38 



lands or out to the bed o£ tlie sea. In tMs way a periodical 

 ctange in tlie currents and eddies of the streams would be set 

 up ; one part of tbe cbannel would alternately become a natural 

 obstruction to tbe passage of solid material, until the deposits 

 assume the proportions we now witness. 



Fundamental Eocks. 



Form of the Ground. — On reference to a map of the 

 Hundred of Saddleworth, it will be seen that the general trend 

 of the River Gilbert through that Hundred is conformable 

 with the direction of the Manoora range of hills on the west 

 and the Steelton range on the east. In the neighbourhood of 

 Manoora, the altitude of these hills is estimated at about 300 

 feet above the level of the township). 



Both ranges owe their present outlines, in a most marked 

 degree, to the nature and character of the fundamental rocks. 

 The crest of the Steelton range, being traversed for many miles 

 by an extensive, hard, and tough band of quartzite, leads me to 

 infer that whilst the less durable clay-slate was removed by 

 denusive agency, the more resistant quartzite better withstood 

 the continuous ordeal of tear and wear. 



The Manoora range contains two quartzite bands, which are 

 composed of a fine material and apparently vary in their 

 degree of induration; in consequence of which has arisen, 

 under denusive action, that distinctive feature of the range — 

 that of a confused chain of hummocky knolls. The quartzite bands 

 of the Steelton range, on the other hand, has yielded more 

 regularly to destructive agencies, and in this way has deter- 

 mined relatively greater uniformity of outline, which belongs 

 to this range. 



Nature of Strata, — The rocks occupying the western side of 

 the district, at least in the neighbourhood where the sectional 

 line intersects, have been subjected to anticlinal folding. A 

 very fine section of the western limb of this fold, as rej)resented 

 in the quartzite baud, is exposed in Kelsh's Quarry (section 

 310). Here the beds repose at the inclination of S0° to the 

 west, the strike is mag. north. Another quarry has been 

 opened on section 311, and developed to a considerable extent 

 on the eastern member of the fold ; here the inclination of the 

 beds is 85° east, strike also mag. north; estimated thickness of 

 the band in each quarry 200 feet. The prevailing character of 

 stone in both quarries is a fine-grained, slightly micaceous, 

 quartzite; that from the western fold has a bluish-white 

 tinge, whereas that from the eastern is chiefly of a light brown 

 and approaching to pink. Heretofore the quarry situated 

 in the western limb of the anticlinal fold has been most ex- 

 tensively developed, the excavation reaching from fifty to sixty 



