TIIK VICTORIAN NATURALIST. 33 



shifting dunes. The first two classes are generally well grassed, 

 while the latter are devoid of vegetation. Mr. C. S. Wilkinson 

 described one of the ridge-like dunes occurring near Cape Otway. 

 It runs parallel with the coast for about a quarter of a mile, at an 

 average height of 50 feet ; but a height of 300 feet has been 

 recorded for others. The landward slope of the dunes is much 

 steeper than the seaward. Mr. Wilkinson found the average 

 angle of steepest slope to be about 32 . A few observations by 

 myself gave an angle varying between 30 and 32 . In Victoria 

 the dunes do not extend inland for more than three or four miles, 

 but in Western Australia they extend in places for ten miles. 

 The sand of which the dunes are composed consists mainly of 

 broken fragments of shells with silicious particles. Under the 

 microscope the skeletal parts of corals, polyzoa, foraminifera, 

 and, according to Mr. Wood, echini spires and sponge spicules 

 can be distinguished. 



Warrnambool is situated on the southern coast of Victoria, and 

 various quarries and cuttings expose good sections of the under- 

 lying rocks. In most of these the rock is seen to be well bedded, 

 the beds being inclined, and at first sight the formation would 

 appear to be a sedimentary deposit. The stone is used for build- 

 ing purposes. When first quarried it is somewhat friable, but it 

 hardens on exposure. Under the microscope the material appears 

 to be identical with that of the dunes now being formed. Mr. 

 D. Avery, of Queen's College, Melbourne, has kindly made an 

 analysis of a sample of the stone for me, and has given the following- 

 composition : — 



Organic matter and water ... ... ... 5*88 



Alumina and iron oxide ... ... ... '26 



Silica ... ... ... ... ... ... 1 '43 



Carbonate of lime ... ... ... ... 92^43 



IOO'OO 



From this it will be seen that the rock consists almost entirely of 

 carbonate of lime. In the quarries the angle of dip is about 31 , 

 and the direction of dip is, generally speaking, at right angles to 

 the coast line ; but there are exceptions to this. In several places 

 I found the direction of dip easterly, or parallel with the present 

 coast line. Along the coast the cliffs afford good sections. Here 

 thinning out, false bedding and unconformities are noticeable ; 

 but the greatest angle of dip is the same as in the quarries — viz., 

 31 . The rock of the sea cliffs is much harder than that in the 

 quarries, a fact probably explained, in great part, by the exposure 

 of the former. No whole sea shells are met with in this forma- 

 tion ; but Professor Tate, of Adelaide, has, I believe, found 

 several species of land shells. The formation is confined to the 

 coastal regions, never extending more than a mile or two inland. 



