1846 LETTER TO LYELL 91 



with which that country abounds were not produced 

 by any efforts of melted matter to escape, these efforts 

 being attended with the curved upheaval of different 

 parts of the strata where the efforts were made. I 

 wished to show that the curvatures were due to a more 

 universal action and a different power (see De la 

 Beche's Theoretical Researches ; I have not a copy 

 by me), viz. an effort of contraction in a solid crust to 

 accommodate itself by the force of gravitation to a 

 cooling and lessening internal mass. I never dreamed 

 of doubting that relief was obtained from the very 

 beginning of geological time by intermittent outpour- 

 ings of melted matter. On the contrary, I have got a 

 quantity of data together for future use respecting 

 remarkable periods when visible volcanic action more 

 or less obtained, and the efforts produced by this 

 action on the strata of the day ; but I shall also be 

 able to show that all these volcanoes were subsequently 

 affected equally with their associated strata by a power 

 stronger than they or than that which produced them. 

 You must not suppose that by such efforts I under- 

 stand a universal general crumpling at one time of 

 the whole earth's surface. There is perfect evidence 

 that the contrary was the case. It is not the accom- 

 modation of the melted matter I contend for, but the 

 accommodation of the solid circular external crust, 

 attempting to fit itself through the influence of gravita- 

 tion to a cooling and diminishing area within. 



Respecting the missing members of the New Red 

 Sandstone, I believe that they may exist, though 

 concealed by the Upper Series, it being remembered 

 that the New Red Sandstone lies as it were in a basin, 

 since we find that proceeding from north to south the 

 higher marls gradually encroach on and cover up the 



