CrsiiiNG — Geolo(;v of Clinton County. 



559 



Series VI. The widespread sand deposits of the Saranac, form here, as 

 in Schuyler Falls, the most conspicuous feature of the Pleistocene deposits. 

 Away from the river in the northwestern part of the tow n, heavy morainic 

 deposits come in above the level of the sand plain. 



Beekmantown. 



Series I to III. The only Pre-Cambrian outcrop in Beekmantown is 

 found on Rand's hill, a wide northeast and southwest ridge running from 

 western Beekmantown into southern Altona. On the east and south, a heavy 

 mantle of drift covers the flanks of the hill, concealing the extent of the rocks 

 in those directions. The ridge is made up, for the most part, of anorthosite 

 which is flanked on both sides by gneiss. On the east is a microperthitic 

 gneiss of brown color, which contains both green nionoclinic pyroxene and 

 hornblende. On the west the only gneisses shown are basic, very schistose 

 hornblende gneisses, both with and without pyroxene. 



The main interest attaching to the anorthosite here is due, in the first 

 place, to its distance from the main body of that rock ; and, in the second 

 place, from the information it gives regarding the character of the surface on 

 which the Potsdam was deposited. At the present time the hill is entirely 

 surrounded by Potsdam, with the possible exception of a strip half a mile 

 wide. The summit has an elevation of 1,500 feet, w hile the Potsdam on the 

 west side runs up to 1,400 feet, and we are certainly justified in assuming 

 that at one time the whole hill must have been covered by the sandstone, 

 quite probably to a considerable depth. 



The exposures of the anorthosite in Beekmantown are by no means 

 as good as in Altona, and the rock will be described in the report on that 

 township. Those in Beekmantown are of quite typical anorthosite, but the 

 rock is not fresh. 



Series IV. Potsdam sandstone. The only outcrops of this rock seen 

 in the township are along the road over Rand hill, and closely adjoin the 

 anorthosite on the west. The exposures are tolerably frequent, but very- 

 poor and the only rock seen is of the red, feldspathic, easily disintegrating 

 variety. Except for a gap one-half mile wide, occupied by hornblende 

 gneisses, the Potsdam exposures are practically continuous along the west 

 side of the anorthosites, and the road is reddened throughout the larger 

 part of its length, by the degraded rock. No conglomerates w ere seen. 



East of Hand hill, the very heavy drift- covering completely hides all 

 rock from view till the Calciferous exposures in the central part of the town 



