MB MILNE ON THE MID-LOTHIAN AND EAST-LOTHIAN COAL-FIELDS. 313 



be traced up to within a few hundred yards of the Edinburgh road. At the 

 point where it stops, it is about 700 feet above the sea. 



This boulder-clay extends into East-Lothian, and may be seen in different 

 parts of the Tyne valley ; as, for example, at Ormiston and Yester. At West 

 Garlton, about 1^ miles north from Haddington, there is a bed of clay which has 

 been worked for bricks. The upper and workable part is eight feet thick. I 

 rather think it belongs to the deposit now described. 



Towards the west of Edinburgh, boulder-clay covers the country. Near 

 Redhall, it may be seen lying upon the sandstone rock quarried there, to the 

 depth of 20 feet, and containing large blocks of greenstone and basalt. One of 

 these blocks is not less than 40 cubic feet in size. 



With regard to the depth or thickness of this lowest deposit, my inquiries 

 have not been so successful as to enable me to afford much information. Along 

 the sea-shore it is about 45 feet at Leith, and it is said more than 60 feet at 

 Portobello. In the quarry at Cowpits it is only 8 feet thick. In the borings 

 lately made by the Duke of Buccleuch to the SE. of Dalkeith, it varies from 9 

 to 15 feet. Between Carlops and West Linton it is from 4 to 20 feet thick. 



There are some places, however, in Mid-Lothian where the depth is much 

 greater, arising from a circumstance very remarkable. At Niddry, where the 

 " great seam" of coal was worked, the depth of all the superficial deposits was 

 found to be between 60 and 70 feet, of which about 30 feet was clay full of 

 boulders. Here, it was ascertained, there had been a scooping out of the rocks, 

 to a certain depth, and that the excavation was filled with the clay. The exca- 

 vation cuts across the crop of the strata, and near Niddry it is about 100 yards 

 wide. It runs in a NE. direction, and has been proved at several places in that 

 direction. It was proved at the Wisp, where the " great seam" was worked. It 

 was proved about 1000 yards to the east of this, by certain borings. It was also 

 proved at New Craighall, which is about two miles east from the Wisp. The 

 depth of the boulder-clay at this last point was 48 feet, overlaid by other 48 feet 

 of different deposits, to be afterwards described. The width of the excavation at 

 New Craighall is about 200 yards, being nearly double what it is at Niddry. The 

 sides or waUs of this excavation do not appear to be vertical. At the bottom of 

 this channel, the boulders are said to be entirely of blue whin, and so close as to 

 be almost touching. The above particulars I learnt from the late John Grieve 

 of Musselburgh, who was coal-manager for Sir John Hope, and who, in describing 

 this excavation to me, stated that it was in every particular like the course of 

 the river Esk at Hawthornden ; and that he had no doubt but that this was an 

 ancient river course, which had been choked up with the boulder-clay. I do not 

 mention this now for the purpose of theorizing, and far less for the purpose of 

 offering Mr Geieve's theory as the true one. I notice it only for the purpose of 

 conveying an idea of the nature and extent of the excavation in question. I 

 thought at first that it might have been owing to a fracture across the strata, of 



VOL. XIV. PART I. R r 



