3\*2 Geological Society. 



Coarser crystalline marble, usually gray, but toward* 



the bottom bluish white, and still coarser 100 feet. 



Granite. 



The same gradual change may be traced all around the Cintra 

 hills, wherever the limestone can be seen resting upon or approach- 

 ing the granite. The lines of stratification are scarcely affected by 

 the change in the structure of the stone, and the dip is from the 

 granite at angles between 40° and 70°. Imperfect casts of a 

 bivalve and an univalve were found in this limestone by the author. 



(j.) Older Red Cunglomerate. — This formation occurs only west 

 of St. Ubes ; and though Mr. Sliarpe describes it the last of the 

 sedimentary series, yet he is not certain respecting its relative geolo- 

 gical antiquity. Near St. Ubes it rises from beneath the red sand- 

 stone and the Espichel limestone, and it is therefore older than 

 either of those rocks. The conglomerate consists of rounded peb- 

 bles of white or ferruginous quartz, with a few of jasper, mica slate, 

 and limestone. They vary from half an inch to more than a foot in 

 diameter, and are firmly embedded in a coarse ferruginous sandstone. 

 The highest ridge of the Serra de Covoens consists of this forma- 

 tion, also the eastern end of the Serra de San Luiz, the higher 

 parts of the Serra de A'igo, and the coast from St. Ubes to the foot 

 of the Serra d' Arrabida. At the eastern end of the Serra de Co- 

 voens and in the Serra de San Luiz, the dip of the beds is to the 

 north, at angles varying from oO° to 50° ; at the eastern end of the 

 Serra de Vigo they incline about 30° to the south ; more to the west- 

 ward, in the same serra, they are in some places vertical, in others 

 they dip about 50° to the north ; and at the Torre de Outao, at the 

 foot of the Serra d' Arrabida, they are inclined about 70° north-east. 



The description cf the sedimentary rocks is followed by an 

 attempt to compare each formation with its probable equivalent in 

 other parts of Europe ; but as the Lisbon fossils have not yet been 

 examined with suflicient care, Mr. Sharpe does not venture to draw 

 any positive conclusions. 



Of the tertiary series, the Almada beds alone offer any terms of 

 comparison, and these are not very satisfactory. The fossils col- 

 lected by the author are said to differ from those of the London 

 clay, with the exception of one species, which is considered iden- 

 tical with Natica similis ; but a long-hinged oyster, Ostrea longi- 

 rostris, abundant in the Almada beds, agrees with a fossil common 

 in the tertiary strata of Baza, Loi-ca and Alhama, in the south 

 of Spain, described by Brigadier Silvertop ; and Mr. Sharpe from an 

 examination of these deposits, as well as from the agreement in the 

 oyster, is induced to consider the Murcia and the Lisbon series as 

 of the same age. 



The Hippurite limestone, Mr. Sharpe has no doubt, is the equiva- 

 lent of the extensive formation in the south of Europe characterized 

 by the abundance of remains belonging to the family of Rudista, 

 and considered the representative of the chalk and greensand series 

 of England and the north of France. 



The red sandstone Mr. Sharpe considers to belong also to the 

 secondary system, in consequence of his having obtained from it 



