MR MILNE ON THE MID-LOTHIAN AND EAST-LOTHIAN COAL-FIELDS. 271 



opposite to each other, but on one side have sunk down, or on the other side 

 risen up, — in some cases to tlie extent of several hundred feet. 



I have been at considerable pains to obtain information regarding the slips 

 which occur in the district. The subject is one of extreme difficulty, arising from 

 the circumstance, that these slips can very seldom be discovered except in carrying 

 on mining operations. They are seen, therefore, only by the working collier ; no 

 geologist need attempt to find them and trace them himself. He must depend 

 entirely for his knowledge of the subject, on information to be elicited from others ; 

 and those others unfortunately belong in general to a class of persons, who are 

 neither very intelligent observers, nor very able to explain with accuracy what 

 they have observed. 



Notwithstanding these obstacles and disadvantages, I have been able to col- 

 lect information regarding about 120 different slips. I have drawn green co- 

 lom*ed lines on the accompanying map, indicating the places through which the 

 most important of these slips run, and the direction of their course. The particular 

 spot where they have been proved is in general marked by a x drawn upon these 

 lines. It is unnecessary for me here to enter into any particular account of the 

 effects of each particular slip. There are about 110 of them marked on the map, 

 and numbered with reference to a table annexed to this memoir, which shews 

 exactly the circumstances and effects of each.* I may merely mention, that the 

 gi-eatest slip known in the district is what is called the Sheriff'hall slip. It runs 

 N.W. by W., and has produced a dislocation of the strata to the extent of 400 or 

 500 feet ; that is to say, the coals which are worked on the south side of the slip 

 near the surface, are on the north side of the slip 400 or 500 feet down below the 

 surface. 



I shall now notice what appears to me the most important circumstances 

 characterizing the slips of this district. 



(1.) They are all of unfathomable depth. There is no instance of any slip 

 which comes to the surface, having been found to end or disappear at any depth 

 to which coal operations have reached. 



There is one example known of a slip which does not come to the surface. 

 It is in the Sheriff'hall colliery. There are there three seams of coal, viz. the 

 Beefle coal, the Diamond coal, and the Jewel coal, the last mentioned being the 

 lowest. This slip cuts througli the two last mentioned seams, but it does not 

 reach so far up as the Beejie coal. This slip runs due N. and S. It is not marked 

 on the map or on the table of slips. 



(2.) The next point deserving of notice on this subject, is the direction of the 

 slips as they appear on the surface. This information is afforded by the table 

 I have compiled ; and it may be obtained also by inspecting the map. 



On an examination of the table, it will be seen that, out of 109 slips the 



* For this table, see Appendix D. 



