130 THE OLD BED SANDSTONE. 



twenty years there are few systems whose names, at least 

 have been more familiar to the ordinary reader. But sinci 

 Agassiz elaborated his monograph, and Miller penned hi; 

 sketches, more extensive information has been obtained 

 and it is the object of the present chapter to display tha 

 newer knowledge in an intelligible and attractive form. 



Arranging the rock-formations of the crust in chronolo 

 gical order, it will be seen that the Old Eed Sandstom 

 holds a middle place among the palaeozoic or primeval : 



Quaternary or Recent, . ' I CAINOZOIC. 



Tertiary, j (Recent Life.} 



Cretaceous or Chalk, . \ MESOZOIC. 



Oolitic or Jurassic, . V (Middle Life.) 

 Triassic Upper New Red Sandstone, J 



Permian Lower New Red Sandstone, "j 



Carboniferous, ., . . I PALEOZOIC. 



Old Red Sandstone and Devonian, j (Ancient Life.) 



Silurian, J 



Cambrian, | Eozoic. 



Laurentian, j (Dawn Life. ) 



It does not belong to the very oldest, whose rocks have 

 been rendered crystalline by metamorphism, and whose 

 fossils have been sorely obliterated, but it is still very an 

 cient, and hence the interest that attaches to its old-worlc 

 forms, the outlines of which and their habits of life th< 

 pen of the palaeontologist can for the most part restore 

 The composition and origin of its strata are, generally 

 speaking, of easy determination. Conglomerates that were 

 once pebble and shingle beaches ; sandstones and flagstones 

 resulting from shore-formed sands; concretionary and coral 

 line limestones chiefly of animal origin ; and shales anc 

 marlstones, the consolidated muds of the deeper waters 

 Here and there we have bituminous shales, partly of anima! 

 and partly of vegetable impregnation ; and at still wider in- 



