PLATE VI II«. 



DETAILS OF TRAP EIDGE EAST OF GREENFIELD. 



I"iG. 1. — Photograph of the south face of a "large bowlder at the foot of the clifl' below the quarry. 

 The rounded and angular blocks are trap, and they are Inclosed iu 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 photograjih. See page 431. 



Fig. 2. — Enlargement of the part of fig. 1 which lies to the right of the watch in the photograph. 

 A band of the sand and glass mixture extends across from the upper right corner and 

 separates a large, rounded block above from a double block below, whose parts are 

 Joined by a narrow neck near the center, while the part to the right sends down a long, 

 curved lobe into the breccia below. This shows one of the forms which can not have 

 been "bombs" in the ordiuary sense. .See page 431. 



426 



