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



entirely covered according to the above explanation. But it will be remembered, 

 that much of this lower deposit may have been washed away by superreninci 

 agents ; and indeed it is evident, from what was observed at Joppa, that the 

 boulder-clay did operate in this manner. 



2. The Boulder-Clay in different parts of the district, exists (as has been 

 previously mentioned) at the height of nearly .9G0 feet above the present level 

 of the sea. The body of water at the bottom of which this clay was deposited, 

 must have gi'eatly exceeded this depth. This inference would be warranted by 

 the single consideration of the weight and size of the boulders imbedded in the 

 clay ; — but it is still more forcibly suggested, by the fact, that some of the hills 

 over which these boulders were transported, are 1200 feet above the sea. 



That this body of water was, Avhen these boulders were transported, in a state 

 of violent and extensive movement, must be obvious even to the most superficia 

 observer. Some persons have endeavoured to account for the phenomena, by 

 supposing a wave or partial body of water to have passed over the country. But 

 it must have been a wave twenty or thirty miles long in one direction ; — for it is 

 one and the same deposit which is found on the coast of Fife, and in the county 

 of Mid-Lothian, both in its northern and its southern parts, and therefore must 

 have been one body of water which flowed over all that district. The force and 

 violence of the aqueous movement is demonstrated, by the enonnous quantity of 

 the materials transported by it, — by the fact of the clay in which they are imbed- 

 ded not exhibiting any laminae, — by the imbedded boulders not being arranged 

 according to size or weight, — by the rats or scratches both on these boulders and 

 on the subjacent rocks, — and by those deep excavations or scoopings in the rocks, 

 several of which I particularly described. That the same body of moving waters 

 which thus flowed over the district, extended to distant parts of the country, is far- 

 ther indicated by the character of the boulders, most of which are round-shaped 

 from having been rolled far, and many of which belong to rocks that do not occur 

 nearer than fifty miles. The circumstance last alluded to, shews also the direction 

 of the rush of waters. The mica-slate blocks must have come from the westward, 

 because it is only towards the west that this species of rock exists. This infer- 

 ence is confii-med by the ruts or scratches, which all lie in the same direction ; — 

 and it is confirmed by yet another circumstance. The place where the boulders 

 are largest, and where they exist in greatest abundance, is on the east side of the 

 hills, — as, for example, along the shore between Seafield and Joppa. The frag- 

 ments of rock there, are from ten to fifty tons in weight. They have evidently 

 rested there, in consequence of being sheltered by Arthur Seat, the Calton Hill, 

 and other roclvy eminences, from a western rush of waters. ' 



In the sandstone quarry at Joppa, may be seen a very striking proof, not 

 only of the violence which accompanied the transport of this boulder clay, but 

 also of the direction in which it went. It has been mentioned, that the edges of 



