112 Horner's Geological Address. 



tremely obscure, and presents a wide and interesting field 

 for future investigation. Before concluding this part of my 

 subject, into which I shall probably be thought to have en- 

 tered at disproportionate length, I would call your attention 

 to some difficulties which the South Welch section offers to 

 the commonly-received and, I believe, well-founded opinion, 

 that anthracite is bituminous coal, the volatile parts of which 

 have been driven off by heat acting gradually from below ; 

 for we see (8 and 9) that thin seams of common coal are 

 interstratified with anthracitic seams and with anthracite. 

 Neither do we find any signs of metamorphic action in the 

 underclay in immediate contact with the coal, nor in the 

 strata thaiblie between two seams of anthracite. We must 

 look to the chemist to explain all this, as well as for en- 

 lightenment on the formation of the different qualities of 

 coal ; but we must be contented to receive from him only 

 indications and resemblances ; for we must never forget, 

 that, in our experiments, we can never have the volume of 

 materials, the amount of pressure, and above all, the dura- 

 tion of time with which Nature has worked ; and each of 

 these, singly and combined, must have had important influence 

 in modifying the results. 



Permian System. 



The soundness of the principles on which Sir R. Murchi- 

 son and M. de Verneuil first proposed to establish this great 

 division, has been confirmed by subsequent observations both 

 by themselves and by others, and appears to be recognised by 

 the geologists of all countries. The name of Permian, too, 

 has been as willingly adopted as that of Silurian was, being 

 at once convenient and appropriate, and recalling the locality 

 where a true type of the series can be referred to. In their 

 first journey to Russia, only a part of the region where these 

 rocks predominate was examined ; but they saw enough then 

 to satisfy them that some new classification was called for, 

 and Sir R. Murchison developed his views and those of his 

 associates at the meeting of the British Association at Glas- 

 gow in 1840, and in a paper read before this Society in the 

 following spring. In his address as president at our anni- 

 versary in 1842, he referred to his second journey in the 



