28 BULLETIN OF THE NATURAL HfSTORY SOCIETY. 



in common a number of peculiarities, they were probably 

 injected from the same molten magma, and approximately 

 at the same time, the variation being due to segregation. 

 The dark minerals in the granite are biotite and horn- 

 blende in about equal amounts in the fresh parts of the 

 rock. But the biotite is an unstable mineral when near 

 the surface, and tends to alter to hornblende, or epidote, 

 so that we often find these minerals replacing it and still 

 retaining the outward form of their original. These, in 

 turn, when at the surface, are acted on by rain and 

 changed to soft green aggregates of chlorite, calcite, etc. 

 Scattered in small quantity through the rock are minute 

 crystals of the rare zircon, which can be separated by 

 crushing and " pamiing out," and show under the micro- 

 scope very perfect crystal forms. 



The contact between the granite and surrounding 

 rocks is usuall}'- hidden. ISTcar King's mill, Fairville, it 

 is exposed by a small quarrj'- in the limestone, and 

 here the lime is whiter and more crystalline near the 

 granite, and close to it contains great numbers of garnet 

 crystals. Besides these evidences of contact-metamor- 

 phism, there is between the lime and the granite a narrow 

 band of a peculiar rock like a " veir.-granite," which w\as 

 probably deposited by the heated water around the edge 

 of the intrusion. Further east, near Pleasant Toint, the 

 river has left some remnimts of the surrounding rock 

 clinging to the side of the granite cliif ; and here, too, 

 the limestone and gneiss are coarser than usual, and 

 garnet is developed, sometimes forming entire layers of 

 the rock. 



Gabhro. — Another type of intrusive rock appears in 

 two little knobs at Indiantown, and in a larger one mak- 

 ing the hill just north of Dolin's Lake, back of Rothesay. 



