120 Horner's Geological Address. 



I shall content myself with stating some of the general re- 

 sults. On the Atlantic side of the Alleghanies, an area 

 about 400 miles long, from north to south, and varying in 

 breadth from 10 to 70 miles (with some detached patches 

 further south), is occupied at intervals by tertiary deposits, 

 which, in the intermediate spaces, are probably concealed by 

 the more modern deposits and alluvium which form the sur- 

 face. There are extensive tracts of Eocene formations, par- 

 ticularly in the south. Out of 125 species of shells which 

 Mr Lyell obtained from these deposits, he was not able to 

 indentify more than seven with species of the same epoch in 

 Europe. But there are a considerable number of represen- 

 tative species, and an equal number of forms peculiar to the 

 older tertiary strata of America. The Ostrea selloeformis 

 may be considered as representing the Ostrea flahellula of 

 the Paris and London basins, and appears to be one of the 

 most characteristic and widely disseminated Eocene shells in 

 this North American deposit. 



The Miocene deposits are of far greater extent than the 

 Eocene ; and there is in them a close affinity of many of the 

 most abundant species with mollusca now inhabiting the 

 American coast, the proportion being about one-sixth of the 

 whole, or about 17 per cent., in those examined by Mr Lyc^l, 

 who was able to identify 23 out of 147 with living shells. 

 The corals also agree generically with those of the Miocene 

 be Is of Europe ; the cetacea also agree generically, and the 

 fish in many cases specifically. 



Metamorphic Rocks. 



The theory of metamorphism, in its more extended appli- 

 cation, in recent times, to the explanation of the peculiar 

 structure of certain stratified rocks, has thrown a clear light 

 upon some of the most obscure and difficult parts of geology. 

 No geologist will now, I presume, hesitate to admit, that 

 there is evidence amounting to demonstration, that a perma- 

 nent source of heat exists in the interior of the earth, widely 

 spread beneath the stony envelopment, and that it has existed 

 at all times. Whether it is local or widely spread under the 

 surface — whether it is constantly maintained or is excited 



