4 JOURNAL OF THE 



counties, and the exact time at which the disturbance 

 took place which resulted in the formation of these 

 massive g^ranitic dikes is, as jQt, a matter of doubt. 



So numerous are these dikes in certain places, and so 

 long- have their feldspars been underg-oing- surface 

 transformation into residual kaolin or clay, that one 

 mig-lit expect to find in this reg'ion, as in some other 

 countries, sedimentar}^ deposits of this material which 

 had been transported for greater or less distances; but 

 when we bear in mind the gfeneral elevation in the 

 mountain-reg-ion and the consequent rapidity of its 

 streams, we can readily understand that this product 

 of denudation would scarcely be deposited until it had 

 been carried so g-reat a distance from the original source 

 as to be lost by comming-ling- in the lowlands with 

 larg-er proportions of other and different materials. 



Along- the borders of the Piedmont plateau-reg-ion 

 there are occasionally found deposits of this kaolin 

 material which has evidently been carried but a short 

 distance. Such occurrences are more extensively known 

 on the western border of the Coastal Plain reg'ion, 

 mainly in the Potomac formation, as in the neig-hbor- 

 hood of i^iken, S. C, and Augusta, Ga., and in many 

 other places, where considerable deposits of this kaolin- 

 material occur, both in the form of arkose (where the 

 kaolin is still mixed with the quartz and mica of the 

 original granitic formation) and in the clay-beds, where 

 it has been more completelv sorted, and the kaolin has 

 been separated from the coarser materials, so as to 

 form extensive beds of what is locally termed "china"- 

 or potters-clay. In some cases, in the arkose material 

 just referred to, the partially decayed crystals of feld- 

 spar are frequently- found with the kaolinization in- 

 complete; and mingled with these are fragments of 



