102 NOTES ON THE CJEOLOOY OF DUNBAR SHORE. 



islets presents a striking analogy to those 'circles of volcanic rocks^ which are 

 so common among the coral-crowned islands of the Pacific. 



Passing eastward from the harbour and town of Dunbar, a series of fine 

 surface sections are obtained on the shore, between high and low water. 

 Immediately beyond the extreme verge of the tide, the ground rises abruptly, 

 and then retires with considerable diversity of hill and hollow towards the 

 interior. The abrupt declivity presents no view of the rocks, being covered 

 with a deep deposit of red clay, but along the shore we have a fine sequence 

 of the strata laid bare. 



For a considerable distance the explorer passes over a series of beds belonging 

 to the old Eed Sandstone group. Immediately at the back of the harbour, 

 we meet (as described by Professor Jamieson,) ^^with a red conglomerated 

 Sandstone, extending north-east and south-west, and dipping, like the Trap of 

 the harbour, to the south-east. It is succeeded by a bed of red-coloured Trap- 

 tufa, having the same direction and dip. The next bed is a conglomerated- 

 like Sandstone; it is of a reddish colour, and embedded in it are patches 

 and spots of a white-coloured Sandstone. A greenstone rock, partly porphyritic, 

 partly tufaceous follows. It is much intermixed with the red conglomerated 

 Sandstone, and is traversed by veins, several inches wide, of white quartzy 

 Sandstone." 



Beyond the cottages is a long level tract of Red Sandstone Rocks, with a 

 south-west and north-east direction, and dipping at about 20° east-south-east. 

 The inclination at first is very slight, and the edges of the strata run out 

 with a regularity which cannot fail to strike the explorer, especially if looked 

 down upon from the road on the high ground above. They look indeed like 

 the ridges of a ploughed field on a gigantic scale. The beds are thin, and 

 for the most part of a deep red colour. It is everywhere marked by circiilar 

 or oval spots, of a bright green colour, called by Professor Jamieson, moun- 

 tain green, or celandine. On examination, I found that the colours did not 

 go into the stone; a blow or two with the sharp edge of the hammer being 

 always sufficient to cut them out. In many places green-coloured clayey layers 

 are interstratified with the red sandy rock. 



As you pass eastward, the strata become still more inclined, then entirely 

 vertical. They lose their red colour, and assume a greyish tinge, and a 

 highly indurated appeara,nce; their jagged and serrated edges project in 

 confused variety of ruggedness. Immediately their dip is reversed, and they 

 are found lying against a dyke of Greenstone. This is immediately below 

 the west end of Broxmouth Park. The Greenstone dyke runs out a 

 considerable way into the sea, and its dark colour has obtained for it the 

 name of the Black Rocks. In its neighbourhood small veins may be noticed 

 running from it through the Sandstone. The following diagram represents 

 this section. Its position is marked on the Map by the letters A B. The 

 normal inclination of the strata is seen in the diagram, from a to /;. It 

 changes at c, the reversed direction being marked from c to <l; the strata 



