16 



THE GEOLOGIST. 



thus lashed into fury by the winds, it may suffice to mention one fact, 

 which is not in itself devoid of geological interest, inasmuch as it 

 may serve to explain the occasional appearance of large blocks of 

 stone in unexpected localities. In passing along Broad Sound from 

 the south-east, there is an island called Great Crebawethan, which is 

 probably in some way more exposed than others to this oceanic force. 

 At any rate, there it is to be witnessed, standing probably eighteen 

 or more feet out of the surface of the deep, at the highest spring- 

 tides, with large boulders of granite, from half a ton to two tons 

 weight, heaped upon its surface, as though the ballast of a dozen 

 vessels had been discharged there by the hands of man, every 

 stone of which, as I was assured by Mr. E. Douglass, the intelligent 

 superintendent-engineer of the Bishop's Lighthouse works, has been 

 raised to its present position, and deposited there, by the force of 

 the waves.* The total destruction, too, of the iron lighthouse upon^ 

 the Bishop's Rock, which, when near completion, was instantaneously 

 uprooted, and dashed into the sea, on the night of February 5th, 

 1850, may serve to convey an impression of the violent force to 

 which the sides of the islands facing the Atlantic lie exposed ; and 

 this will explain how it is that, when viewed in this direction, they 

 appear rugged, precipitous, and excavated into caverns and gaps, while, 

 approached from the eastern side, they lie smiling in the sun like 

 fairy lands, or like the islands of the ^gean transplanted to our 

 hyperborean shores. 



As the geologic features of St. Mary's are more or less repro- 

 duced on a smaller scale in the other islands, I shall now proceed 

 to give a detailed account of its most important characteristics. It is 

 an irregular-shaped elliptical island, having two peninsulas attached, 

 one to the lower, or western, extremity — viz., the Hugh, now 

 fortified for a garrison, on the isthmus of which Hugh Town, the 

 capital of the Scilly Islands, is built ; and the other at the extreme 

 end, south of the island, terminating in the bold promontory of 

 Peninnis Head, which is surrounded by Path Cressa Bay, the Atlantic 

 Ocean, and Old Town Bay. The surface of the island is very various, 



* Mr. Douglass also informed me that, when lodging on Rosevear island, to 

 superintend the works connected with the Bishop Lighthouse, he had known 

 blocks of granite twenty tons in weight to be moved some distance by the sea. 



