OUTLINES OF GEOLOGY. 



35 



sulphurous and sulphuric acids, which are met with in the 

 neighbourhood of volcanoes, and muriatic and boracic acids. 



76. Of inflammable bodies of modern origin we may cite 

 sulphur, either sublimed from volcanoes or deposited in the 

 form of hydrate from springs charged with sulphuretted hy- 

 drogen, bitumen, naptha, and petroleum. 



77. Among metallic bodies it appears to be a well-estab- 

 lished fact, that the sulphurets of iron and copper are formed 

 on some occasions, among modern formations. We have 

 ourselves seen a vegetable petrifaction found in alluvium j 

 wholly composed of pyrites. Turf has also been found 

 containing pyrites. The blue phosphate of iron is also 

 formed under our eyes, but appears to be derived from the 

 white phosphate of more ancient date. 



The hydrated oxide, known as bog and meadow ore, to 

 the former of which we have referred in speaking of alluvial 

 formations, also belong to the modern period ; and with it 

 may be ranked the ferruginous pudding stones. 



78. The same organic remains which have been cited 

 under the head of Alluvium, are found in the newer chemical 

 formations. In those of more ancient date they are the same 

 as in the diluvium. 



ORDER III. DILUVIAL. 



79. Diluvial formations are coextensive with the surface 

 of the land, being found everywhere, except on the steepest 

 slopes, or in places within the reach of existing water-courses. 

 In the latter case they are not to be considered as wanting, 

 but are confounded with the deposits of alluvium. They are 

 made up of beds of mud, clay, marl, sand, and gravel, and 

 collections of boulders ; they include in some cases turf and 

 beds of fossil wood. The turf of diluvium does not exhibit 



