156 Craigmillar and its Environs. 



other hand, upwards of 2500 feet of strata occur 

 between the two hmestones on the west side. The 

 oil -shales, so extensively worked in Mid -Lothian 

 and Linlithgowshire, belong principally to this division 

 of the Calciferous Sandstone group, namely, between 

 the two limestones of Burdiehouse and Gilmerton. 

 The Carboniferous Limestone series — the next divi- 

 sion following the Calciferous Sandstone — begins in 

 the district with the Gilmerton Limestone — the 

 bottom limestone of the group. Above this other 

 two limestones occur ; following these, a series of 

 sandstones, with several workable seams of coal ; 

 then an ironstone ; and above these again, other 

 bands of limestone, forming the top of the group. 

 The coals and ironstones are extensively worked in 

 the neighbourhood of Loanhead, Gilmerton, and 

 Niddrie. Owing to the Pentland fault, the strata 

 adjoining it are highly inclined, and are known 

 locally as the " edge coals " ; above these comes 

 the third group of strata, known as the Millstone 

 Grit ; and finally, on the top of the Millstone Grit, 

 the last division of the Carboniferous System — the 

 Flat or true Coal-measures of the Dalkeith coal-field. 



