2 On the Caves Perforating Marble 
of Mount Pilot, 6020 feet ; to the cast tower the serrated 
rocky ridges of the Cobboras mountains, 6025 feet ; while 
intervening and winding amid bold, wooded ranges lies the 
gorge formed by the Limestone Creek valley. Along the 
course of the stream are a series of richly grassed open flats, 
backed m many places by low bluffy spurs, giving in their 
undulating contour and other appearances unmistakable 
evidences of calcareous deposits in situ. 
Geological Structure. 
The eastern watershed (with the exception of the locality 
hereinafter mentioned as Stony Creek) is composed of 
masses of porphyries, fragmental and compact, the former 
from grains as fine as sand to blocks weighing many tons ; 
while the western watershed is made up principally of 
slates, and interbedded bands of whitish marble and dense 
blue limestone. The slates merging on the western water- 
shed line into a class of schistose rocks, bearing a stroncf 
resernblance to the metamorphic schists of the Omeo 
District.* Although the Limestone Creek may generally be 
said to have eroded its course along the contact of the 
sedimentary rocks with the porphyries, yet the latter, in 
the lower part of the stream, have been cut through, leaving 
precipitous banks on either side. 
In Older that the stratigraphical relation of the porphy- 
ries to the sedimentary rocks may be better understood, 
the following sectional notes and diagrams are given. The 
section was determined from personal observation, and 
crosses the Limestone Creek valley at right angles to the 
course of the stream. 
Starting from the level of Marengo Creek (an eastern 
affluent of the Mitta Mitta), and proceeding easterly, we 
have, first, a mass of granitiform rock exposed on the bed 
of Marengo Creek ; ascending Mount Pendergast coarse 
metamorphic schists, gneissic in character, are seen, showincf 
apparently a vertical dip. As the crest of the range is 
reached these rocks become more micaceous, full of thin 
quartz seams, and corrugated along the line of strike, which 
is here seen to be N. 20'W. Descending towards the Lime- 
stone Creek some upland alluvial flats are passed over, with 
* " The Diorites and Granites of Swift’s Creek, and Their Contact Zones.” 
By A. W. Howitt, F.G.S. Royal Society of Victoria, pp. 9 to 15. 
