528 H. S. JEVONS, H. I. JENSEN, T. G. TAYLOR AND C. A. SUSSMILCH. 



is evidence of the existence of the peculiar rim to the oval 

 dish-shaped sheet already mentioned in the first part of 

 this paper. 



In the northern part of the Reservoir Quarry, the main 

 rock is exposed well below the .great segregation veins, 

 and it is found to be comparatively free from segregation 

 veins of any kind. A few thin veins are to be seen, gener- 

 ally not exceeding 10 cm. in thickness, two or three of 

 which are parallel with the two great veins, whilst most 

 of them have no special orientation. There is no trace of 

 any other great segregation veins comparable with the 

 two just described. They would be easily seen even on 

 the most weathered rock if they existed. 



Between the great segregation veins there are a few 

 thin veins connecting them, running nearly at right angles 

 to them or more obliquely ; and these cross veins sometimes 

 swell into irregular masses of aplitic and pegmatitic 

 material. Above the great veins there are also numerous 

 smaller veins running in various directions. One of these, 

 averaging from 20 to 30 cm. in thickness, is larger than the 

 rest; it branches off the upper great vein near the middle of 

 the quarry face, runs upwards a little, and then continues 

 parallel with the junction of the shale, at a depth of 

 5 m. (16 ft.) below it. This vein finds its counterpart in a 

 somewhat similar vein lying at the same depth in the Emu 

 Quarry. The smaller veins are some of them parallel with 

 the junction, and the rest run very roughly at right angles 

 to it. It is worthy of note that the segregation veins 

 never penetrate into the most compact part of the pallio- 

 essexite, that is, within 2 m. (6 ft.) of the junction with 

 the shale, and the few which are found in the sub-pallium 

 to 4 m. from the junction are always thin. 



The thickness of the two great segregation veins is 

 variable ; indeed they are not regular sheets like the very 



