4 



length bounded by slates dipping eastward. Ascending tbese- 

 slates, the sandstone cap is found to get liner and finer grained 

 until, as before stated, it becomes a freestone quarried for 

 building purposes. AVhere not resting directly on primary 

 rocks this sandstone rests on blue clay similar in appearance to- 

 that found under the red clay of the plains. Such is the case- 

 at Tothill's Creek, Butcher's Gap, AV^oolshed Flat, Salter's- 

 Springs, and Humphrey's Springs. 



The frequent occurrence of similar patches of conglomerate 

 in the beds of creeks which are still the main drains of the tract 

 of country m which they are situated would at first sight ap- 

 pear to indicate that the sandstone just spoken of had its- 

 origin in running streams. The bedding of the sandstones, 

 however, their dip and variation in texture, while indicative of 

 formation by currents is not consistent with lacustrine or river 

 depositions when considered in the light of their altitudes and 

 distributions over extensive areas. 



PETMAET EOCKS. 



The series of slates, quartzites, and crystalline limestones 

 forming the main mass of the ranges have been tentatively 

 classed under the somewhat ambiguous term of " pre-Silurian," 

 which term, however, commends itself as being indicative of 

 the extreme age to which these rocks undoubtedly belong. 

 Along the line of section they are clearly divisible into twO' 

 groups — an upper and lower — both upheaved and greatly 

 faulted, and unconformable to each other. 



Upper Group. — The upper group is much the thicker of the 

 two, and consists of slates, soft aluminous rock, quartzites, 

 flags, and sandstones. It is seen to best advantage in the- 

 Giibert A'^alley along the line of section which passes through. 

 Eiverton. In descending order the rocks here met with are 



Greenish grey sandy slates and soft aluminous rock. 



Pink and brown earthy slates. 



Blue slates containing black iron pyrites. 



Olive green slate. 



Brown quartzite. 



Olive green sandy slates. 



AYhite slatey sandstones, soft and sometimes earthy. 



Blue flags. 



Bluish grey sandstones graduating into micaceous flags. 

 All the above beds are seen in ascending order from about 

 one inile west of Eiverton to the foot of the Marrabel range, 

 about four miles further east. The prevailing strike is N. 10 

 W. and dip eastward at a mean angle of 23 deg. from the 

 horizon. Xumerous quarries abound in the three lowest beds 



