35 
stratification may be studied to much advantage, as the whole measure is exhibi¬ 
ted on.the face of the mural escarpment, as it were, in miniature—none of the 
usual series being wanting. 
Across Brodich Bay the mountains exhibit a very different but less imposing 
aspect; and, instead of the serrated outlines we have just observed, they are seen 
rising in steps or stairs , and convey the best possible idea of the trap formations. 
They are composed mainly of phorphyry and greenstone. A fine-grained granite 
is also found here, and was first discovered by Mr. Ramsey, in 1837, and is be¬ 
lieved to be the very newest of the kind yet known. The reasons assigned by 
Mr. Ramsey for believing it to be the newest are, that no fragments of it are found 
in the neighboring rocks. It often sends veins into the slate, but, when raised to its 
present elevation, it could not have been in a state of fusion, from its being never 
found overlying the slate, which has evidently been fissured and partly elevated be¬ 
fore the deposition of the old red sandstone. It is also found penetrating the 
coarse granite, which is also traversed by dykes of porphyry and greenstone, while 
the fine granite is never thus penetrated; and indeed there is reason to believe that 
it is newer even than the traps with which it is found, and it also sends veins into 
the new red sandstone, which conclusively establishes its recent origin. The 
slates in its vicinity exhibit evidences of the action of fire, having been partially 
fused and the strata greatly disturbed. Sometimes they assume a granular ap¬ 
pearance similar to the true igneous intrusive rocks. 
Sailing south of Brodich Bay, some very beautiful and well-defined dykes of 
greenstone are seen, and also a remarkable pitchstone stratum, about 14 feet thick, 
which has been intruded horizontally between the old and the new sandstone. 
The . great importance of fossil remains , especially of fossil ichthyology , to 
identify formations locally remote from each other, was frequently insisted on by 
Mr. Murchison in the course of the day, and it seems to be a favorite proposition 
of his, to which I shall have occasion to refer hereafter. 
The scenery in the vicinity of Brodich Bay and “ Holy Island” (which is form¬ 
ed of trap resting on new red sandstone) is said to be not inferior to any other 
views in the highlands of Scotland, and repeatedly during the excursion called 
forth spontaneous exclamations of admiration from the party, as some new beauty 
in glen or mountain was discovered. 
At three o’clock we landed at Brodich Castle, under salutes of cannon from the 
shore and from the steamboats at anchor. At the wharf we were joined by Mon¬ 
sieur Agassiz, who had reached the island by some other conveyance. On land¬ 
ing, we were received by the Marquis of Douglass, as the representative of his 
father, the Duke of Hamilton, and were then marched up to the Castle, with the 
hereditary piper in full costume at our head, playing the Gathering of his Clan. 
At the Castle we sat down to a sumptuous entertainment, prepared by the Mar¬ 
quis for the refreshment of the company. During the repast many toasts were 
drunk, and several good speeches delivered. Among the best speakers was Dr. 
Buckland, who is a great gun, being Canon of Christ Church, Oxford. 
We left Brodich at six o’clock, on our return to Glasgow—every one apparent- 
