Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/149

 Rh of the serpentine, as if they had been destroyed in consequence of the disintegration of the rock, and carried of by the waters.

In what formation then, ought we to place the serpentine of the Lizard? does it belong to the older formation of Werner, or to that which is more recent? the distinctions are in my opinion so vague, that I am almost led to suspect, that the terms are designedly obscure, is order to avoid being more explicit in the definition. Notwithstanding that obscurity, I think I can understand so far, as to discover that the characters by which it is endeavoured to distinguish these two formations, are erroneous, or imply a contradiction, and that if they are followed literally, we shall not in the present instance be able to refer the serpentine of the Lizard, either to the one formation or to the other.

The oldest formation according to Brochant, is found in the vicinity of gneiss and of mica slate, is mixed with granular limestone, and sometimes this last even predominates. It appears from what Brochant adds respecting the great extent of the newest serpentine formation, that the oldest is of least extent. Brongniart says, that the oldest formation seldom rises to a very great height, and in noticing the pot stones and the beds of iron ore (Fer oxidulé) found in the newest formation, he gives us sufficiently to understand that they are not found in the oldest; he also states, that the newest serpentine occurs in masses or balls, but does not say, whether this is the form in which the oldest is found. Kirwan says, that although the oldest serpentine is not metalliferous, yet it contains magnetic iron, and veins of copper.