36 
infers that the great mass of basalt was poured forth from fissures 
in the neighbourhood of Loures. 
The cliffs in the bay of Cascaes exhibit fine sections of basaltic 
dykes and disturbances; and on the beach west of Cezimbra masses 
of basalt are intruded into strata of red sandstone, which exhibit 
great marks of disturbance. ‘The Espichel limestone and the red 
sandstone have been also greatly elevated at the Castle Hill at Ce- 
zimbra, by a trap rock of which the date is uncertain. 
Although the author had innumerable opportunities of observing 
the junction of the basalt with the beds below it, yet in no instance 
did he observe any change in the characters of the subjacent rocks. 
The alteration produced in the beds of shale, which alternate with 
trap rocks near Cintra, has been already noticed. Mr. Sharpe con- 
siders these igneous strata to have been ejected contemporaneously 
with the deposition of the shale, and to be consequently older than 
the great coating of basalt. The Espichel limestone, in contact 
with the trap near Cezimbra, is also altered, being of a crystalline 
texture to a distance of fifty feet from the igneous rock. 
Granite is found only in the neighbourhood of Cintra, forming a 
range of hillsabout seven miles in length and fivein breadth. ‘Their 
greatest altitude is less than 2000 feet. The prevailing rock is a 
true granite consisting cf nearly equal proportions of quartz 
and felspar with a little mica; but towards the western end of the 
chain, syenite and porphyry occur. In the central portions of the 
hills, the granite is coarsely grained, and splits into large irregular 
blocks; but on the flanks it is schistose, finely grained, cleaves 
into rhombs, and might be mistaken for a sandstone. Veins of 
large-grained granite, however, occur in the schistose variety, and 
veins of finely-grained in the coarse central masses. 
Mr. Sharpe then describes, in detail, the dislocations in the sedi- 
mentary strata on the flanks of the granitic hilis; and he shows that 
all the formations, from the San Pedro limestone to the Espichel, 
have been dislocated, and thrown into highly inclined positions, but 
the details cannot be clearly understood without the aid of sections. 
It may however be stated, that in consequence of the red sandstone 
resting in nearly horizontai strata against the inclined beds of the 
lower formation, the latter was disturbed previously to the de- 
position of the sandstone, and that consequently the irruption of 
the granite of Cintra took place at a period anterior to the origin of 
the sandstone. 
Mr. Sharpe describes also with considerable minuteness the dis- 
turbance near Palmella, south of the Tagus; and he infers, from the 
relative position of the strata, that there have been, in that district, 
considerable elevations at four distinct periods. 
The paper concludes with some observations on the earthquake 
of 1755; and the author shows, that its effects were entirely 
confined to the tertiary strata, and were most violently felt on the 
blue clay belonging to the Almada beds, on which the lower part 
of the city is constructed. Not a building on the Hippurite lime- 
stone, or the basalt, was injured. 
