248 C. A. SUSSMILCH. 



Several possible explanations for these differences suggest 

 themselves. The Kattung Series were deposited under 

 terrestrial conditions, and the high land which supplied 

 the sediments may have occurred immediately to the south 

 and south-west of the Hunter River area; if this were 

 so one would expect the thickness of the sedimentation, 

 and particularly of the conglomerates to become propor- 

 tionally less northwards. On the other hand a considerable 

 thickness of Kuttung strata may have been removed by 

 denudation in the Gloucester District after their deposition 

 and before the Gloucester Coal measures were laid down, 

 as there is a considerable time and interval between the 

 two formations. This might account for the absence of 

 the Glacial Beds and perhaps of the Mount Johnson Beds, 

 but would not account for the absence of the Wallarobba 

 Beds which would normally underlie the rhyolites. These 

 matters cannot, however, be definitely decided until 

 detailed mapping is carried out in the intervening areas. 



IV. Relation of the Carboniferous formation to the 

 Devonian. — Unfortunately, no actual contacts between the 

 Devonian and Carboniferous strata have been found in this 

 district. In the northern part of the area shown in the 

 map (Plate XVIII) outcrops of the two formations almost 

 come into contact in the railway cuttings a short distance 

 north of the Avon River railway bridge, but this junction is 

 a faulted one, the Tamworth Beds here lying against the 

 Kuttung Series; the whole of the Burindi Series is missing. 

 In the western part of the map (Plate XVIII) a junction of 

 the Devonian and Carboniferous strata is shown running 

 parallel to the Barrington River on its western side, but the 

 position shown is only an approximation. Both the Devonian 

 strata and the lower Burindi Series are weak rocks and give 

 either very poor outcrops or none at all ; it is therefore, prac- 

 tically impossible to locate the base of the Carboniferous 



