100 



NOTES ON THE GEOLOGY OF DUNBAR SHORE. 



barrier. From this hollow, when you come near to the town, the ascent is 

 somewhat abrupt, for the situation of Dunbar is high and commanding. From 

 this point of view, as well as from the shore to the south, it presents a fine 

 appearance. 



The forenoon of the same day we devoted to an examination of the rocks 

 at the harbour and castle. 



The new harbour of Dunbar is formed by connecting the shore with an 

 outlying basaltic mass, the site of the battery, and further connectfng that 

 mass of rock by a pier and sea wall with the Trap rocks, on which are the 

 ruins of the old castle of Dunbar. These rise vertically through the strata 

 of Sandstone, which at the point of contact are highly indurated: portions of 

 it are enclosed in the Trap. Mr. Cunningham* says, "That the Trap on which 

 the castle of Dunbar is built, differs in different parts; in some places being 

 composed of Red Basaltic Greenstone, and in others of Tufa; and in one place 

 where the sea has formed an arch, masses of indurated Sandstone of many 

 yards extent, are entangled in the Trap rock." Professor Jamieson says, 

 "They are composed of Red-coloured Trap-tuff, Amygdaloid, and of a basalt 

 which contains Red Diallage and Olivnie, which, by the action of the weather, 

 has acquired a red colour. They form one inclined bed of great thickness, 

 which rises above the lower superincumbent and subjacent Red Sandstone." 

 These cliffs, with their capping of ruins, are extremely picturesque: they run out 

 boldly to some distance. '^The softer rocks," says the Rev. Mr. Jeffrey, ^'have 

 yielded to the perpetual motion of the waters, while the more compact remain; 

 forming large caverns, and rugged arches, through which the tide' rvishes with 

 impetuous fury; presenting a grand spectacle at all times, but awfully sublime 

 during a storm." The entrance to the new harbour has been cut right through 

 these rocks, detracting much from their interest, so far as the picturesque is 

 concerned; but thereby a fine section of the mass has been laid bare. It is 

 rent into chasms in various places, and some of the smaller veins are filled 

 with crystals of quartz and other minerals. 



The greatest point of attraction, however, will be found at the battery, 

 where the basalt assumes a beautifully columnar form. This was very finely 

 seen previous to the commencement of the new harbour operations. The islet 

 then presented the appearance exhibited in the annexed illustration. 



