HISTORICAL SUMMARY. 3(55 



The event to which I allude is the little outburst of volcanic 

 activity at the time when these silts were being 

 Volcano of Loi Han accumu i ate( ] already referred to in the account 



Hun. ' J 



of the Man-sang coal-field (p. 313). It ex- 

 hibits, it is true, an extremely feeble manifestation of volcanic 

 energy, but it is interesting as the sole evidence of the presence 

 of these forces below the surface that we have met with in our 

 review of the whole sequence of fossiliferous rocks from lower 

 Ordovician to the present time. The situation of this little vol- 

 cano, at the very base of Loi Ling, the most highly elevated mass 

 of the ancient sea floor on which the fossiliferous series was de- 

 posited is, I am inclined to think, significant, as suggesting that if 

 we could probe to a sufficient depth, we would find that the under- 

 ground reservoirs of molten rock had been brought nearer to the 

 surface at this point than elsewhere ; and the particular time at 

 which the outburst occurred also suggests that one or other of the 

 great vertical faults played some part in opening a passage for the 

 emission of the lava. 



