GEOLOGICAL FAULT AT KURRAJONG HEIGHTS. 363 



jong Heights on November 19th last, and found conclusive 

 evidence of the existence of a slight fold and strong fault 

 at the "Out Rock." Later on, December 12th — 15th, 

 Mr. E. F. Pittman, Assoc, r.s.m., and I made a cursory examin- 

 ation of the country for over 12 miles westerly from the 

 Kurrajong Heights as far as the top of Mount Toman and 

 northerly from the Kurrajong for over five miles to the 

 " Mountain Lagoon." We ascertained as the result of this 

 examination that the downthrow was not restricted to the 

 immediate neighbourhood of the fault but that the whole 

 strip of the Blue Mountains between Kurrajong Heights 

 and Mount Tomah had subsided, the western edge of the 

 4 senkungsfeld ' being bounded at Mount Tomah by an 

 easterly monocline and the eastern edge by a fault and 

 slight western fold (See Section on Plate 16). Later, with 

 a view to determine the throw of the fault more accurately 

 it was decided to remeasure it, and Mr. G. H. Halligan, 

 L.s., f.g.s., very kindly surveyed the fault with me with a 

 chain and theodolite on January 1st, 1903. The results of 

 these observations may now be given. 



Details of Section from Richmond to Mount Tomah. — 

 Only brief reference will be made here to the above, as 

 they will be given fully in the Geological Survey Memoir, 

 to appear later. 



Richmond is situated on a plain of brick red sandy soil, 

 about 60 feet above sea level. This deposit is of fluviatile 

 or lacustrine origin. The highest modern floods in the 

 Hawkesbury do not come nearer than within 10 to 12 feet 

 (measured vertically) of its summit. It would be interest- 

 ing to ascertain whether in tlie Richmond District, as at 

 Maitland, this red soil deposit is underlaid by ' raised 

 beaches ' of estuarine origin. The red soil alluvial plain 

 has been terraced by the Hawkesbury River, and the 

 modern loamy alluvial plain has been deposited in the eroded 

 hollows in the older alluvials. 



