MR MILNE ON THE MID-LOTHIAN AND EAST-LOTHIAN COAL-FIELDS. 309 



(6.) Coarse gravel or stoney clay. 

 (7.) Lowest boulder clay. 

 (8.) Beds of sand and gravel. 

 I shall begin with the lowest of the deposits now enumerated. 



1. Beds of Sand and Gravel. — This deposit has been observed in several parts 

 of the district, covering the edges of the stratified rocks. It prevails extensively 

 in that part of the district situated between Dalkeith and Cowpits. Some years 

 ago, coal was worked at the latter place ; and in sinking various pits through the 

 superficial clay and gravel, a bed of sand \ymg immediately on the rocks, was in- 

 variably passed through, which, being full of water, occasioned great practical dif- 

 ficulties, and even risks, to the work-people. A few months ago, a similar bed of 

 sand was met with on the Duke of Buccleuch's estate, near Dalkeith, in sinking 

 an engine-pit to work the coal. The pit had been formed through the boulder- 

 clay, on reaching the bottom of which a bed of sand was encountered, which 

 suddenly gave way, and laid the building in ruins. It was found necessary to 

 form a new pit at a different place,-^above the level to which this particular de- 

 posit reaches, — which appears to be about 200 feet above the sea. At the place 

 where the first pit was put down, the sand was 9 feet thick, and between it and 

 the rocks there was a mixture of sand and fine gravel 7 feet thick. 



At Joppa likewise, (at the east end of the village, near the shore), the clay 

 is separated from the subjacent coal-measures, by a bed of sand 5 or 6 feet thick. 

 This sand-bed was found in the borings made for a particular coal-seam there, 

 called the Splint Coal. The sand-bed covered this seam ; — fragments of the coal 

 were found in the sand, to the distance of 10 yards fi-om the crop or outburst of 

 the seam. It is not unimportant to observe, that, in the sand-bed, these frag- 

 ments were all situated to the west of the coal-seam. Some fragments were also 

 found at the bottom of the superjacent boulder-clay ; — these were situated mostly 

 to the east of the coal-seam. 



At Leith, and in the manufactory lately occupied by Mr Burstall, a well 

 was sunk through the boulder-clay 45 feet. A bed of sand and fine gravel was 

 then reached, from which water immediately gushed up, — shewing that the bed 

 was probably of considerable extent. 



2. The Lowest Boulder Clay. — This deposit consists of a very hard coarse clay, 

 of a colour generally blue or black, and having sometimes in it a shade of broAvn. 

 Its texture is coarse and gritty. No laminae are visible in it, such as may be seen 

 in tranquil deposits of clay, and in most deposits of sand. It is difficult to work 

 or excavate it, being quite impervious to the spade, and requiring the heavy pick 

 to loosen it. It comes off in fragments of irregular shape, which on no side pre- 

 sent any smooth, even, or regular surface. 



