STRATA of th 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 ftratification of thofe rocks in this diftri@ 
of the Grampians. 
Upon fome of the fummits of thofe hills which here form the 
bafis 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 contaét 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 {mall 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 {tate 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 interfeé their fides. I conftantly loft them wider peat or 
other foils, before I could trace them to their contac with the 
granite. It was my anxious wih to fee how thofe two rocks of 
porphyry and granite connected with each other at their junc- 
tion. 
Vou. VL—P.1L C In 
