ANNIVERSARY ADDRESS OF THE PRESIDENT. llli 



as they do divisions in the accumnlations of a j)articular geological 

 time, which Sir Roderick Murchison considers it is desirable to esta- 

 blish, from his researches in Russia and elsewhere, in Europe. 



We are indebted to our Secretary, Mr. Carrick Moore, for an 

 account of some fossiliferous beds in the Silurian rocks of Wigton- 

 shire and Ayrshire, in which, after alluding to the labours of 

 Mr. Nicol, and stating that in the main the description given of 

 Peebleshire by Mr. Nicol is ajiplicable to Wigtonshire and the south 

 of Ayrshire, he mentions that the rocks consist of coarse and thin- 

 bedded greywacke, clay-slate in which true slaty cleavage cannot be 

 detected, and igneous rocks, in Wigtonshire " usually felspathic, 

 varying from a nearly pure felspar rock to a syenite." Though the 

 igneous masses appear to follow the range of, and be interstratified 

 with, the sedimentary accumulations with which they are associated, 

 our colleague considers the coast sections as showing that when the 

 igneous beds are properly traced, they can be seen to cut the sedi- 

 mentary rocks, generally afterwards, nevertheless, resuming their 

 course with them. It is also remarked that these latter are altered 

 at the contact, becoming more or less porphyritic, dark shales changed 

 to white, and sometimes to red ; and these effects observable on both 

 sides of the dykes. 



Mr. Carrick Moore then describes in detail the section exhibited 

 along the Irish Sea from the Mull of Galloway to Corswall Point. 

 He mentions a patch of granite near Dunman Hill, not previously 

 noticed, as worthy of attention from its being the only piece hitherto 

 observed on the surface between the granite of Carnsmuir on the 

 Cree, Kirkcudbrightshire, and that of the Morne Mountains, in 

 Ireland. A mass of syenite at Cairngarroch alters the adjoining 

 sedimentary rocks, and dykes of it are seen to cut them. Black 

 slates full of graptolites are mentioned at Morroch Bay ; slaty shales 

 and flags contain graptolites at Porto Bello Bay, and these fossils also 

 occur in a red flag or tilestone at Dally Bay, and in the continuation 

 of the same range of rocks at the Cairn. A limestone in the valley of 

 the Stincher afforded fossils, for the most part ill-preserved and not 

 numerous. Orthides however are well-preserved, and they were 

 abundant at Knockdolian. 



It may be scarcely necessary to allude to the value of the organic 

 remains thus obtained by Mr. Carrick Moore, and the aid they 

 afford towards a good understanding of the geological age of the 

 beds in which they are found. Mr. Salter, who examined the col- 

 lection, obtained from the limestones of the Stincher river and the 

 slates of Loch Ryan, considers that these beds may be referred to 

 the age of the Lower Silurian rocks. 



One of those conglomerates which may mark shores at this period, 

 or at all events conditions under which water-action could round and 

 transport pebbles and portions of rock having considerable size, is 

 noticed as occurring near the Corswall Lighthouse. The boulders 

 are sometimes as much as three, four, and even five feet in diameter, 

 showing the effects of no slight abrading force. Among the pebbles 

 and boulders, chiefly consisting of red quartziferous porphyry and 



