MR MILNE ON THE MID-LOTHIAN AND EAST-LOTHIAN COAL-FIELDS. 3II 



direction is W|S. A great many boulders have been lately dug out of this depo- 

 sit, in the excavations for the Newhaven and Edinburgh Railway. The direction 

 of the scratches on them is W^N. 



It is hardly necessary to observe, that these boulders belong chiefly to rocks 

 which, with one exception, exist only in very distant parts of Scotland. The 

 Greenstone boulders, of course, may have been derived from the trap hills in the 

 vicinity of Edinburgh, — though more probably from the Ochil range. From this 

 quarter also, most probably, the coarse conglomerate boulders have come. The 

 pebbles in this conglomerate consist of Greywacke, Quartz-rock, Lydian-stone, 

 and Felspar. One of these boulders, taken out of the clay at Joppa, is now lying 

 in front of Mr Grieve' s house, in Grove Street, Musselburgh. It is hardly neces- 

 sary to add, that the granitic and mica-slate boulders must have been likewise 

 transported from the west. 



This lower deposit of hard coarse clay which I have been describing, covers a 

 very large extent of country. Along the southern shore of the Firth of Forth, I 

 have traced it from the river Cramond to near Prestonpans. It is visible at a great 

 many points along this shore, — as, for example, at the mouth of the Cramond, 

 where it forms the east bank of the river, — to the east of Caroline Park, where it 

 was cut through in forming the new road to Granton Harbour, — at Newhaven, 

 where it is cut for the railway, — at Seafield, and at Joppa-pans, at both of which 

 places it is exposed by the ocean. But whilst visible only at the places now men- 

 tioned, there is no doubt that this boulder-clay forms a continuous bed from 

 Cramond to Magdalen Bridge. At Leith, in boring for Avater, it was penetrated 

 to the depth of 80 feet. The whole of the shore between these points is seen at 

 low- water strewed with immense quantities of rounded blocks, which, by the cliff 

 becoming undermined, have fallen out of the clay on the beach, and remain there 

 unmoved by the recurring tides, and by the waves or even the storms of the 

 ocean, — thereby testifying the prodigious force of the agent which was able to 

 transport them from their native sites. 



This same deposit of clay may be seen at other points along the coast, though 

 unpossessed of the large boulders just alluded to. It is this clay, I think, which 

 is worked at the brick-fields situated at Drumore gate, and at Prestongrange. 

 It is a coarse gritty clay, having interspersed through it small pebbles, and occa- 

 sionally a few thin seams of gravel. It is there about 18 feet thick. 



In describing the previous deposit, I mentioned that, at Joppa, near the shore, 

 this boulder-clay is separated from the rocks by a layer of sand. At Joppa quarry, 

 nothing intervenes between it and the rocks. If there had been any older super- 

 ficial deposit there, it must have been washed away by the boulder-clay ; for it is 

 seen in this quarry covering the edges of the strata, and forming a bed about 8 

 feet thick. 



With regard to the extension of this lower boulder-clay to the south, and 

 through the interior of the country, it is of course impossible to speak with the 



