EXCURSIONS. 
235 
When it is stated that Dr. Wheelton Hind was also present, 
it will not be a matter of surprise that the Excursion was one 
of the most successful ever held by the Society. 
The party left Douglas on Friday morning by train for 
Ballasalla and walked to the coast at Derby Haven. 
On the road, boulders of Foxdale Granite were found. These 
have been distributed to the south and west of the outcrop, 
which occurs in the centre of the Island, by glacial action. They 
have also been carried by the ice to the summit of S. Barrule, 
at an elevation of 700-800 feet above the highest point of the 
parent rock. This is one of the best examples of uplift by glacial 
action in the British Isles. 
The first exposure examined on the coast was one of Car- 
boniferous Limestone, the horizon being about 200 feet above 
the base of that formation. Numerous fossils were collected, 
with a view to comparing the horizon of these rocks with those of 
the mainland. Proceeding along the beach, a small fault was 
crossed and the basement conglomerate of the Carboniferous 
Series was examined. It consists of a red calcareous matrix, with 
pebbles of qua^rtz and slate and a few of the d3'ke materials 
from the Slate Series. 
The beds of the Carboniferous Limestone were then crossed 
in ascending order, and the members proceeded to Langness, 
where exposures of the Manx Slate Series were examined. 
A move was then made to Fort Island, where the Manx 
Slates were seen to be penetrated by two series of igneous dykes. 
The older set was injected prior to the great earth movements 
which produced the crumpling of the Manx Slates, since the dykes 
are sheared in the same manner as the slates. The later series 
of dykes (probably of Tertiary Age) cuts the older series and is 
not sheared. 
On the Castletown side of Langness a series of natural 
arches has been produced by the action of the sea. 
The tops of the arches consist of the basal conglomerate 
of the Carboniferous Series, while the sides consist of the Manx 
Slates (see PI.. XVII.). 
The Manx Slates formed an island in the Carboniferous 
Sea as they do now in the Irish Sea, and the shingle beaclies 
G 
