Featherstonhangh^s Geological Report. 



5b 



SO' to about 54° 30' north latitude. In that countiy the mass 

 of the deposite consists of a blue claj, somewhat bituminous 

 and exceedingly pyritiferous, containing numerous courses of 

 iron stone and septarious nodules. Arenaceous limestones 

 and beds of sandstones are enclosed in this, and, towards the 

 bottom, very characteristic beds of pure blue and white lime- 

 stones, useful as lithographic stones. This structure of the 

 mass gives it an external appearance, which distinguishes it 

 so much from all other formations and groups that it is impos- 

 sible to mistake its characters. But the surprisingly interest- 

 ing organic remains w^hich are entombed in it, and which will 

 be hereafter alluded to, have established its still more general 

 character, wherever it has been observed. I have not seen 

 any thing resembling it in any part of the United States.* 



It will be evident to all who consider the general structure 

 of the oolitic series, that it could not have escaped observa- 

 tion had it existed within those parts of the United States 

 which are known to geologists ; for, taking it as a mass, as it is 

 found in Europe, where, from local causes perhaps, some of 

 its members are irregularly distributed, it presents three dis- 

 tinct argillo-calcareous deposites of a mean thickness of about 

 five hundred feet, alternating with other deposites of a cal= 

 careous and sometimes arenaceous structure. These three 

 argillaceous masses are the lias, the Oxford clay, and Kimme- 

 ridge clay, and the causes which deposited them have been so 

 general as to have been simultaneously in action in England, 

 France, and Germany. 



* I do not know whether the writers on American geology (Silliman's Journal, 

 Oct. 1835, Jan. 1836,) who still continue to describe various members of the car- 

 boniferous limestone as the equivalent of the lias, have ever been in Europe and 

 have examined the lias beds there. I should think not. Having had sufficient 

 opportunhies of comparing the ilmerican localities referred to, with the lias in 

 various parts of Europe, I can but repeat that the characteristic fossils of the lias 

 have not been seen here, and that the mineral affinities of the American beds in 

 question, as well as their fossils, class them beyond a doubt in the carboniferous 

 limestone. 



