REFORT OF THE DIRECTOR AND STATE GEOLOGIST f68 



tion. This part of the rock is more properly an arkose than a 

 sandstone. As these rocks were formed from the ruins of the 

 pre-Cambrian rocks, their composition indicates much only 

 partially decomposed material on the old land surface, and 

 some of the very coarse conglomerates exhibit very coarse ma- 

 terial of this kind, only slightly water-worn, as if protected in 

 an old hollow of the surface. 



There is much conglomerate in the basal Potsdam of the 

 Mooers sheet but by no means so coarse, or so extensive, as in 

 many other places. But the basal red beds are more widely 

 exposed than in any other part of the Adirondack region. On 

 the north and west of Rand hill there is much thin-bedded, deep 

 red rock which disintegrates easily, and is interbedded with 

 harder and firmer bands of massive red sandstone. These rocks 

 give rise to a deep red soil by their rapid breaking down. The 

 harder beds furnish an excellent building stone, not so flinty and 

 of a deeper red color than the well known stone from Potsdam. 

 These beds seem to mark the extreme base of the formation in 

 this vicinity. They are so extensive and so different from the 

 usual coarse base of the Potsdam that there has been some ques- 

 tion in the writer's mind as to whether they properly belong with 

 it, but. aside from their somewhat different lithologic character, 

 no evidence for or against this view has been forthcoming. 



On the west side of Rand hill, surrounded by pre-Cambrian 

 rocks on three sides and with their extent to the southwest 

 hidden by the heavy moraine covering in. that direction, are two 

 outliers of these red beds, which gave the writer the idea, in his 

 earlier and more hurried survey, that the Rand hill pre-Cambrian 

 rocks were nearly or quite surrounded by the Potsdam. But 

 diligent search in the woods of western Beekmantown resulted 

 in the discovery of three small exposures of gneiss, sufficiently 

 separated to show clearly the absence of the Potsdam. Thes^ 

 outliers are at the same elevation as the corresponding beds 

 farther north, no sign of faulting was discovered, and they are 

 believed to occupy old depressions in the pre-Cambrian surface, 

 as Kemp believes similar outliers in Essex county 1 to do. 



^emp, J. F. Bui. geol. soc. Amer. 



