56 5. W. McCALLIE 



original diameter. The matrix or binding material, which consti- 

 tutes only a small percentage of the pebble beds, consists mainly 

 of mica. Where the mica is absent or nearly so, the quartz pebbles 

 are frequently found welded together for the greater part of their 

 length; however, a slight pressure is usually sufficient to break the 

 bond without injury to the individuals. Each of the several pebble 

 beds examined consists of two kinds of pebbles, namely quartz 



Fig. I. — Bed of stretched pebbles near EUi jay, Gilmer County, Georgia. White 

 spots show feldspar pebbles not elongated. 



pebbles and feldspar pebbles. The former are by far the more 

 abundant and and are always greatly elongated. The feldspar 

 pebbles, on the other hand, are never 'elongated, but still retain in a 

 more or less perfect degree their original rounded shape. The feld- 

 spar pebbles, which are partially kaolinized, are well shown in 

 Fig. I, where they appear as rounded white spots. 



The chemical analysis of one of the pebbles by Doctor Edgar 

 Everhart, chemist to the State Geological Survey, here given, shows 

 it to be orthoclase feldspar: 



