520 



DE. C. CALLAWAY ON THE ALLEGED COiNVEESIOls OF 



ground-mass of granite. For these mixtures of hypogene rocks, the 

 term " diglomerate " * may be suggested. 



Pig. 2. — Section of Granite in jointed Diorite. 



Letter sliinna. 



Some interesting facts in confirmation and expansion of the pre- 

 ceding observations occur in this hill, which lies two and a half miles 

 south-west of the last locality, and therefore much nearer the 

 granite massif. Lettershinna is a ridge running east and west in 

 accordance with the strike of the region. It is mainly composed of 

 granite ; but near and at the summit are some masses and blocks of 

 included diorite. 



On the north-western slope, I observed an oblong block of diorite 

 immersed in the granite. The fragment was about a yard long 

 and eighteen inches broad (fig. 3). The microscope shows the 



Fig. 3. — Section of Diorite in foliated Granite. 



hornblende of this diorite to be clear and well crystallized; but 

 the felspar is cloudy, and has apparently undergone partial decom- 

 position. At the distance of about a foot was a smaller block of a 

 roughly ovoid shape. That these are true inclusions, and not cross 

 sections of veins, may be seen a little higher up the hill. Here a 

 block of diorite is exposed in the face of a cliff, the foliation of the 

 granite curving round the block both above and below it. 



Near the summit of the hill the diorite occurs in larger masses. 

 Some of these are fringed by one or more outlying bands arranged 

 roughly parallel to the margin. In one place there were three of 



* " di-," because the blocks are forced asunder. 



