ANNIVERSARY ADDRESS OF THE PRESIDENT. Ivii 



of animal and vegetable life as geological time rolled on and the sur- 

 face of our planet became modified in various ways, than by forcing 

 local classifications beyond their worth, or by merely taking one part 

 of the evidence without the other, as has been too frequently done. 



In a memoir on the geology of the neighbourhood of Oporto, in- 

 cluding the Silurian coal of Vallongo, Mr. Sharpe furnished us with a 

 detailed account of apart of Portugal, of which, in 1832, he presented 

 a brief notice to this Society. After mention of the crystalline rocks 

 near Oporto, his section showing the granite of Oporto covered on the 

 W.S.W. and E.N.E. by gneiss, micaceous schist and chloritic schist, 

 he describes a band of rocks, chiefly formed of clay- slates, resting upon 

 the eastern flank of the latter, and which, from the character of the 

 organic remains obtained from it, he refers to the Lower Silurian 

 deposits. The lowest part of this series is remarkable for containing 

 several beds of anthracite, worked at San Pedro da Cora, eight miles 

 E.N.E. from Oporto. Mr. Sharpe states that the section is clear, 

 and that these lower beds, which repose on chloritic schist, evidently 

 dip beneath deposits containing Lower Silurian fossils. The upper 

 part of the group is formed of a thick accumulation of micaceous 

 sandstone, usually yellow, with some grey carbonaceous sandstone 

 near the bottom. This rests on a black carbonaceous slate, among 

 which are bands of indurated ferruginous clay, passing into clay iron- 

 stone. Beneath this comes a dark grey or black hard clay-slate, 

 with softer chloritic beds of a pink or yellow colour in the lower part. 

 Notwithstanding its contortion, this slate series is considered to have 

 considerable thickness. The lower beds of the dark grey slates, and 

 those lighter coloured and softer at the base of the series, are rich in 

 organic remains {Calymene, Ogygia, Isotelus, Illcenus, Chirurus, 

 Beyrichia, Orthis, Orthoceras, Bellerophon, Graptolithus, and 

 others), possessing a character from which Mr. Sharpe refers these 

 deposits to the Lower Silurian period. 



Beneath these strata, in descending order, the carboniferous accu- 

 mulations of San Pedro da Cora occur, gradually passing into the 

 beds above them. These carboniferous beds consist in descending 

 order of {a) red sandstone, {b) coarse conglomerates alternating with 

 black carbonaceous shales, (c) coal, 6 feet thick, (d) coarse micaceous 

 conglomerate, alternating with black carbonaceous shales, (e) coal, 

 thin bed, (/") coarse carbonaceous conglomerate, {g) coal, four beds, 

 from 2 to 5 feet thick, variable however in thickness in diiferent 

 places, the beds separated from each other by 3 or 4 feet of black 

 shale, and resting on black shale, and (h) slates apparently composed 

 of the debris of the chloritic schists on which they rest. The carbo- 

 naceous series is estimated at from 1000 to 1500 feet thick, and is seen 

 on the north bank of the Douro, at Jeremunde, twelve miles from 

 Oporto. North of San Pedro da Cora this series rapidly thins away, 

 and disappears about a mile and a half from that place. 



Having given a detailed account of the rocks referable to the Si- 

 lurian series, noticed by him in Portugal, Mr. Sharpe refers to the 

 beds described by Dr. Rebello de Carvalha as forming the chain of 

 the Serra de Marao, near Amarante ; those mentioned by M. Schulz 



