SY w. N. bp:nson. 257 



the Blue Knob laccolite, and appears from under the basalts of 

 the Nandewar Range. In the cliffs of the Manilla gorge, con- 

 tortion of the mudstones is clearly visible, not in contact with 

 the sill, but about fifty feet below it. The sill continues south 

 of the I'iver around Tareela Mountain, and has been noted near 

 the head of Hawkin's Creek. As it has not been actually 

 mapped, however, it is impossible to say how far it has been 

 affected by the fault which is believed to occur along Hawkin's 

 Creek. 



North of the Manilla, the Middle Western Zone is crossed by 

 the Nandewar Range, composed of basalt covering Tertiary 

 drifts. This will be described later (p. 2 7 6). North of this is 

 the Cobbadah district. West of the fault bounding the Carbon- 

 iferous Series described above (p. 241), are gently dipping, Lepi- 

 dodeiidron-hesLring mudstones, as at Barraba; and these may be 

 traced along the main road to the head of Hall's Creek, nine 

 miles to the north. Passing down Cobbadah Creek (Section 2, 

 Plate XX.), the easterly dip of the Lepidodendrou-nmdstoneH 

 gradually diminishes, and, after a small fault north of Dunee 

 homestead, it changes rapidly to the west, and a heavy fault 

 occurs just below the junction of the northern Oakey Creek. 

 This is a most complex fault (see Text-fig. 7), but its total char- 

 acter is that of a downthrow to the east, bringing the Baldwin 

 agglomerate near to the surface on the west. The upper sur- 

 face of this agglomerate is undulating, and the small plexus of 

 faults which follows Inings it to the land-surface, or leaves it 

 covered with Barraba rocks in a manner clearly shown by map 

 and section. The strong difference in relief of the two forma- 

 tions makes the tracing of fault-lines very easy. 



AVest of this, the stream crosses another great fault with an 

 easterly downthrow of perhaps 800 feet, bringing the agglomerate 

 up into a great ridge, through which Cobbadah Creek cuts a 

 gorge, in which it is joined by Anderson's Creek, before it opens 

 out on to the Horton Valley. 



This gorge affords the best section available for the study of 

 the Baldwin agglomerates. They have a gentle variable inclina- 



