pow- 

 erful sagacity that freed Hutton from what may be termed the 

 geological superstitions of his age ; and it is sufficiently curious 

 that while he is universally honoured as one of the Fathers of Geo- 

 logy, modern geologists should consider this theory as their own. 



In repudiating the Diluvial theory, long afterwards the favour- 

 ite one, Hutton was followed by his illustrator, Playfair, who, 

 in language at once masculine and elegant, controverted the no- 

 tion that any possible torrent could remove at a sweep ''bodies 

 of strata three hundred or four hundred feet, nay, even eight 

 hundred or a thousand feet in thickness." On the dipping side, 

 he said, these strata have the support of the neighbouring 

 rock ; at their broken edges of outcrop they lack it ; and ' ' be- 

 come a prey, therefore, more easily to the common causes of ero- 

 sion and waste on the upper side than on the lower."* 



Adequacy of this Agent. — There can be no doubt about the ade- 

 quacy of the wasting "influences of the atmosphere" to bring 

 about the required results upon a minzature scale. A model, with 

 sloping layers of wood and clay brought up to one level, would 

 soon be carved into a series of ruts and ridges by the elements. 

 But when the layers are many feet in thickness the ratio between 

 cause and effect seems altered. Let us give some consideration, 

 however, to the agents standing in the relation of cause. Two 

 factors are required : one, to h)0Rcn or disintegrate tlie rock 



♦IHualralions of the Iluttoiilan Theory, p. 403, 



