654 Harshberger: Plant formations of Nockamixon Rocks 



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esses to fruition in such an excessively dry soil. There must be 

 considerable water in the rocky strata beneath, because here and 

 there in the ravines In the driest summer weather, water Is seen 

 oozing out wdiere the water-bearing seams are exposed. Various 

 hepatic mosses, true mosses, and several other plants remain green 

 in such spots, while many other plants of the drier chff faces, 

 having long since perfected their flowers and fruits, have dried up 

 completely, all but their underground parts, which are reserved for 

 perennation. 



GEOLOGIC CHARACTER OF THE CLIFFS 

 The American New^ Red rocks extend across Bucks County 



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They are penetrated by eruptive dikes of trap 



rock w^hich in our region form Haycock Mountain on the one hand 

 and the celebrated Ringing Rocks on the other, while a crescent- 



FlGURE 2. Nockamixon Rocks, Bucks County, Pa. General view of clififs, 

 canal, and Delaware River, lookingr east. 



shaped mass just back of the edge of the chff at the time of its 

 appearance probably altered the original color and texture of the 

 surrounding Mesozoic red shales. In the center of the horse- 

 shoe shaped trap there is apparently a small trap hill on a higher 



