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



Tlie operation of these two forces would, when combined, produce an almost 

 inconceivable number of dislocations. This will appear the more evident if we 

 observe what must be the consequences of single dislocations, from whatever 

 cause produced. Suppose that a fissure takes place, intei-secting all the strata for 

 a mile in horizontal extent, and to a depth of more than 100 j^ards. The strata 

 on one side or the other of this slip would be pushed up or would sink down, ac- 

 cording to the natm-e of the force which produced it. But it is difficult to con- 

 ceive, that under such ch'cumstances, this would be the only dislocation produced. 

 Others would take place in the district, some of Avhich would probably intersect 

 and unite. The slips mai-ked on the map 112 and 113, are an example of this. 

 It will be seen fi-om an inspection of the table, that the strata on the outside of 

 these slips have sunk doAvn, leaving the triangular parts comprehended be- 

 tween them standing up. Suppose that the parts comprehended between that 

 triangle and the slips 01 and 02, had sunk down simultaneously. Unless the 

 slips 01 and 02 are prolonged indefinitely,^— there must have been a cross fracture 

 produced somewhere, — beyond which the sinking did not extend. Then there 

 must in like manner have been a fracture intersecting 112 and 113 ; so that, in 

 general, every dislocation would be accompanied by, because it would occasion, 

 several others. 



There ai-e very many examples in the district, of slips changing their direction. 

 Two of these, near each other, are marked on the Map, and relative Table, on both 

 of which they are numbered 73. Another instance may be mentioned, which was 

 lately observed on opening a pit on the Edmonstone property, called on the plans 

 Pit 23. After sinking the pit P, a dilffc Pd was made towards the NE. When at 

 a distance of 10 j'ards, a slip A A' was discovered running N. 35° W., and throwing 

 the strata dowTi on the NE. side from 15 to 20 feet. Another drift Pc was made 

 from the pit bottom towards the SW., when at a distance of 

 22 yards, another slip B B' B" was discovered running N. 50° W. 

 This slip, at the distance of about 34 yai'ds from the pit, took 

 a turn B', and ran N. 45° E. for a short way, after which it ran 

 on in nearly the same direction as before. At B" (about 154 

 yards from the pit) the strata were found to be downcast on 

 the NE. side 12 feet. At B the amount of doAvncast is 15 feet. 

 The slip B B' B" imites with A A' a little to the NW. This last- 

 mentioned slip is known to run a considerable way farther in 

 that direction. The strata which these two slips intersect dip 

 towards the SE. 



It is probable, that the slip B B' B" was formed subsequently to the slip A A'. 

 As the amount of dislocation produced by the former, is towards the SE., or trough 

 of the basin, that slip may have been occasioned by a subsidence of the parts 

 situated towards the NE. side of B B' B". The deviation of this last slip at 



