Physical Geography. 151 



deposition of the limestone may account for the total 

 absence of fossils in the larger part of the formation. 

 Whether or not the water was too salt for the healthy 

 production of numerous shells and corals, is a question 

 I have not yet attempted to solve, being in the mean- 

 while content to prove (as I think) that the waters 

 formed inland lakes, that lay in a large continent which 

 began in Old Eed Sandstone times, but had undergone 

 many modifications in its physical geography before the 

 Permian lake-basins came into existence. 



