SECONDARY LIMESTONE. 



&r where this limestone presents the shape 

 bodies as irregular as granite or serpentine. 

 This loss of the stratified form is sometimes so 

 complete throughout a given mass, that no traces 

 of it are visible ; but, in other instances* it is easy 

 to perceive, that the beds lose their regularity in 

 a gradual manner, and that a shapeless mass is 

 thus continuous with a collection of the most 

 regular strata. It is further important to remark, 

 that, in these cases, the organic bodies which are 

 contained in the shapeless rock, are commonly 

 very obscure and ill defined, and, very generally, 

 rare ; while it is also sometimes easy to perceive, 

 that in those instances where a regular series of 

 beds gradually loses its form, the organic remains 

 undergo similar gradual changes, till, at the end, 

 they sometimes entirely disappear. 



Under the same circumstances, such lime- 

 stories undergo an alteration of appearance and 

 texture. The dark varieties change their colour 

 to some lighter tint; and, in this manner, black 

 strata have been observed to become gradually of 

 a pure white. The soft earthy varieties, in the 

 same cases, become compact, or even crystalline ; 



