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



to 12 feet thick. At Niddry, and all over the district to the east, it also rests on 

 the boulder-clay. At New Craighall it is about 40 feet thick. At the Duke of 

 BuccLEucii's new engine-pit it is 23 feet thick. 



At the places just mentioned, this stoney clay is lying upon the boulder-clay. 

 I may next mention some places where it is Ijdng immediately on the rocks. In 

 that part of the Leith and Dalkeith Railway which is to the south of the turn- 

 pike road leading from Brunston to Duddingstone, the strata of shale are seen 

 nearly vertical dipping SE., and overtopped by a bed of stoney clay 15 feet thick 

 The boulder-clay appears to have been denudated at this point, for a little to the 

 north it takes on again, under the stoney clay. 



4. Beds of fine clay, form the next member in the series of deposits in this 

 district. 



The clay is generally fine, free from stones or gravel, and laminated horizon- 

 tally. It is of various colours, being sometimes dark yellow, sometimes light brown, 

 sometimes dark brown, sometimes having a shade of blue in it. From Harden 

 Green to the Duke of Buccleuch's new brick-work, two mUes east of Dalkeith, 

 this clay appears to form one continuous bed. It is throughout of a brownish- 

 yellow colour, and is overlaid by sand. Beneath the clay at these places is what 

 1 have tei'med the gravel or stoney clay. The same bank or bed continues to the 

 SW., and is worked at Redheugh on the Arniston property. How far it stretches 

 towards the NE. is not known. Near the Duke's Kennel it is more than 15 feet 

 thick. At the Cowpits, where the coal- engine was, the bed was (as Mr Grieve 

 infoi-med me) between 20 and 30 feet thick. It does not appear to exist in the 

 old quarry situated to the north. 



It is at PortobeUo that this particular clay is most extensively worked. It 

 is now worked in two or three several places there, at the north end of the town. 

 It was formerly worked in another place more to the south of any of the present 

 brick-fields. It was also worked (about fifteen years ago) a mile to the west of 

 PortobeUo, on the south side of the Edinburgh road. 



At PortobeUo, the clay which is worked in the brickfields, consists of two beds, 

 the lowermost of which is more clammy or (to use the expression of the work- 

 men) strowjer and fatter than the other. Both these beds or layers dip at the 

 Edinburgh road towards the SW. with an angle of about 10°. This basin of clay 

 extends eastwards nearly as far as Joppa, where it rises up and thins off. To- 

 ward the SW. it stretches to Duddingston Mill (where it was once worked), and 

 there is reason to believe that it extends through the grounds of Duddingston 

 House, and even as far as the Inch. I have reason to believe, that a similar bed 

 of clay exists in the Cowgate of Edinburgh, for I have heard, that in digging out 

 the foundations of the South Bridge of Edinburgh, a thick bed of cockles was 

 discovered. 



