844 Albert V. James: 



beds which contain no basalt. These deposits have been dropped 

 by the stream as it deepened its bed, but yet the fact should be 

 noted that the great mass of this conglomerate occurs about 100 feet 

 above the present stream level, i.e., when the stream had sunk its 

 bed a little more than 100 feet below the surface. This shows that 

 at that depth the stream cut into an old Kainozoic pebble deposit 

 to the north, and distributed the pebbles on the convex bank of its 

 meanders. The pebbles lower than 100 feet have probably been, 

 derived partly from the old pebble beds, and partly from the recent 

 deposits higher up the spurs. 



River alluvium, as already described under Physiography, is- 

 poorly represented in this area. It is found chiefly on the down- 

 valley side of the spurs, and it usually passes into and overlies a. 

 heavy river conglomerate, the best deposit is found on Jackson's- 

 Creek, near its junction with Deep Creek. 



Newer Basalt. 



Newer basalt covers more than nine-tenths of the area mapped. 

 It appears to consist of about seven flows that havei come from Red 

 Hill, Sunbury Hill and Bald Hill. This is shoAvn by the contour 

 lines on the military map, by the dominating position of these vol- 

 canoes, and by the shape and direction of the vesicles in the basalt. 

 The points of origin of the earlier flows have not been determined. 

 In many places the basalt has a depth of over 300 ft., but it cannot 

 be said from this that each flow is 43 ft. in thickness, for the earlier 

 flows are by far the deepest, since they levelled the old denuded 

 surface. In the neighbourhood of Column Gully excellent col- 

 umnar structure has been produced in the earlier flows. A de- 

 scription of these columns (14) and the factors producing them (18) 

 may be found in other publications. 



Ujjper and Lower Series. — The various flows of newer basalt in 

 this area are divided into L^pper and Lower Series by sandstone 

 bands, river conglomerates, or thick surface soil. The places where- 

 a good junction of the Upper and Lower Series can be seen i» 

 marked F on the map. Tliat a considerable time interval elapsed 

 between the two series is shown by tlie denuded surface of the 

 Lower, by its older appearance and more decomposed state, and 

 by the thickness of surface soil on the Lower Series. Generally the 

 thick scree on the valley sides masks the division line of the two- 

 series, but excellent junctions are common, especially in the N.W.. 

 of the area. 



