120 DOMAIN IX. ANOMALOUS. 



Alps, whose vertical position led to his theory of 

 refoulements. 



A shell of the cockle kind, as already men- 

 tioned, has in one rare and solitary instance been 

 observed in one of the pebbles ; and in another, 

 imbedded in the cement of the stone ; which 

 might, in the language of Werner, indicate that 

 it is a transitive, if not a secondary rock. But 

 this would not argue against its coetaneous 

 formation, any more than the shells found in 

 jasper, and many siliceous substances. 



The varieties of this curious rock are almost in- 

 finite; and it is diversified with almost every shade 

 of colour, except perhaps pure blue and green, 

 the former of which does not occur even in the 

 finest jaspers; but the latter, which is common 

 in that substance, may probably be discovered 

 when persons of real skill observe the sites of this 

 remarkable rock*. Agate only presents single 

 beautiful pebbles, of a more fine and waxy ap- 

 pearance, and often with more outlines; but 

 here numerous pebbles display such various ac- 

 cidents, that in a large polished slab no two 

 would be found exactly alike. Some have the 



* 1 am since informed, from undoubted authority, that the green, 

 exists. 



