liY II. I. .JENSEN rO 



Cretaceous sediments occur occasionally in the Ipswich Coal 

 Measure area, but only as very small localised lenticular patches 

 which represent deposits formed in lagoons or river-channels. 

 In Cretaceous times the drainage must have been from east to 

 west. Further faultino;, as between C and D, has led to the 

 compression of some parts, leading to the intense folding and 

 overthrusting at Ipswich. 



Some processes of this kind must have given rise to the struc- 

 tures observed between the Brisbane schists and the Darling 

 DoNvns. 



Another point worthy of comment is that, with the exception 

 of the Brisbane River, all the wateicourses in S.E. Queensland 

 roughly follow the structural lines, such as faults, anticlinal axes, 

 &c., and run N.N. W,-S.S.E. or N.-S., or more rarely N.N.E.- 

 S.iS.W. Such is the case with the Brisbane and Bremer Rivers 

 abo\ e Ipswich, the Logan and Albert, Deebing Creek, the Stanley 

 River, &c., &c. These streams are all subsequent. A somewhat 

 recent elevatory movement in part of this area has effected 

 certain changes in the drainage; Mr. Wearne informs me that 

 old river-channels filled with sand and gravel sometimes interrupt 

 the w^orking of a coal seam. 



Most of the valley of the Bremer Riv^er presents the features 

 of mature erosion. Likewise the Teviot Valley is mature, except 

 for a small part where it receives Woollaman Creek and Undallah 

 Creek as tributaries. Here it flows through hilly country, and I 

 consider this region to have been slowly and recently elevated, 

 river-erosion having kept pace with elevation. It is a strange 

 thing, which cannot be explained on other suppositions, that the 

 watershed between the Bremer and Teviot is almost in old age, 

 whilst all the Teviot's tributaries flow for a short distance through 

 rugged hilly country, even those which rise in the perfectly mature 

 area. It is evident that the Brisbane River is a fairly young 

 stream as regards its lower course. It is only just entering upon 

 its mature stage ; but many of its important tributaries are 

 mature. The nature of the beds through which they flow partly 

 accounts for this, the tributaries carving their valleys in soft 



