March, 190r.] THE TICTORIAN NATURALIST. -[97 



GEOLOGY AND PALEONTOLOGY. 



By G. B. Pritchard, F.G.S., Lecturer on Geology, 6^<^., 

 Working Men's College, Melbourne. 



One of the first difficulties to the beginner in geology 

 is a proper conception of geological time ; but as he be- 

 comes better acquainted with Nature and her methods he 

 begins to obtain a better appreciation of the magnitude 

 of past events in our earth's history, and soon gives up 

 the absurd idea of wanting to measure everything iii:; 

 years. The question is, however, always being asked of 

 the poor unfortunate geologist to state a definite number 

 of years for his periods of time, and occasionally an 

 extra-considerate individual will say, '' I don't mean to 

 within a thousand or twO' years, but I would like to have 

 some idea in approximate round numbers." 



Let us glance, then, first at one aspect of man's history, 

 say, for instance, in Ancient Egypt, and we find relics 

 and inscriptions which carry us back in all probability 

 some 8,000 or 10,000 years, and yet even this is very far 

 from the origin of man and the beginning of his history, 

 which must be placed still further back in time. 



Turning to another aspect, glance at some of the 

 changes in the crust of the earth which have been wrought 

 by natural agencies, such as wind and water, during what 

 is called " recent " geological time, and we see enor- 

 mously greater inscriptions and sculpturings than any 

 ever left by man. Niagara Falls, for example, shows its 

 past history very clearly, and the eating back of its 

 7 miles of gorge has been closely investigated, and time 

 estimates made of from 6,000 to 8,000 or more years. 

 But there are much greater works of nature than this of 

 recent geological date, and vast periods of time must 

 be allowed for their development. 



The geologist then finds it convenient to gi^'e up vears 

 of reckoning, and he divides the rocks which make up 

 the crust into three divisions, according to the groups of 

 animal and plant remains found in some of the strata or 

 layers of those rocks, as Palaeozoic (ancient life) or Pri- 

 mary, Mesozoic (middle life) or Secondary, Cainozoic 

 (recent life) or Tertiary. 



These terms, however, only give the headlines, and 

 further subdivisions are necessary to give us sufficient 

 rungs for our ladder of time. Thus we have the follow- 

 ing table : — 



r Recent 

 Cainozoic Pleistocene 



or i Pliocene 



Tertiary Miocene 



. Eocene. 



