i8I8.) ON THE FORMATION OF ROCKS. 273 



they are found either on or near the surface of the earth, 

 and their origin is within the Hmit of our observation: as 

 nature may be said to carry on her manufactory, subject to 

 the daily inspection of our senses. They have been call- 

 ed alluvial rocks, by some mineralogists. 



Second Order of Neptunian rocks. 



12. Coal formation, including the attendant strata of Pud- 

 dingstone, Sandstone, Slaty Clay, Bituminous and 

 Alluminous Strata, &c. with vegetables, and other 

 impressions of organic matter. 



i3. Gypsum, coarse grained, composed of shells, and 

 other organic matter, witS all its attendant strata of 

 indurated Marie, Sandstone, cellular, and other depo- 

 sitions of silex, &c. &c. 



14. Limestone, coarse grained, composed of shells 

 and other organic matter, with all its attendant strata of 

 indurated marl, sandstone, cellular and other deposi- 

 tions of silex, &c. 



15. Chalk, including all the attendant substances, as sili- 

 ceous depositions of flints in strata and nodules, py- 

 rites, &c. with shells and other organic matter disse- 

 minated, &c. 



16. Compact Limestone, including every species of ho- 

 rizontally stratified limestone, with the remains of 

 organic matter, as shells, &c. &:c. disseminated. 



17. Sandstone, including all horizontally stratified sand- 

 stone, having organic matter, or alternating with strata 

 including organic matter. 



18. Pudding stone, including every species of rock formed 

 of rolled masses horizontally stratified, having organic 

 matter, or alternating with rocks including organic 

 matter. 



