1867.] Geology. 571 



formations of rocks to feel satisfied that there is no room for the 

 establishment of any new system of strata, such as the Silurian, the 

 Carboniferous, or the Triassic ; nor can we suppose that future 

 discovery will materially alter our views regarding the order of 

 succession of life on the globe. 



The business of the Section was opened by a very instructive 

 address from the President, Mr. A. Geikie, F.K.S., who, instead of 

 drawing up a discursive essay on the science of Geology in general, 

 limited his remarks — as we think wisely — to one special branch, to 

 which his own attention has been specially directed. The subject 

 chosen had reference to the successive periods in Geological time, 

 during which there are evidences of volcanic activity in the British 

 Islands. In this address the author showed " that from the massive 

 feldspathic lavas and ashes of the Lower Silurian rocks, up to the 

 great basaltic plateaux of Miocene age, most of our geological for- 

 mations contain somewhere evidences of contemporaneous volcanic 

 activity." Commencing with the sheets of felstone and tuff of the 

 Lower Silurian period in Wales, which were first described by 

 Sedgwick and Murchison, and have been mapped and described in 

 great detail by the Government Geological Surveyors, the author 

 gave a graphic sketch of the successive outbursts of volcanic activity 

 during the Upper Silurian, Old Eed Sandstone, Carboniferous, Per- 

 mian, Triassic, and Tertiary Periods. To the Miocene stage Mr. 

 Geikie refers the great trappean masses of Skye, the inner Hebrides, 

 and the north of Ireland, as well as the dykes which traverse some 

 of the rocks of the south-west of Scotland and the north of 

 England. This view, which is in opposition to that of the late 

 Professor E. Forbes, who referred them to the Oolitic period, 

 Mr. Geikie founds on the fact, amongst others, that in Mull, 

 masses of porphyritic and trachyte-like rocks, with a united thick- 

 ness of over 3,000 feet, overlie beds with plants of Miocene species. 

 Before passing on from the address, we are desirous of calling the 

 author's attention to two points with reference to the age of certain 

 outbursts of trap in England. Mr. Giekie may not be aware that 

 in Leicestershire there is an instance of an outflow of trap which in 

 all probability is referable to the Permian period. This rock occurs 

 as a sheet of greenstone overlying unconformably the Coal-measures, 

 and in turn overspread by Triassic strata, which are in no way 

 affected by it. As it seems to have been erupted at a period 

 between the Carboniferous and Triassic formations, it may be fairly 

 referred to the Permian age, and is perhaps a solitary instance of 

 contemporaneous trap of that period in England. 



The other fact is, the occurrence of a dyke of greenstone, 

 cutting through and indurating the New Bed Marl in North Staf- 

 fordshire. The knowledge of this case may induce him to modify 

 a statement in which he says, " I am not aware of any satisfactory 



