198 NOTES ON THE GEOLOGY OF EAST LOTHIAN AND BEUWICKSHIRE. 



from the sheltered position it occupies between two lofty heads of land, the 

 sea having made a very deep indentation. The features of this spot are 

 highly interesting also, but as they are nearly those which I have already 

 described, I will not trouble you with a repetition; I Avould only notice that 

 there is another intrusion of trap, similar to that found at Dunbar, recognised here. 



We now wended our steps homewards, intending to return by the sea- 

 coast for the purpose of visiting the Pan Quarry, where, we were told, are 

 to be seen some fine specimens of fossil trees, but as we found ourselves 

 somewhat footsore," we thought it most prudent to go by the high road. 

 Having arrived at Dunbar, we visited again the raised beach, mentioned by 

 Mr. Robert Gray,'^ and we had the satisfaction of proving his statement with 

 regard to Helices being found in it, for we had not been many minutes at 

 work before I extracted a specimen of Helix nemoralis, evidently as old as 

 its associated shells. I mentioned this fact to our excellent Vice-President 

 on my return, and he informed me that he was not surprised at it, as Helices 

 frequently wander down to the shore. All the shells we found are those now 

 living on our coasts. 



By way of conclusion I may, I think, endeavour to relate as concisely as 

 possible the history of this coast, so far as I have had the means of exami- 

 nation, without being accused of an unreasonable spirit of hypothesis. 



1st. — A great physical group has been deposited in a region which is now 

 occupied by the line of coast, stretching from Siccar point to Coldingham 

 bay — the schists and clay slates of the Silurian age. 



2nd. — Afterwards came the period when the granitic axis was elevated. 

 When the elevatory movements began, and how long they were continued, I 

 do not think it is possible to determine; but they ended before the deposition 

 of the Old Red Sandstone; for before that period the granitic axis and the 

 Silurian masses had assumed their present relative position. I strongly suspect 

 that two large veins of granite must lie on either side of the contorted schists; 

 for in no other way can I explain the immense flexures, and the innumerable 

 quartz veins of all sizes which ramify them. Now, after the strata were thus 

 bent and contorted, let us suppose a denuding current to sweep away the 

 higher and more exposed portions, the strata would thin off, and present in 

 many places vertical columns, which they actually do. It is not assumed that 

 the disturbing action ceased at an epoch anterior to the deposition of the 

 unconformable Sandstones. On the contrary, there is no doubt that it continued 

 long afterwards, and that these beds have undergone fractures and dislocations 

 like the older strata, though to a smaller extent. In this way alone can I 

 account for the highly crystalline state of these sedimentary deposits. 



3rd. — After this, were deposited the conglomerates and finer Sandstones of 

 the Old Red, which range from Dunbar to Siccar point, and extend inland 

 across the whole country, with one or two breaks to Ayrshire, and a patch 

 beginning at Berwick upon-Tweed, crossing as far as Jedburgh and Selkirk. 



* Vid. Proceedings of Natural History Society of Glasgow, first fasciculus, page 6. 



