356 NEW YORK STATE MUSEUM 



not showing. It is capped by red, feldspatliic sandstones of the 

 ordinary basal type. The conglomerate carries numerous quartz 

 pebbles, up to 2 inches in diameter, along with occasional smaller 

 ones of diabase, and of red orthoclase feldspar, the latter clearly 

 from pegmatite veins. The coarsely granular matrix looks black 

 when fresh, becoming green mottled with blotches of chloritic 

 material on weathering. Along with the quartz in the matrix 

 is much microperthite feldspar, considerable magnetite in streaks, 

 and occasional grains of titanite and microcline, all these grains 

 being isurrounded hy a greenish, chloritelike cement, whose exact 

 nature is not clear. 



This conglomerate represents an intermediate stage between 

 the normal, quartzose conglomerates and the local, disintegra- 

 tion conglomerates of the hollows. It is therefore of interest 

 to note that, while it lies in contact with anorthosite gabbro, 

 with no gneissic outcrops within a mile, it is entirely made up of 

 gneissic debris. This may either argue transportation of the 

 materials for at least this distance, which would imply great 

 strength of wave action; or else that gneiss occurred near at 

 hand along the old shore, became covered up by later Potsdam 

 beds, and has since been faulted out of sight. There is no ques- 

 tion about the necessary fault being near at hand, and, so far 

 as the writer knows, no evidence which will enable a decision 

 one way or the other." 



Very abundant also in the basal piortion of the formation, 

 are beds of rapidly disintegrating, very red, coarse arkose sand- 

 stones, made up mainly of quartz and feldspar grains and the 

 whole much permeated with red hematite. They break down 

 rapidly to a red, sandy clay, a characteristic soil which is pro- 

 duced by no other rock in the district, and which often shows 

 the presence of these beds when actual outcrops are lacking. 

 Beds of this sort often occur interbanded with the basal con- 

 glomerates, or they may constitute the larger part of the base, 

 conglomerates being scarce or absent, as is the case on Band 

 hill, where these beds show greater bulk than in any other 

 known locality. 



Well indurated, red sandstones, such as those from the type 

 locality at Potsdam, are not infrequent in the basal portion of 



