

SIW 



' * 



stder the form of the surrounding ground, and lo judfe 

 whether any lake could have probably existed on its site. 

 In tome cases, indeed, we may still detect a portion of 

 the original lake, surrounded and continually lessened by 

 the advancing peat (Fig. 79). It is easy to see that at .1 







. : 





comparatively recent period the aspect of these tracts of 

 country must have been very different from what it is 

 to-day. Ireland, for example, must have been an 

 island of shallow lakes instead of peat-bogs. Under- 

 neath the peat a layer of fresh-wa may frequently 

 be found full of MU h typically lacustrine shells as 

 Lymntt^ /to/*//*,;, rUimtrbis, and Cvdas. These under- 

 lying layers should always be diligently searched for bones 



