34 
Coarser crystalline marble, usually gray, but towards 
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. 
(i.) Older Red Conglomerate.—This formation occurs only west 
of St. Ubes; and though Mr. Sharpe describes it the last of the 
sedimentary series, yet he is not certain respecting its relative geo- 
logical antiquity. Near St. Ubesit 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 imbedded 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 Vigo, 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 30° 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 of 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 sufficient 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, Lorca 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 tv the family of Rudista, 
and considered the representative of the chalk and greensand series 
of England and the north of France. 
