STRATA of the GRAMPIANS. 17 



trition), confift, in general, of oblong fquare fhapes. This ob- 

 fervation, when I firft made it, led me to imagine, that thofe 

 rocks here were perhaps ftratified. I have, however, as yet, not 

 been able to trace real flratiflcation of thofe rocks in this diftrict 

 of the Grampians. 



Upon fome of the fummits of thofe hills which here form the 

 balls of the central range, I firft difcovered the granite in folid 

 rock. In thofe fituations, the granite is only feen in patches, 

 where the fuperincumbent rocks have worn off it. Thefe fu- 

 perincumbent rocks, which I here found in contact with the 

 granite, are of two different compofitions, and occur on the fum- 

 mits of different hills. The one of thofe rocks, and the moft 

 prevalent one, is the micaceous fhiftus ; the other is the granitelle,. 

 or a mixture of quartz and fhorl. In fome parts of this laft- 

 mentioned rock, I perceived a fmall admixture of hornblende : 

 where this appears in the compofition, it perhaps ought to receive 

 the appellation of granitine. In thofe elevated fituations, I 

 found both of thofe rocks, (efpecially the micaceous fhiftus), in 

 a ftate of decompofition, and faft leaving the granite expofed to 

 the eye. 



From thofe appearances, it is to be inferred, that the interior 

 of thofe hills is compofed of granite, which is but thinly coated 

 by the fuperincumbent rocks. 



Upon leaving thefe hills, which, I have already faid, form 

 the bafis of the central chain of the Grampians, I regretted 

 very much, that all my endeavours proved abortive to trace out 

 the whole extent, in line, of any one of thofe dikes of porphyry 

 which interfedl their fides. I conflantly loft them under peat or 

 other foils, before I could trace them to their contact with the 

 granite. It was my anxious wifh to fee how thofe two rocks of 

 porphyry and granite connected with each other at their junc- 

 tion. 



Yol.VL— P.L C In 



