1817.] ' to the Giants Causeway. 121 
chisel. In other parts the columns are smaller, inclined, or bent; 
and a less length of them strikes the eye. From the bottom of this 
precipice issues, with a gentle slope of about 1 in 30 towards the 
sea, an immense and surprising pavement, as it were, consisting of 
the upper ends of the fragments of vertical columns of basalt that 
have been left when the seaward half of the basaltic hill was carried 
off. The ends of these columns are in general 15 or 20 inches in 
diameter, some of them of three sides, some four, five, six, seven, 
eight, or even nine. Five and six sides seem to prevail most. From 
the bottom of the precipice to the sea at low water along this pave- 
ment or causeway, which, from the artificial appearance it puts on, 
has, doubtless, in a rude age, given name to the place, is a length 
of 730 feet. It has been observed to proceed into the Ocean as far 
as can be traced by the eye ina calm and clear day. ‘To any person 
who has seen both this place and Staffa, the idea naturally enough 
suggests itself that they are parts of the same once continuous 
immense bed of columnar basalt. There are properly three pave- 
ments proceeding into the sea, distinguished by the names of the 
Great Causeway, the Middle Causeway, and the West Causeway. 
These are three large gently sloping ridges of the ends of basaltic 
columns, with depressions between them, covered with large blocks 
or masses, that seem to have from time to time been detached, and 
rolled from the precipice. I had no opportunity of perceiving with 
what rocks the basalt of the Giant’s Causeway is connected. Iam 
told conchoidal white lime-stone meets it on both the east and west 
sides. There is in one place near the east side of the Great Causeway 
a green-stone vein cight or ten feet wide intersecting the basalt 
from north-west to south-east. 
There was now pointed out to us by the guides a singular enough 
and curious phenomenon, and which is particularly interesting, as it 
has been thought by those who hold the igneous origin of basalt to 
bea confirmation of their doctrine. Nearly opposite to the West 
Causeway, and within about 80 feet of the top of the cliff, is found 
to exist a quantity of slags and ashes, unquestionably the production 
of fire. On ascending to this spot, which can be easily done, I 
found the slags and ashes deposited in a sort of lead about four feet 
thick, and running horizontally along the face of the basaltic pre- 
cipice 20 or 30 feet. The ashes are in general observed to lie 
undermost, and the slags above them. ‘They are covered with a 
considerable quantity of earth and stones, which all consist of 
basalt, are of a large size, some of them three or four feet or more 
in diameters and the ashes likewise rest on the same sort of mate- 
rials. What struck me here was, that these ashes and slags are 
entirely unconnected with any rock or formation which seems to be 
in situ, or in its original position. They are, therefore, in my 
opinion, distinctly artificial, and nothing more than the remains of 
some large and powerful fire which had been kept burning for a long 
while on the top of this precipice, either for the purpose of a signal, 
or some other which we cannot now ascertain ; and that, owing to 
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