Plate 5. — Detail of Trap Ridge east of Greenfield. 



Photograph of the south face of the large boulder seen as a black surface in plate 

 .4. The rounded and angular blocks are trap, and they are enclosed in the sand 

 and glass mixture, which often shows fluidal structure. 



Commencing to the right of the watch-chain, which is to be seen in the lower 

 left-hand corner of the picture, and continuing upward for twice the length of the 

 chain is a series of four rounded blocks connected by narrow necks and sending 

 out narrow, angular lobes — forms which can not have resulted from explosions 

 throwing masses of lava into the air. The effect of the pile of great round blocks 

 with comparatively small amount of interstitial matter can only partly be given by 

 the photograph. 



(82) 



