29 
Galloway, Mr. Lyell discovered distinct remains of Graptolites, re- 
sembling those found in the Silurian strataof England and Sweden. 
As Mr. Lyell is not aware of these zoophytes having been before 
observed in Scotland, and as organic remains are exceedingly rare 
in the great range of slaty sandstone and shale, which extends from 
St. Abb’s Head to Galloway, he considers the discovery of a fossil, 
affording a test of the relative age of those beds, not unimportant. 
The strata contaiing the Graptolites are nearly vertical, and their 
strike is west-south-west and east-north-east. 
Mr. Sharpe’s paper ‘‘ On the Geology of the Neighbourhood of 
Lisbon,” commenced at the meeting held on the 9th of January, was 
then concluded. 
In 1832, Mr. Sharpe laid before the Society, a short account of 
the geological structure of the neighbourhood of Lisbon* ; but having 
since that period resided for a considerable time in the same district, 
he gave in the paper read on the 23rd instant, the result of his more 
extended and matured acquaintance with the country. 
The tract described by Mr. Sharpe, is bounded towards the north 
by a line extending from Torres Vedras by Sobral to Villa Franca, 
and in the south by the coast from Cape Espichel to St. Ubes; and 
the whole of its area is about 650 square miles. 
The formations are arranged by the author in the following order, 
the local names having been taken from the points where the strata 
are best exhibited : 
Tertiary. (a.) Upper tertiary sand.—(6.) Almada beds.—(c.) Lower 
tertiary conglomerate. 
Secondary. (d.) Hippurite limestone.—(e.) Red sandstone.—(/.) 
Espichel limestone.—(y.) Slate clay and shale.-—(h.) San 
Pedro limestone.—(z.) Older red conglomerate. 
Igneous Rocks.—Basalt.— Granite. 
TERTIARY FORMATIONS. 
The tertiary deposits occupy a tract, only a portion of which is 
included within Mr. Sharpe’s district, as they extend in a north-east 
direction to Abrantes, a distance of eighty miles, and in a south-east to 
Alcacer do Sal, a distance of fifty miles. ‘The Tagus flows through 
the tract from Abrantes to the sea, but the greater part of the ter- 
tiary strata are situated to the south of the river.- 
(a.) Upper Tertiary Sand.—This formation consists of about 100 
feet of fine gray quartzose sand, and 150 feet of coarse quartzose 
ferruginous sand and gravel. It constitutes nearly the whole of the 
tertiary district, south of the Tagus, included within the author’s sur- 
vey. The strata are usually quite horizontal, except at the edges of 
the basin, where they rest upon the inclined beds of the subjacent 
deposits; and the author did not observe any instance of their 
having been disturbed. They generally repose upon the Almada 
limestone, but near Aldea do Meco, to the north of Cape Espichel, 
they are in contact with the red sandstone formation. No traces of 
* Proceedings, vol. i. p, 394. 
