warped masses. Similarly for the upper Hawkesbury with 

 the Wollondilly horst to the west. The upland valley of 

 this river above Burragoraug is about 2,000 feet abovesea 

 level, the western horst being about 3,500 feet in height. 

 The same horst exceeds 4,000 feet a few miles east of 

 Bathurst, and the Bathurst Plains (2,500 feet) appear to 

 be a senkungsfeld dropped between the Orange and Sunny 

 Corner highlands. This interesting topographical feature 

 will be discussed in detail by Mr. O. A. Siissmilch in the 

 near future and is here mentioned only as one of the im- 

 portant block faults of eastern Australia. One portion of 

 the Hawkesbury River known as the Nepean, has had its 

 direction determined by the Kurrajong Fault and Lapstone 

 Hill Fold described by Professor T. W. E. David. 1 These 

 features also parallel the coast and their tectonic origin 

 has been determined by stratigraphic methods. 



Further north the Nandewars appear to be either a fault 

 or monoclinal fold carrying the highlands rapidly under the 

 Black Soil Plains. Tingha lies on a block warped down from 

 the Guyra horst, and Inverell lies on a block faulted off the 

 Tingha plateau, Middle Creek ravine shows the youth of 

 the faulting. The high plateaus of Guyra, Ben Lomond and 

 Guy Fawkes are upfaulted blocks, while the Armidale 

 plateau is a relatively depressed area. Guyra and Ben 

 Lomond lagoons appear to arise from warping action. Guy 

 Fawkes breaks away in several great steps (one called the 

 Dorrigo) to the sea. The upper surfaces of these horsts 

 are frequently covered with swamps representing the fill- 

 ing by waste of depressions due to warping. The high 

 country along the south arm of the Clarence in the neigh- 

 bourhood of Dundahra, Coombajha and Oooraldooral (west 

 and south of Cangai) marks the line of a long and powerful 

 fault. 



■ E., t 



