GEOLOGY OF NORTH GTPPSLANI), VTCTORTA.
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foundation " which is seen at the Black Mountain or Fanwick is no longer visible, having sunk below the level of the rivers.
In constructing this diagram sec- tion, I admit that much of tbe sub- terranean representation must ne- cessarily be hypothetical, and its possible truth must depend, in a great measure, upon the accuracy of my observations and also upon the soundness of the inductive rea- soning based upon them.
In the observations made as to the surface appearances, I can feel the confidence which has been created by repeated examinations during the last five or six years ; of those features I have inferred to exist, such as the subterranean ex- tension of the Silurian strata of the Limestone River and the position of the central mass of quartz-por- phyries, I may say the following words : —
At the north-west end of the sec- tion the limestones and slates sud- denly end at the foot of the por- phyry hills forming the east side of the Limestone Eiver ; they present no more than the normal degree of disturbance or alteration, nor any such appearances as would lead me to suspect that the igneous rocks had come up through them. On the contrary, where last seen, they appear merely to pass under the great mountain of porphyritic rock which there forms part of the Great Dividing Range. These rocks themselves are found on ex- amination to be principally quartzi- ferous felstoncs, which I regard as merely altered ash ; for almost everywhere the weathered surfaces show more or less of the fragmen- tary nature of the composition. I am informed by persons who have prospected for gold in the streams falling into the Limestone River from the Great Dividing Range at
