212 
Proceedings of the Royal Society 
\.~BOULDEliS ON EIGG, AS DESCRIBED IN LETTERS TO THE 
CONVENER, FROM NORMAN MACPHERSON, ESQ., PRO- 
PRIETOR OF THE ISLAND. 
1. Rocks seen on the Surface. 
1. The S.W. part of the island has on it the remarkahle ridge of 
Pitchstone Porphyry, described by Professor Geikie and others, called 
Scoor-Eigg. The length of the ridge is altogether about two miles. 
It reaches at its east extremity to a height of about 1300 feet above 
the sea, at its west extremity to a height of from 900 to 990 feet. 
It rises from a plateau, which is about 400 feet above the sea. 
Its eastern half runs about E. and W., its western half N.N.W. 
and N.W. 
Both north and south sides are precipitous, almost vertical, show- 
ing on the north a cliff 270 feet, and on the south a cliff 400 feet in 
height. 
2. The north part of the island, it is believed, consists of bedded 
basaltic rock, but, being well covered by grass and moss, the rocks 
are nowhere visible. The island at its IST.E. end rises to a Height of 
about 1080 feet above the sea. At its northernmost extremity it is 
990 feet above the sea. 
The top of the hill is a smooth plateau, about half a mile broad, 
from which there is a precipitous dip towards the sea, on the N. and 
E. It is also precipitous towards a flat basin or hollow on the 
west, about 180 feet above the sea. 
In this basin sandstone and limestone rocks, of the oolitic age 
make their appearance. 
2. Old {cLEparently) Sea-Beaches. 
These occur at two spots, one in the S.E. corner of the island, 
at a height of about 60 feet above the sea, — the other on the JST.W. 
end of the island, about 100 feet above the sea. They consist of 
pebbles of rolled gravel, mostly half inch to three inches in length 
closely compacted. 
Except where these beaches occur, there are no gravel beds known 
on the island.* 
* Note by the Convener. — In the 6-incli Ordnance Survey map of Rum, two 
“gravel pits” are indicated as existing in the N.E. part of the island at a 
height of about 200 feet above the sea. 
