174 Observations on some Metamorphic Rocks 



all, though still preserving former lines of stratification, so that 

 this difference must be entirely attributed to mere local causes. 

 Now as to the probability of parallel cracks. If these were 

 made at all, they would probably give rise to dykes of trap. 

 But if owing to some unknown cause, the cracks only extended 

 through some strata, and not through others (more moderately 

 tilted, for instance), the trap would stop some distance from the 

 sur face, and crystallise the stone above. I know this appears 

 far-fetched, but we must' remember that far less probable theo- 

 ries have been verified by investigation. 



There is, however, another cause to which the bands may be 

 attributed. They may have arisen from under-ground flows 

 of lava, prior to the raising of the hills. This view has only 

 two circumstances to support it. There is an extinct volcano 

 about thirty-seven miles to • the N.N.W., above the river 

 Brouo-hton, and we know from experience, that lava occasionally 

 flows underground. The volcano I allude to, which I never had 

 an opportunity of examining closely, appears to have greatly 

 disturbed the features of the country around ; and may pro- 

 bably be not yet quite extinct, as shocks of earthquakes are 

 frequently felt at Mr. Fisher's home station at Bundalier (some 

 of which have shaken the walls of the house) ; and what is of 

 more importance just now, this volcano has given rise to im- 

 mense quantities of lava. It is not difficult to suppose lava to 

 have flowed under ground for such a distance, and if it did it 

 would have given rise to such appearances as the bands. I may 

 mention a case by way of illustration. In a paper I have pub- 

 lished about the geology of Mount G-ambier, I have shown that 

 the lava has there flowed under ground. At Mount Schank it 

 has come to the surface, and though it appears in the form of 

 trap rock, it runs in a band similar to the one we are here 

 speaking of. But the resemblance is more striking even than 

 this. At Mount Schank, where a second flow of lava has oc- 

 curred the uppermost flow has been forced into upright 

 boulders, and appears in form exactly like one of the bands 

 which occur in a valley. Now, as from a second flow of under 

 trap, we should expect an appearance like the bands, from the 

 way the cool trap would be tilted up : the trap in this case 

 occupying exactly the place of the metamorphic rock. The 

 similarity is, to say the least, very remarkable. 



But supposing neither theory to be the true one, we are 

 not entirely at a loss to suggest a cause. There is evidence of 

 upheaval nearly in the same direction at distinct periods, show- 

 ing a uniform disturbance in the same place at different times. 



