404 THE JOURNAL OF GEOLOGY. 



covered, this negative evidence would have its value, as it would 

 indicate that the physical conditions were not favorable to life, 

 and an explanation for this fact might be found. It is scarcely 

 necessary to mention that care should be taken not to mistake 

 the shells occurring in modern swamp deposits associated with 

 the ancient beaches for true lacustral fossils. 



About the borders of the present lakes and sometimes even 

 below the level of the lowest of the ancient beaches the remains 

 of the mastodon, elephant, giant beaver, elk, bison, deer, etc., 

 have been found. The recency of the existence of such of these 

 animals as are extinct may thus be established, as well as the 

 former distribution of those still living in other regions. 



Evidence of the existence of man has been reported from 

 one of the old lake ridges in New York, and it is important that 

 this interesting discovery should be sustained by evidence from 

 other localities. Stone implements especially should be looked 

 for in undisturbed lacustral clays, and in the gravels of the 

 ancient beaches. 



The remains of forests have been stated to occur in the lacus- 

 tral clays adjacent to the south shore of Lake Erie. It is desir- 

 able to know the extent of these deposits and how continuous 

 they are ; also the character of the plant remains they contain, 

 and whether they have been disturbed from the position in which 

 they grew. Some of the questions that may be asked in this 

 connection are : Was the basin drained and forest covered before 

 the vegetable remains were buried, or were the plants floated to 

 their present position, or did they grow on moraines covering the 

 stagnant border of the retreating glacier and become involved 

 and buried in morainal material as the ice melted ? 



6. Life in the present lakes.- — The fauna of the present lakes 

 has a bearing on their past history, for the reason that in the 

 deeper parts of lakes Superior and Michigan crustaceans and 

 fishes have been found which are believed to be identical with 

 marine forms. These may be considered as " living fossils," 

 and are thought by some to indicate that the lakes in which they 

 occur were formerly in direct communication with the ocean. If 



