Mineralogy of Sky. 163 



offered only conjectures on the similarity of the series, I do not find 

 those conjectures verified ; the position of the beds becoming first 

 vertical and then reversed and irregular; ultimately settling in a 

 dip towards the east, the reverse of that which predominates on the 

 western or upper side of the series. But whatever irregularities 

 are found in the dip, there are none in the direction, which with a 

 slight local disturbance near Ord is invariably rectilinear, and on 

 the north-east line or nearly so. 



On the north-eastern end of this series, where it forms the 

 mountains of the Kyle, the rocks can be traced perfectly from the 

 gneiss at Isle Oransa to the commencement of the limestone near 

 Broadford, this space comprising the collective thickness of the 

 strata ; but through this tract the quartz rock or indurated sandstone 

 is predominant. If these strata are prolonged toward the south- 

 west their characters change, or they are discontinuous in com- 

 position according to the line of their direction, since the schist and 

 quartz rock are most abundant toward the north-eastern end, while 

 red sandstone prevails at the opposite one. 



The space which they have been represented to occupy on the 

 original map must also be extended, and to a certain degree this 

 may be done by prolonging the line of direction from that point 

 near Isle Oransa where the junction of the gneiss is found. 



I have already related the error committed by allowing too much 

 space to the micaceous schist, which occurs only as one of the 

 members of a series principally formed of gneiss and chlorite schist. 

 Another of the sources of that error will now appear when I 

 describe the last enumerated member of the red sandstone series ; 

 and it will no less excite surprise than operate as a caution in the 

 present state of geological science, against judging of rocks by 

 analogies, or by any other evidence than that of actual and careful 

 examination. 



