38 Anniversary Address of the 



cliffs close at hand. In Scotland, also, we see occasional 

 fragments of large dimensions in the conglomerates of the 

 old red sandstone, especially on the western coast, but in 

 that case there is no ground for presuming distant transport. 

 In no part of the geological series, except in that of very 

 modern date, do we find an extensive deposit of drift, like 

 that spread over Northern Europe and North America. 



It may doubtless be objected, that by adopting the glacial 

 hypothesis we concede the possibility of one natural agent, 

 such as frost, acquiring at certain periods an intensity of 

 action far greater than at others, and hence I may be asked, 

 whether the energy of any other cause may not in an equal 

 degree be subject to secular variation? I admit the force 

 of the argument, if not pushed beyond its legitimate bounds. 

 No one can contemplate future changes in physical geo- 

 graphy without foreseeing that the varying altitude and 

 extent of polar and equatorial lands may give rise to an 

 intensity of solar heat or glacial cold, such as is not ex- 

 perienced now, and may never have been experienced on the 

 earth ; for the combinations of circumstances on which the 

 climate of the globe most depend are so varied, that no one 

 can define or guess how far heat, cold, moisture, and other 

 conditions, may deviate from a mean state of things in the 

 course of ages. But speculations of this kind belong equally 

 to the future, the past and the present, and imply no incon- 

 stancy in the general condition of our planet, such as is 

 assumed in the hypothesis of its passage from a chaotic to a 

 fixed, stable, and perfect state. Living as we do in an era 

 which has immediately followed the glacial epoch, we are 

 able to comprehend the state of the northern hemisphere in 

 European latitudes, when cold like that of the arctic and 

 antarctic circles extended further from the poles towards the 

 equator. We may also reason philosophically on the state 

 of the globe during the carboniferous epoch, when there may 

 have been little or no ice even at the poles. We may con- 

 clude that in those days a warmer, damper, and more uni- 

 form climate prevailed, when the Sigillaria, Lepidodendron, 

 Caulopteris, Calamite, and other fossil plants flourished, and 

 when there were reefs of coral in the adjoining seas. Such 

 organic remains may betoken, as our Foreign Secretary, Mr 



