102 ON THE CONVOLUTIONS OF STRATA, 



Several small veins were found to cross from the dike to 

 the main mass, having an identity of substance throughout. 

 That which is represented in the model, incloses a triangle of 

 killas, whose sides are seven feet by five ; the strata being 

 here moved by a small shift. Many other smaller veins oc- 

 curred of the same kind, and in the same position, which have 

 been omitted as too minute. The dike, near its exit, also ex- 

 hibits a fine example of another most important and instruc- 

 tive circumstance in geology. The granite actually contains 

 a mass of the stratified body included in its substance, and 

 surrounded on all sides with granite. 



In the immediate neighbourhood of the granite, to the dis- 

 tance of a foot or two, and not more, the stratified matter has 

 in many instances assumed a highly micaceous character, so 

 as to deserve the name of Mica-slate, and perhaps of Gneiss. 



Every thing seems to indicate that those dikes, which ap- 

 pear on this hill in such abundance, and which have been 

 shewn in this case to be continuations of the same mass, have 

 come from below ; and this opinion seems to be strengthened 

 by the fact, that on the north-west side of the same Windy 

 Shoulder, the granite at the junction seems to dip under the 

 killas. From the shape of the ground, sinking rapidly below 

 the line of junction, I expected easily to reach the granite, by 

 blowing up with gunpowder the killas at some point beneath 

 this line. The first blast did not succeed ; but a second, near 

 the junction, was very effectual. It rent the mass at right 

 angles with the junction, by which the granite is seen actually 

 to dip under the killas, as at first supposed, with an irregular 

 line. 



The surface being dressed at the emergence of one of the 

 small veins from the great mass, the following curious fact 

 presented itself. To the distance of about three inches with- 

 in 



