116 Mr. D. Sharpe on the Geology of 



Montachique ; and these thin out gradually to the westward, being replaced by the 

 upper beds at Pero Pinheiro, where the formation is of inconsiderable thickness, 

 and consists only of the latter. The large quarries at that village, which furnish 

 pretty, light-coloured marbles, are worked principally in the beds which contain 

 the Sphoerulites. Along this line there is a slight dip to the S.E, 



Another distinct range of Hippurite limestone begins on the south of Loures, 

 and reaches to the Bay of Cascaes. On the northern side it rests upon the red 

 sandstone, and upon the south and east is overlaid by basalt. From Loures 

 to the west of Bellas the beds dip S.E. at an angle varying from 30° to 50°, but 

 between Cacera and the coast, the inclination is usually less considerable, and in 

 the sea-cliffs the beds are nearly horizontal. Between Loures and Bellas, the mid- 

 dle and lower parts of the formation are exposed ; about Cacem the middle, and 

 near the coast the upper beds. The usual conformity between the Hippurite lime- 

 stone and the red sandstone does not hold good throughout this range, for, to- 

 wards Cascaes, nearly horizontal beds of the limestone rest upon inclined strata 

 of the sandstone ; still the direction of the dip of the two formations is the same. 

 (PI. XV. Sect. 7.) The limestone range widens out very much at its southern 

 extremity ; the basalt capping its higher hills. 



The narrow valley of Alcantara, on the w^est side of Lisbon, is the line of a 

 considerable fault which has raised to view the Hippurite limestone : the beds on 

 the two sides of the valley correspond in altitude, but dip from the valley in op- 

 posite directions, on the west side at 15°, on the east at 10°. An anticlinal line of 

 more violent disturbance crosses the former from Campolide to Mon Santo, and it 

 is to this cause that Mon Santo owes its elevation. Where the two faults cross, the 

 rocks are very much fissured and disturbed, and great landslips have taken place. 

 In one quarry I noticed six or eight faults, where the sides of the tissures had been 

 rubbed to a beautiful polish. This spot is called Terremotos, and the disturbance 

 of the rocks is frequently attributed to the great earthquake, but all the contem- 

 porary accounts of that catastrophe state, that this neighbourhood suffered very 

 slightly. 



Organic Remains. — Among the fossils of this formation are the following : — 



Exogyra plicata, Goldfuss, 82, f. 5, a shell found in the chalk in France and Belgium ; it occurs also 

 in the Espichel limestone (See p. 121.) 



conica ? Min. Conch., a very imperfect specimen. 



Pecten quadricostatus, Min. Conch., 56, f. 1 and 2, common in the upper and lower green sand in 

 England, &c. 



striato-costatus, Goldfuss, 93, f. 2, found in the upper chalk in Germany. 



Nerinea Borsonii, Bronn, an internal cast. 



nodosa ? Voltz, an internal cast, apparently of this species, which has been found in the coral 



rag. t 



