8 FRANK D. ADAMS 
broken into by mining are found to be lined with beautiful crystals 
of pyroxene or other constituents of the rock. 
The other product of pneumatolitic action belonging to this class 
is a rock composed of an aggregate of small leaves of a very deep brown 
or black mica, and is less common. ‘These mica rocks almost invari- 
ably contain more or less calcite disseminated through them, which 
on exposure to the weather is dissolved out, the weathered surface of 
the rock thus being disintegrated into a soft mass of small scales of 
mica. ‘The chemical nature of this mica has not been determined, but 
it is probably a variety of lepidomelane, containing a considerable 
amount of fluorine and probably some lithia such as is found in lime- 
stones about granite intrusions in other parts of the world. 
The alterations of Class b, whereby the limestones are converted 
into amphibolite, are especially well seen about the borders of the 
great Glamorgan bathylith whose eastern limit lies in the township 
of Glamorgan. This bathylith here breaks through the great body 
of limestone underlying the northwestern portion of the township of 
Monmouth and affords a most excellent and striking example 
of lit-par-lit injection. The character of this contact action can 
be excellently studied at Maxwell’s Crossing, on Lot 15 of Range 
VI of the township of Glamorgan. Here the limestone, toward the 
granite contact, passes gradually over into amphibolite, the latter 
being undoubtedly produced by the alteration of the former. The 
invading granite in the form of apophyses wanders through the lime- 
stone series in all directions, sometimes cutting across the bedding, but 
very frequently in the form of narrow dykes forcing their way between 
the beds of the invaded limestone, changing it into amphibolite and 
presenting a typical instance of lit-par-lit injection. The granite, 
furthermore, not only penetrates the series, but floats off masses 
of the altered rock which, in the form of bands, streaks, and isolated 
shreds, are seen thickly scattered through the granite in the vicinity 
of the contact, and which, while less abundant, are found throughout 
practically the whole extent of this bathylith as mentioned below. 
The separate fragments of amphibolite where completely surrounded 
by the granite, while clearly nothing more than masses of altered lime- 
stone, are rather harder and more “‘granitized”’ in appearance than the 
amphibolite which is still interstratified with the limestone, and the 
