Geological Society- Sll 



The only organic remains found in the sandstones, are vegetable 

 impressions and seed-vessels ; but in the calcareous beds, corals and 

 shells occur, and Mr. Sharpe has been able to identify some of the 

 latter with the Perna rugosa, Trigonia Uterata and Terebratula in- 

 termedia, of the English secondary oolitic series. 



(_/".) Espichel Limestone. — This formation constitutes the flat, outer 

 band which encircles the Cintra hills, also the range of hills be- 

 tween Cape Espichel and Cezimbra, and most probabty the Serra 

 d' Arrabida near St. Ubes. At the first of these localities, it consists 

 of thick beds of gray coarse limestone, alternating with thinner ones 

 of shale or marl ; at the second, of a similar limestone with fewer 

 layers of shale ; and at the Serra d' Arrabida, of compact gray lime- 

 stone with no partings of shale, except towards the bottom of the 

 formation. Around the hills of Cintra, the strata dip as from a 

 centre, at angles varying from 20° to 75° ; between Cape Espichel 

 and Cezimbra their inclination is from 45° to 70° to the north ; and 

 in the Serra d' Arrabida the prevailing dip is also to the north at a high 

 angle, but at the west end of the Serra it varies from north to north- 

 west and north-east ; whilst in the northern side of the Serra de 

 Vizo, or the eastern prolongation of the Serra d' Arrabida, the dip 

 is toward the south. In the Cintra district the limestone rests con- 

 formably on the subjacent formation of shale ; between Cape Espi- 

 chel and Cezimbra, and in the Serra d'Arrabida the bottom beds 

 are not exposed, and consequently the connexion with the inferior de- 

 posits is not visible ; but in the Serra de Vizo the limestone reposes 

 quite unconformably upon highly inclined strata of the older red con- 

 glomerate. The organic remains of this formation are principally 

 casts of shells.which are not easily separable from the matrix. One of 

 the specimens obtained by Mr. Sharpe closely resembles a Trigonia 

 from the green sand of Blackdown. 



(g.) Shale. — The upper portion of this deposit consists princi- 

 pally of shale, vaiying a good deal in character ; the middle of 

 indurated shale alternating regularly and conformably with beds 

 of trap from five to twenty feet thick, and the lowest of dark shale. 

 Near Ramalhao, where the formation is best displaj^ed, there are 

 from twenty to thirty distinct alternations of igneous rocks and shale, 

 the latter being altered and indurated ; but in the cliff at the Praia de 

 Adraga, where the deposit is diminished to about 200 feet, there is 

 only one bed of igneous origin. The formation rests with perfect 

 conformity on the San Pedro limestone, dipping on all sides from the 

 central granite axis of Cintra, at angles from 30° to 60°. 



(h.) T/ie Sun Pedro Limestone forms an inner zone around the 

 Cintra hills, resting upon the granite. The upper beds are dark 

 gray and earthy ; but as the limestone approaches the granite, 

 it gradually passes into a crystalline marble. At the village of 

 San Pedro the following series is exposed : — 



Dark gray compact limestone several hundred feet 



thick. 

 Gray limestone with very slight traces of crystalline 



texture, and towards the bottom granular 200 feet 



Coarse crystalline marl>lc, white or gray and white 100 



