363 



PRIMARY LIMESTONE. 



OUR information respecting this rock, from 

 geological writers, is not only scanty, but has 

 been rendered very obscure by the establishment 

 of the transition class. It is impossible to disco- 

 ver which of the limestones, described as belong- 

 ing to this class, appertain to the primary rocks, 

 and which to the secondary ; and hence it is dif- 

 ficult to give any satisfactory information respect- 

 ing the geological characters of the limestone 

 now under review, except that which is derived 

 from observations made in this country. 



No evidence on this subject can be received, 

 short of that which is founded on its alternation 

 with rocks acknowledged to be primary; al- 

 though cases may be imagined in which, by 

 forming the uppermost of the primary strata, it 

 might be in contact with the lowest secondary 

 sandstone. As the presence of organic remains 

 in some of the argillaceous schists of this class, is 



