FLOOD SILT OF THE HUNTER AND HAWKESBURY RIVERS. 193 



In 1903 Mr. J. H. Maiden, f.l.s., read a valuable paper on 

 mitigation of floods in the Hunter River, dealing with 

 the matter from the point of view of the forester. 1 



With regard to the allu vials of the Hawkesbury River 

 the information is at present somewhat meagre, at any rate 

 from a geological point of view. One of us (Acting Pro- 

 fessor Guthrie) 2 has published a report on its soils in which 

 a rough map is given showing the approximate extent of 

 these allu vials; this map being reproduced from an earlier 

 one in this Journal by one of the authors (Professor David). 3 

 The Geological Survey of the Department of Mines, Sydney, 

 has lately issued a geological map of the coastal plain near 

 Sydney, in which the above sketch of the ailu vials has been 

 reproduced. The allu vials do not form a typical delta, for 

 they terminate 30 miles in a bee line from the coast, the 

 channel of the Hawkesbury below Richmond being bounded 

 by steep slopes and terminating in the fiord of Broken Bay. 



III. — Area of the Hunter Delta and Character of 



its Deposits. 

 The Hunter River is tidal from its mouth at Newcastle to 

 the Falls above Belmore Bridge, West Maitland, a distance 

 of 41 miles following the river, and about 18J miles in a 

 bee line. The alluvial plaius subject to flood are about 

 35,000 to 40,000 acres in extent. 



This area is, however, only about one-third of the total 

 area of the Hunter Delta, the greater part of the delta 

 lying to the north-east of a line running from Stockton to 

 Sandgate and thence to Raymond Terrace, being covered by 

 blown sand which places the old flood silts out of reach of 

 the agriculturalist. These flood silts in the lower part of 



1 Journ. Roy. Soc. N.S. Wales, Vol. xxxvi., pp. 107 - 131. 



2 The Chemical Nature of the Soils of N. S. Wales, with special refer- 

 ence to Irrigation, by F. B. Guthrie, f.i.c, f.c.s., Journ. Roy. Soc. N. S. 

 Wales, Vol. xxxvn., pp. li. -lxv. 



3 Journ. Eoy. Soc. N. S. Wales, Vol. xxx., pp. 1 - 69, pis. i. - iv. 



M— Oct. 5, 1904. 



