THE WOMBAT. 



in soil and subsoil has produced a corresponding change in 

 the flora. A couple of miles further on we get into the timber,, 

 and any one who, knowing the district, will look at the 

 geological map will see that the edge of the timber has been 

 taken as a geological boundary by the surveyors. But a 

 change in the flora means a change in the fauna. Fresh 

 plants afford a source of food to new forms of insects, and the 

 insects again will bring new forms of birds. 



The geologically most isolated area near Geelong is 

 that occupied by the Dog Rocks. This small area of about 

 a square mile in extent is in the main occupied by granite- 

 Its soil differs both chemically and structurally from that of 

 the country round it. To a superficial observer the sandy 

 soil may appear the same as that which we have noticed near 

 Spring Creek, but it is in reality very different, being richer 

 in certain salts, such as potash, derived from the gradual 

 waste of the granitic rock. Besides this the differences in the 

 subsoil make the underground drainage different, and thus a 

 different series of plants and consequently of animals is found. 

 The soil is not so rich as that of the country to the north- 

 west nor that forming the plateau across the river, but the 

 close texture of the lava of these areas produces imperfect 

 subsoil drainage that is unsuited to the growth of trees.. 

 Whereas here on the Dog Rocks we find, as we do in all but 

 our more mountainous granitic areas, an open park land 

 well suited for grazing, but for little else. 



Now, it is well in a society or club to have some definite 

 aim in view, and to attempt some piece of work which holds- 

 out some prospect of definite results being attained within a 

 reasonable time ; moreover, it should be one in which as many 

 different branches of study as possible are represented. It is 

 here then that the Dog Rocks affords a field on which it 

 would be well to concentrate all the forces at the disposal of the 

 Club. It is so near at hand that it can be visited again and 

 again at all seasons of the year ; its area is small and its 

 differences from the surrounding country are striking. Now, 

 would it be possible for a " Dog Rocks Natural History Com- 

 mittee " to be formed to take the subject up ? Work can be 

 found among birds, reptiles, insects and plants. Perhaps 

 some of the smaller marsupials may be found which have 

 been killed off elsewhere in the neighbourhood. A careful 

 search will disclose a few minerals new to the district, while 

 there are numerous characteristic views of granitic weather- 

 ing worthy of study, and which should attract the attention 

 of the photographers. Let each member keep to his own, 

 branch and make his collection and notes as thorough as he 

 can. A definite aim instead of desultory observing will have 

 a considerable effect in raising the status of the club, and will 

 be excellent mental training for its members. 



