CLASSIFICATION OF MARLS. 



431 



^ j. 

 s jg 



M 



i 



1. Lime-stone proper. 

 . Marl-stone. 

 . Recent oyster or other hard sheila. 



I Stony I Marl . stone . 

 texture. \ 



fl. Chalk. 



2. Impure chalk. 



3. Travertin or calcareous tufa. 



4. Argillo-calcareous marl, or true 



marl (of mineralogists). 



II. Earthy 

 texture, 



or marl in 



general 



and in 



most ex- 

 tended 



5. Shelly sea-sand. 



6. Shell-marl. 



A. Fossil 



fresh-water 



shells. 



B. Tertiary 

 fossil sea- 

 shells. 



a. Sandy mi- 

 ocene marl. 



& 



b. Clayey mi- 

 ocene marl. 



f c. Calcareous 

 eocene marl, 

 with very lit- 

 tle if any 

 green-sand. 



d. Calcareous 

 matter and 

 green-sand, 

 both consi- 

 derable. 



e. Gypseous 

 or green- 

 sand earth, 

 with little if 

 any calca- 

 reous matter. 



