226 NERBUDDA DISTRICT. 



soon spread into lenticular layers, but several stood out, when fully 

 exposed, like the branches of a tree, irregular solid cylinders of green- 

 stone. These were apparently intruded into crevices formed in the 

 green mud bed, as it yielded to the force from below and shrunk from 

 the heat of the intrusive rock. 



A good case of the way in which minor offshoots strike out from the 

 D k • th M " principal mass of a dyke, is seen in the Sitariva 

 Section. River in Mopani, and occurs in connection with 



one of the dykes shown in the section represented in Fig. 8, page 169. 

 The river has excavated its channel in a direction at rig-lit angles to that 

 of the dyke, and exposed a good section of it in the bank. The dyke 

 intruded apparently from below, did not reach as high as the level of the 

 present surface of the ground, a continuous layer of the sedimentary 

 rock lies over the ridge of the dyke, but this is penetrated by numerous 

 small veins of various shapes and sizes, which the dyke below had pro- 

 jected upwards. 



Another and somewhat remarkable instance occurs on the course of 



this same dyke, and not far from the locality men- 

 Offshoot veins. . . 



tioned. Ine dyke, and the original rock are well 



exposed in plan. A small vein, never more than 2J inches wide, starts 



out from the side of the main dyke, from which 

 Remarkable case. . . 



it is never more than 4 inches distant, and paral- 

 lel to the side of which it runs for 21^ feet, when it again returns to, 

 and is lost in the parent mass, thus enclosing a narrow strip of the sedi- 

 mentary rock, 2\\ feet long, and 4 inches wide, and the line followed by 

 the little vein is quite independent of the bedding of the sandstone, here 

 a green earthy rock and nearly horizontal. 



Much might be said on the subject of the trap dykes of this district. 



_ , . ^ They are, as may be seen from our map, very 



Dyke in the upper J J r j 



Tawa Valley. numerous, and many of them from peculiarities in 



weathering, form striking and picturesque features in the landscape. But 



