32 
sects the upper part of this valley ; and at the point where the two 
disturbances cross, considerable derangement of the strata is produced. 
In one quarry Mr. Sharpe noticed eight small faults, and the walls 
of the rocks on each side of the fissures had a beautiful polish. 
Though the author has adopted the term Hippurite limestone for 
this deposit, yet he did not discover any remains of that genus, but 
great abundance of spherulites, some of them probably of known 
species, and other fossils of the family of Rudista. He obtained 
also a considerable number of shells including Ezogyra flabellata, 
Pecien quadricostatus and Pecten striato-costatus. 
(e.) Red Sandstone.—This formation consists of various sands, 
sandstones, marls, and limestone, which are grouped by Mr. Sharpe 
in the following manner : 
Upper Division.—Ferruginous sands, sandstones, and coloured 
marls. 
Middle Division.—Calcareous sandstones and coarse limestones. 
Lowest Division.—Coarse sands, sandstones, and grits. 
The extent of country, composed of this formation, is very con- 
siderable. North of the Tagus, the red sandstone covers the greater 
portion of the area to the westward of the tertiary strata and Hip- 
purite limestone, the only tract belonging to other deposits being 
the hills at Cintra, and the lower ridges immediately surrounding 
them. A denuded strip of sandstone is also exposed between Loures 
and Cape Sinchette. South of the Tagus, the red sandstone forms 
a tract of variable breadth, extending from Palmella to the coast, a 
little north of Cape Espichel. The beds of this formation are greatly 
affected by faults and vary much in the angle of inclination, but the 
prevailing dip is towards the south-east throughout the districts on 
the Lisbon side of the Tagus. In the tract between Palmella and 
the coast, the strata have also been disturbed by considerable faults, 
but their usual dip is north, or north-west, at a high angle. Near 
Lisbon, the connexion of the red sandstone with the subjacent for- 
mations is not often exposed. North of Cintra the sandstone rests 
almost horizontally upon inclined strata of Espichel limestone, 
shale, San Pedro limestone and granite. South of the Cintra hills, 
it reposes very irregularly upon the Espichel limestone: and south 
of the Tagus, with every degree of want of conformity, upon the 
limestone of the Serra d’Arrabida (Espichel limestone); and in a 
great variety of positions upon the lofty peaks of the older red con- 
glomerate of the Cavoens and the Serra de San Luiz near St. Ubes. 
Lignite occurs im several places, and in sufficient quantities to have 
led to unsuccessful researches for coal. Sulphur also thickly en- 
crusts some of the sandstone strata; and gypsum has been worked 
near Santa Anna, south of the Tagus. Mr. Sharpe is of opinion, 
that the tepid springs of Estoril, near Cascaes, may derive their virtues 
from the sulphureous strata; and that the hot springs of Caldas 
da Rainha may owe their sulphureous qualities to similar strata. 
The only organic remains found in the sandstones, are vegetable 
impressions and seed-vessels ; but in the calcareous beds, corals and 
