124 G. H. KimJian—A Faulted Slate. 



is a right-hand heave that jumps the lode southward, adding to 

 the lode an equal length to that 

 "which in the perpendicular was 

 cut otf by the left-hand heave. 

 This lengthening of the lode 

 could not have taken place by 

 the means of an upward or down- 

 ward throw, unless the strata 

 alongside the right-hand heave 

 was shoved upward ; while it -n- tt _ « jr ,. 



could quite easily be due to a 

 northern heave of the strata between tbe two parallel fault lines. 



If we now turn to that beautiful portrait for which we have to 

 thank Mr. Teall, we find reverse breaks, but on a very small scale. 

 In the portion below the main fault, in the riban between the 

 two dark portions, we have, beginning at the bottom, B.H. (a right- 

 hand beave) ; L.H. (a left-hand heave); L.H. ; B.H. ; B.H.; and 

 L.H. ; the left-hand heaves being reverse faults ; but the ovei'laps 

 are not well exemplified, on account of the faults being perpen- 

 dicular to the layer. If, however, we go above the main fault, we 

 find a faulted riban in the light portion ; this gives, going up from the 

 main fault ; B.H. (a right-hand heave) ; L.H. (a left-hand heave) ; 

 B.H; L.H.; L.H; L.H; B.H; B.H; L.H; L.H; and B.H., 

 the three principal left-hand heaves being oblique to the riban, and 

 therefore causing overlaps. It is also v^^orthy of observation that most 

 of the faults in this riban do not extend out of the light portion into 

 the dark ; also, that the margin of the latter does not coincide with 

 the plane of the riban ; this can also be seen, but not so conspicuously, 

 in the portion to the south of the main fault. 



These faulted slates and the riban are very interesting, and 

 have long attracted my attention. The riban in general is sup- 

 posed to be the stratification ; but I have found in various places 

 in the Carboniferous slate of the co. Cork, in some beds in 

 the Killaloe slate quarry, and in the slate veins of Slieverne, co. 

 Wexford, the riban crossing the vein. This is very conspicuous 

 in the variegated slates of the latter locality, as the veins extend 

 eastward and westward, while the riban crosses them in wavy lines, 

 sometimes dipping eastward, other times westward. I do not, how- 

 ever, mean to say that the riban never coincides with the stratifica- 

 tion, because, as far as my experience goes, it in general does. 



Somewhat similarly these minute faults appear to be confined to 

 certain beds, while they do not extend into the strata above or below. 

 I have observed this in beds of slate in the cos. Cork, Waterford, 

 Wexford, Wicklow, and Galway ; while the same thing occurs but 

 on a much larger scale in the Lough Muck beds (Silurians), near 

 the north boundary of the co. Galway, a certain series of ribaned 

 shales being excessively faulted, the faults not extending into the 

 beds above and below them. The fact that the beds thus faulted 

 are of unequal thicknesses, as can be seen in the lower portion of 

 Mr. Teall's Plate, has lead me to believe that these dislocations 



