XEPHELEXE-EOCES IX BEAZIX. 



467 



centimetres from the immediate contact. Unfortunately I was 

 unable to ascertain whether or not the same phenomenon is presented 

 along the upper contact, as the places where it had been exposed 

 were either decomposed or covered up by slides of the overlying 

 red rock. 



Above the tunnel, for a distance of 5 or 6 kilometres, the cuttings 

 (with the exception of those in the red rock and leucite-rock already 

 mentioned, and situated close to the tunnel) are mainly in phonolite, 

 generally much decomposed, and of no special interest. In one a 

 dyke of phonolite is seen, cutting a mass of decomposed foyaite, 

 showing that if a part of the phonolite ( as in the case of that 

 enclosed in the red rock and the conglomerate near the foot of the 

 mountain) is older, or (as in the case of the peripheral portions of 

 the mass at the tunnel, of the dyke in conglomerate above mentioned 

 and of the rock described below) contemporaneous with the foyaite, 

 a part also is newer. A cutting about 2 kilometres below the 

 Cascata station shows inclusions of foyaite in bluish phonolite, some 

 of which are of considerable size. These present sharply defined 

 outlines, and are either circular or show a tendency to mimic poly- 

 gonal crystalline forms. The next cutting above, which is through 

 a broad low ridge of foyaite, exhibits exactly the reverse inclusions, 

 that is to say, of phonolite in foyaite. 



This rock, which is apparently identical with that of two quarries 

 off from the line of railway near the Cascata station, and almost in 

 a straight line with the cutting, the furthest being at least a mile 

 away, presents several interesting characteristics. The rock in the 

 main resembles quite closely that of the tunnel, but contains a 

 glassy honey-yellow ingredient, which has not been noticed else- 

 where. It is also marked by indistinct circular spots slightly 

 darker in colour than the generality of the rock, as if drops of oil 

 had been sprinkled over it. In places also the nepheline, which is 

 generally bluish, takes on a rather brilliant red colour, and appears 

 to present more distinctly marked crystalline forms. Small points 

 and thin irregular lines and, in one case, a pear-shaped inclusion 

 two inches long, of an amethystine colour also appear. The most 

 interesting of its peculiarities, however, are the inclusions. Some 

 of these are irreeular masses more coarsely crystalline than the 

 enclosing rock, which, owing to the predominance of large crystals of 

 felspar, have something of the aspect of pegmatite. Others are 

 pebble-like masses of liner-grained and darker foyaite, while others 

 again, and these are the most common, are of phonolite. These are 

 of all sizes up to that of a man's head, with sharply denned and 

 generally angular outlines, though without the mimicry of crystal- 

 line form presented by the reverse inclusions of foyaite in phonolite. 

 The smaller inclusions, often no larger than the end of the thumb, 

 are perfectly homogeneous in appearance ; but in some of the 

 larger ones there is a more or less distinct mixture of granitic and 

 felsitic material. Two of the largest inclusions seen are here 

 .represented (figs. 5 and 6). 



