SIXTH REPORT OF THE DIRECTOR I909 29 



or that, the secondary silica has of itself been less resistant to 

 atmospheric decomposition than the primary vein quartz of 

 which the pebbles are apparently constituted. Yet it is not 

 necessary to regard this secondary deposition as a large factor 

 in cementation. Indeed cementation here has chiefly been 

 effected by secondary crystal growth of the constituent pebbles. 

 Some investigators have thought that the conglomerate pebbles 

 displayed general evidence of etching under the action of organic 

 acids. The eye is attracted at once by the glistening surface of 

 these pebbles, reflecting the light from a multitude of facets, 

 and these facets are all of crystal growth. Indeed pebbles are 

 easily found wherein this crystal enlargement has gone forward 

 to almost complete construction of the simple prism and pyramid 

 with the original rounded pebble visible as a nucleus. This 

 enlargement is general throughout the deposit and implies room 

 between the pebbles for such growth; hence a very loosely 

 cemented mass chiefly now held together by the locking of the 

 secondary deposit. This general condition of weakness has been 

 the cause of breaking down the rock beds wherever there are 

 lines of slight resistance; thus principally along the almost rect- 

 angular series of vertical joints the dissolution here resulting in 

 quadrate blocks standing like masses of floe ice floating on the sea. 



Again easy passage through or between the strata has weak- 

 ened and undermined the support of the blocks so that they 

 have been tilted over at various angles. Thus the picturesque 

 chasms, the sunken grassy walks, the rock bridges and the danger- 

 ous clefts are to be accounted for. 



Examination of the original quartz pebbles under the crust of 

 secondary growth shows sufficient evidence of the dynamic 

 strains to which they were subjected in the formation of the 

 rock masses from which they were derived, but of the geo- 

 graphical origin of these pebbles, what land it was that furnished 

 them and by what lines of transportation they were brought 

 hither are problems still remaining to be solved. 



Supposed gold sands of the Adirondacks. The past year has 

 witnessed a recrudescence of interest in the alleged gold-bearing 

 sands of the Adirondacks. This office is frequently called upon 

 for information on this subject, as well as for an expression of 

 opinion regarding certain enterprises which have been inaugurated 

 for the purpose of working such deposits on a commercial basis. 

 The occasion seems opportune, therefore, to publish a general 

 statement for the consideration of those who may have little 



