March, 1907.] THE YICTORIAN NATURALIST. 203 



The above will serve to give a very fair idea of the 

 general appearance or fades of this particular horizon in 

 our tertiary rocks, and when a similar set of fossils is 

 obtained elsewhere we are justified in correlating them 

 to the same horizon. Subsequent to the deposition of this 

 series, and after the lapse of some little time, a shoaling- 

 of the waters gradually took place, and then further 

 deposition of, more generally speaking, a shallower water 

 series of younger date, as represented by the Beaumaris, 

 Sandringham, and Brighton beds. This series has been 

 referred to as miocene, but here, again, a difference of 

 opinion exists ; hence the use of the term, Kalimnan is 

 preferable. The beds yield a distinctive set of fossils, 

 and can be readilv discriminated from the Balcombian. 



GEOLOGICAL HISTORY OF THE COUNTRY 

 AROUND PORT PHILLIP. 



By T. S. Hall, M.A., Lecturer and Demonstrator in 

 Biology, Melbourne University. 



There are very few places more favorably situated than 

 our camp at Momington for examining rocks of varied 

 geological age, although in the short time at our disposal 

 we shall not be able to see many of them. As it is im- 

 possible to tell the ages of rocks in years, geologists speak 

 of them by their relative age, and for convenience of 

 reference have divided past time into a series of 

 " periods." In history we might, to some extent, dis- 

 pense with dates, and remember that certain events took 

 place during the reign of a certain sovereign. Then, 

 knowing the order of the sovereigns' reigns, we should 

 know the relative times at which events occurred. Lawyers 

 speak of Acts of Parliament in this way, and they know 

 that an Act of Anne's reign was subsequent to one of 

 Elizabeth's, without quoting actual dates. Similarly, the 

 geologist kno'ws that a rock of silurian age is older than 

 one of Jurassic age. The lawyer learns the sequence of 

 the kings from written history ; the geologist sees that, of 

 two sedimentary rocks in the same cliff-face, the lower one 

 is the older. Then he examines the fossils in the two 

 rocks, and so knows these rocks again wherever he may 

 meet them. They are branded unmistakably by their 

 contained fossils. Names, then, such as ordovician, 

 Jurassic, eocene, need disturb us no more than Ethelred, 

 or Marv, or those of any other sovereign. 



I 



