146 Dr. Fitton on ilie Geology of Australia. 



the calcareous matter that surrounds it*. But, wherever the 

 imbedded fragments in the latter consist of lime-stone, their 

 union with the cement is complete. 



Rottnest Island, about four hundred and fifty miles south 

 of Dirk Hartog's Island. — Indistinct specimens containing nu- 

 merous fragments of shells, in a calcareous cement; the sub- 

 stance of these shells has at first sight the appearance of cal- 

 cedony, and is harder than ordinary carbonate of lime. 



The characters of the shells in Captain King's specimens 

 from this place are indistinct ; but the specimens at the Jardin 

 du Roi, which, there is reason to suppose, have come from this 

 part of the coast, contain shells of several species, — belonging 

 among others to the genera, corbula, chama, cardium, por- 

 cellanea, turbo, cerithium. M. Prevost, to whom I am in- 

 debted for this account, observes, that notwithstanding the re- 

 cent appearance of the shells, the beds which contain them are 

 stated to occur at a considerable height above the sea: and he 

 remarks that the aspect of the rock is very like that of the 

 shelly deposite of St. Hospice, near Nice. 



King George's Sound, on the south coast, east of south 

 from Cape Leeuwin. — Beautifully white and fine quartzose sand, 

 from the sea-beach. Yellowish gray granite, from Bald-head. 

 Two varieties of a calcareous rock, of the same nature with that 

 of Dirk Hartog's Island; consisting of particles of translucent 

 quartzose sand, united by a cement of yellowish or cream- 

 coloured carbonate of lime, which has a flat conchoidal and 

 splintery fracture, and is so hard as to yield with difficulty 

 to the knife. In this compound, there are not any distinct 

 angular fragments as in the stone of Dirk Hartog's Island ; 

 but the calcareous matter is very unequally diffused. 



A third form in which this recent calcareous matter appears, 

 is that of irregular, somewhat tortuous, stem-like bodies, with 

 a rugged sandy surface, and from half an inch to an inch in 

 diameter; the cross fracture of which shows that they are com- 

 posed of sand, cemented by carbonate of lime, either uniformly 

 mixed throughout, or forming a crust around calcareous mat- 

 ter of a spongy texture; in which latter case they have some 

 resemblance to the trunks or roots of trees. — A mass, which 

 seems to have been of this description, is stated to have come 

 from a height of about two hundred and fifty feet above the 

 sea, at Bald-head, on the South Coast of Australia. These 

 specimens, however, do not really exhibit any traces of organic 

 structure; and so neai'ly resemble the irregular stalactitical con- 

 cretions produced by the passage of calcareous or ferruginous 



* Captain King informs me that the soundings in this part of the coast' 

 bring up a very fine quartzose-sand, like that cemented in the breccia. 



solutions 



