408 NATUKAL HISTORY. 



in banks superincumbent on chalk beds, frequently mixed 

 with Kalkspath* and Hornstone. The globules compos- 

 ing it are sometimes very minute and fine, at others, 

 coarse and granular. Peastone or Pisolite differs only 

 from Oolite in the larger size of its particles, which are 

 composed of concentric laminae. 



Iron Roestone, also one of the Oolitic group, com- 

 posed of chalk and marl, is rough, of a bluish-gray color, 

 and consists of sprinkles of lenticular globules, contain- 

 ing much iron ; it is also called Clay Ironstone ; very 

 hard. Found largely in Germany, Poland, and Russia. 



Lias Gryphite Limestone (Magnesian Limestone 

 of England) , consists of dark-colored strata or layers, in 

 which an argillaceous character (nature of clay) pre- 

 dominates, but is also remarkable for a quantity of cal- 

 careous matter mingled with the clay, and particularly 

 distinguished by the fossil remains of numerous Gry- 

 phites. 



Lias Sandstone, is a yellow and brown sandstone, 

 found in alternate layers with limestone and marl. Both 

 of these strata contain bitumen and naptha, which flows 

 through them ; pyrites, bisulphuret of iron, and sulphur 

 springs are also present in this formation. This bitu- 

 minous fluid, also called animal oil, found in the Lias 

 strata, is of great importance at the present time, and 

 useful in the manufacture of gas, being supposed to be 

 the product of millions of perished marine animals, whose 

 oily portions are now used in this form to light up our 

 chambers and our streets. Naptha affords both fuel 

 and light to the inhabitants of Badku, on the Caspian. 



Jura Dolomite, or Bitter Spar, is remarkable as con- 



* Calcareous Spar. 



