562 W. C. PHALEN 



evidence of recrystallization. The molecular readjustment necessary 

 to obliterate all traces of strain may have occurred while the rock 

 was deeply buried, for it is almost certain that many of the phenomena 

 associated with the rocks of the region could only have been produced 

 while under very heavy load, i.e., while deeply buried, or subjected 

 to great pressure, or both.' But it seems that recrystallization by 

 solution and redeposition is as adequate and as safe an explanation. 

 That the rocks contained water is certain. The presence of muscovite 

 and biotite as secondary minerals, and the evidences of the sedi- 

 mentary origin of the rocks, all point to the former presence of water. 

 The amount of water present may have been small, as the presence 

 of large quantities of water to bring about such molecular changes 

 as postulated above is not essential.^ 



In sections cut parallel to the length of the quartz masses, there 

 are also evidences of crystallographic continuity, the larger part of 

 the sections extinguishing in a given position. Finally in all the sec- 

 tions studied cracks were observed running parellel to the major 

 axes of the cross-section and also parallel to the length of the quartz 

 masses. 



i CONCLUSION 



As a result of the studies made by the writer, it is concluded that 

 there is no necessity for assuming the former presence of original 

 quartz pebbles to produce the pencillate or pebble structure, or 

 lens-shaped masses of quartz described above, for, as pointed out, 

 the more perfect examples of the structure have been found resulting 

 from quartz veins. That elongations in true quartz pebbles may 

 occur and the results exactly resemble the structures figured above, 

 is so obvious as hardly to necessitate mentioning here. The structure 

 is regarded as essentially due to a peculiar cleavage combined with 

 flow cleavage (recrystallization). It is quite likely that it may be 

 produced in any rock and the simpler, the more resistant, and the 

 more homogeneous the material, perhaps the more perfect the result- 

 ing structure. Such structures on a much larger scale have been 

 observed by Mr. Arthur Keith of the U.S. Geological Survey, a 

 few miles west of Canton, Ga. They are figured in the acconipany- 

 ing illustration (Fig. 6). The country rock here is a talc schist, and 



I C. K. Leith, "Rock Cleavage," Bull. U.S. Ceol. Survey, No. sjg (1905), 69. 



