MUD ISLANDS, PORT PHILLIP BAY 133 



small scale chart, three islands are shown in their true positions ; 

 their outlines do not appear to differ from the chart published 

 later in 1859-60 (Fig. 1) surveyed by Commander M. G. H. W. 

 Ross assisted by Messrs. Turton, Sturgess and Deck and corrected 

 up to 1863. 



This last chart is the first to give a large scale outline of the 

 group — the natural scale is -gyAffir — an ^ is referred to here as 

 Ross's chart. 



In 1864, Commander Henrv L. Cox, assisted by Thos. Bouchier, 

 J. G. Boulton and P. H. McHugh, made the chart of Port Phillip 

 at present in use, and the basis of all subsequent corrections and 

 extensions. The natural scale is s&ooo " ^ox appears largely 

 to have accepted Ross's survey for Mud Islands. 



Physical Features. 



The outline of Mud Islands as delimitated by the Coast Survey 

 in 1916 and on Ross's chart of 1859-60 is shown in Fig. 1. It 

 will be seen that while at some places there is agreement, at others 

 there is considerable variation. The question arises, then, as to 

 what is to be inferred from these variations — whether they are 

 due to inaccurate charting or progradation and encroachment 

 during the last 80 years. Considering the difficulties in charting 

 the islands and the changes now in progress in Port Phillip, the 

 variations are probably attributable to both, and for convenience 

 of reference, Mud Islands is assumed to consist of four main 

 islands, none of which are named on the charts, but are known or 

 referred to here as Western Island (69 acres), Middle Island (51 

 acres), Boatswain's Island (98 acres), and Eastern Island. 

 Besides these there are some low banks, one of which, that between 

 the southern extremity of Western Island and Boatswain's 

 Island, is referred to as Low Bank (11 acres) (Fig. 1.) 



The islands are situated near the centre, of the Great Sand 

 (Murray's "shoal of sand") trending N.E. ; the Great Sand is a 

 little more than 5 miles long by 2-3 miles wide, and outside the 

 group is covered by from 1 to 7 feet of water. The depth increases 

 abruptly to the north-west as one approaches Symonds' Channel 

 which is from 20 feet to 55 feet deep ; to the south-west is South 

 Channel with 42 feet of water, and on the north east the southern 

 portion of the Inner Basin of Port Phillip. 



The Mud Islands group has been built up on the Great Sand at 

 the only place inside Port Phillip where consolidated dune-rock 

 is exposed above high water mark ; dune-rock is the surface rock 

 of the adjacent Nepean Peninsula to the south and east, and 

 partly of the Bellarine Peninsula to the south-west. In the Mud 



