D NOTES ON SURFACE GEOLOGY — BAILEY. 



upon the possible existence of "placer" deposits or alluvial dig- 

 gings along the course of old channels of drainage. A few 

 words may be added upon each of these points. 



(1). Over very considerable areas the covering of drift is 

 such as to completely conceal from view the underlying strata. 

 As already remarked, this is particularly true of the whin belts 

 along or in the vicinity of which the principal auriferous lodes 

 occur. This covering is often composed largely of boulders 

 which may be piled up in great heaps and often attain immense 

 proportions, but when these are less frequent, (for they are sel- 

 dom wholly absent), there are conmionly thick beds of coarse 

 gravel or, in the numerous depressions, extensive peat bogs and 

 barrens. The thickness of the superficial deposits is, in the 

 absence of kames, ordinarily about seven or eight feet, but may 

 be twenty feet or more, while the height of local drift ridges or 

 kames may be as much as one hundred feet 



(2). While these superficial deposits thus hide from view the 

 underlying rocks, and thus greatly enhance the difficulties of 

 the explorer and prospector, they may, nevertheless, be so em- 

 ployed by him as to lead the way to the discovery of lodes of 

 which otherwise he might never suspect the existence. I have 

 been informed that in the case of several of the most important 

 mines at Molega and Whiteburne, the first discoveries of gold 

 were made in quartz-bearing boulders, which were then care- 

 fully traced back to their parent source. From the nature and 

 origin of the drift these are naturally sought to the north of the 

 localities in which the boulders occur, and the distance travelled 

 has apparently usually been but slight, commonly not over half 

 a mile. In trenching or costeening the surface, trie quartz 

 boulders are found to increase in number as well as in size 

 as the lode is approached, and when this is passed, to suddenly 

 cease. They are also said to be invariably sharp and angular, 

 not rounded, and to be more deeply buried near the lode than at 

 points more remote from the lattei; Intelligent and practical 

 prospectors even maintain that they can recognize from baud 

 specimens of gold quartz the lead from which they were derived. 

 (3.) The larger parts of the superficial deposits of South- 



