^66 Dr A. Bone's Observations on 



coloured with red oxide of iron, so tliat they present to the eye 

 a very singular and sterile a^ect. The marly or argillaceous 

 inclined strata at their base, a^e partly violet and reddish, and 

 contain small veins of micaceous iron ores. In short, this locality 

 of serpentine may be considered as illustrating the elevation of 

 that rock from below, in the same manner as porphyry and the 

 accompanying breccia intimate the violence of the action. 



The position of the serpentine of Tuscany has already been 

 ably described by Brongniart, although not in a complete man- 

 ner, as that distinguished observer has omitted to notice several 

 accompanying interesting phenomena. For instance, in the 

 Valley of Garignola, the serpentine and diallage rock or eupho- 

 tide, not only cover a part of the limestones and marls, which 

 are converted into reddish jaspideous rocks ; but they rise 

 through them, and extend over them on all sides, so that they 

 have the shape of a wedge-shaped bed, or that of a mushroom. 

 The breccia formed of limestone and diallage rock, which 

 Brongniart places above the jasper, does not occur every where ; 

 but only in those places where diallage rock comes in contact 

 with broken and bruised marls and marly limestone. The 

 limestone is then sometimes changed into a granular mass. In 

 Austria, about one hour'^s walk from Waidhofen, on the nor- 

 thern side of the Ips, there is a hill of serpentine apparently 

 resting upon the same marly sandstones and marls as occur in 

 Tuscany ; and not far from it, there are in those slates which 

 contain fossil ferns, beds of bituminous and slate coal, which are 

 regularly worked. The lowest part of this deposite probably 

 belongs to the independent coal formation. 



If our acquaintance with these more recent serpentines be in- 

 creasing, geologists have not yet fixed the age of the serpentines 

 placed amongst slaty crystalline or primitive rocks. In this class, 

 are generally enumerated the following masses : — the serpen- 

 tines of Shetland (Jameson), and of the North Cape (Buch) ; 

 the bed-like veins of Portsoy (Jameson), and of the Lizard 

 Point in Cornwall; the great zone of serpentine of the depart- 

 ments of Arveiron, Lot, Correze, and Upper Vienne ; the hil- 

 locks of| serpentine and diallage rock in the talc slate of western 

 Liguria, and of the base of the Piedmontese Alps ; of the Alps 

 in the department of the High Alps (Brain<;on, Villard, St 



