48 Dr Black on some appearances connected with the 



vation of these rocks, or more nearly preceded the diluvial 

 catastrophe, are questions not so easily determined. 



That a considerable refrigeration of the eartlfs surface in 

 these temperate latitudes took place after the deposit of the 

 carboniferous beds, there is every reason to infer from the 

 very diminished quantity of vegetable remains which are 

 formed in the succeeding strata of the new red sandstone and 

 lias, in which few types of the genera of the flora of the coal- 

 formation, and especially those of the more tropical character, 

 have been discovered. This great diminution or extinction of 

 these primeval plants, between the eras of the several deposits, 

 leads us to some great physical cause, such as a change of tem- 

 perature and climate, to account for this revolution in the ve- 

 getable world. 



That this climatorial temperature was, however, at one time 

 so far reduced, as not only to destroy the then existing race of 

 plants, but also to congeal the moist surface of the earth with a 

 crust of ice, is what we have no reasonable data for to advance. 

 If such had been the case in any remarkable degree, there 

 would very probably have been some evidence of this extent of 

 refrigeration having been discovered in some fragmentary and 

 shattered strata lying between the upper or superficial beds of 

 the carboniferous rocks, and the lower beds of the new red 

 sandstone deposit, but I am not aware that such enclosed re- 

 cords of congelation have been any where discovered. In 

 the absence of this evidence, we may venture to conclude, 

 that the refrigerating era of which we are in search, occurred 

 only while those portions of the laminated sandstones which 

 lie in elevated beds or outcrops remained exposed to the atmo- 

 sphere during the long periods of the many succeeding forma- 

 tions ; and consequently, this era was not only subsequent to, 

 but took place at some very remote period after the great 

 plateaux of our carboniferous rocks had been fractured and ob- 

 liquely elevated to the surface. In bringing down the period 

 of the congelation connected with our subject to a more re- 

 cent geological era, we are naturally led to enquire if there 

 are any appearances or fossil records in the more recent strata, 

 or on the surface of the earth, affording any corroboration of a 



