338 GEOLOGICAL APPEARANCES ' 



succeeded by a body of strata, stretching obliquely across the 

 stream, which is cutting its passage through them. They ex- 

 tend about twenty yards along the northern bank, and twenty- 

 five along the southern, and consist for the most part of gneiss, 

 hornblende-slate, and granular limestone. Some of the horn- 

 blende-slate on the noi'th side of the river, is a pure schistose 

 hornblende, similai' to that which forms the pieces imbedded 

 in the rock at 8. The average stretch of these strata is about 

 N. US'" E., and their dip to the south-west at an angle so large 

 as 64°; but there are some irregularities from shifts aud bend- 

 ings. In the strata of limestone there are many small undu- 

 lations, which are clearly marked on the horizontal surface, by 

 parallel curved ridges of interstratified hornblende and felspar : 

 these harder substances have been left projecting, while the 

 softer limestone has been worn away by the water. Fig. iir, 

 in PlateXIX, shews the curvedline of oneof these undulations on 

 the north side of the river. I think that the breadth from x to 

 y may be about a foot. 



90. The strata along the northern bank are not much inter- 

 sected by veins of the sienite ; but those along the southern are 

 so in the most striking manner, especially in the neighbour- 

 hood of the main rock of sienite. A blast in the rock on the 

 southern bank procured us specimens of these veins, where 

 they run through some strata of a dark colour, consisting of 

 hornblende, intimately mixed with talc and carbonate of lime, 

 and shewed us that a section of this part of the rock, in any di- 

 rection, would exhibit a complete net-work of them. The 

 spot, where the blast was made, is near 9 in the plan. From 

 hence I traced the veins in an oblique direction towards the 

 bridge, irregularly branching, and again uniting, among the se- 

 parated masses of the strata, to their junction with the main 



body 



