322 



Prof. T. G. Bonney. On the 



[May 5, 



does not appear to agree with this mineral (though aecnrate measure- 

 ments are difficult to obtain) for it seems markedly oblique. 



It is evident at a glance that this rock has been subjected to a great 

 pressure normal to the conspicuous foliation. The garnets have been 

 cracked and crushed out, so- as to have become elongated ovals in 

 shape. A glance at the diagram will render a more minute descrip- 

 tion needless, and will show that the garnet was more or less flattened 

 out before it broke. The quartz grains also are cracked, being some- 

 times only a little, sometimes much displaced. This mineral, however, 

 does not appear to have been so completely crushed up as in the Tau 

 Tetnuld schist. Occasionally a small grain, adjacent to the (original) 

 felspathic constituent, has escaped altogether. The felspar has, I 

 I elieve, often been crushed out, and then converted into the above- 

 named microlithic mineral. The larger mica flakes are twisted about 

 in the manner usual in a rock which has been crushed. Study of 

 this slide seems to me to show conclusively that this rock, anterior to 

 the crushing, was a moderately coarse crystalline rock, consisting 

 chiefly of quartz, felspar, biotite, and garnet, probably a rather mica- 

 ceous gneiss. 



Garnet, squeezed out and cracked ; surrounded by biotite, quartz and the fibrolitic 

 mineral, x 25 diam. 



Guluku (D). — A small fragment of a micaceous granitoid rock. 



Except for the greater abundance of biotite and the smaller amount 

 of quartz this rock is closely allied to the next described ; the felspar 

 is a little more decomposed, and small garnets are rather more 

 numerous. With these modifications the description given below 

 applies here, and this rock, too, has evidently undergone about a similar 

 amount of mechanical disturbance. Another small fragment from 

 about the same level contains more white mica, but as the general 

 aspect suggests no important difference, and it is not a very promising 

 specimen, I have not had a section made. This occurs at a slightly 

 lower level than (B), and the two are about 100 feet below (A). 



