16 NEW YORK STATE MUSEUM 



Spillways and the flat rocks 



The most singular feature of the surface in the towns of. 

 Altona and Mooers is the occurrence of large tracts of the 

 Potsdam sandstone, exceeding 12 square miles in area, barren 

 of glacial drift. These bare areas are not entirely valueless, 

 for the reason that in -the proper seasons a large yield of huckle- 

 berries is obtained from these tracts. In the year 1902, $4000 

 worth of this fruit was sold by one concern alone from gather- 

 ings on the Flat Rock southeast of Altona. 



The Altona Flat Rock is the largest of these barren tracts. 

 Two very small and probably originally continuous bare areas 

 known as Moose and Jericho rock occur at an elevation of about 

 1500 feet on the hillside southwest of Jericho. Southwest of 

 Cannon Corners, extending on the unmapped area west of this 

 sheet for the distance of about a mile and a half to the south, is 

 Blackman's rock. Northwest of Cannon Corners and beyond 

 the limits of the map is another tract known as Stafford's rock, 

 north of which along the international boundary line is another 

 area marginal to and extending west from " the Gulf," an 

 abandoned river gorge and waterfall [see pi. 5]. 



Between Sciota and West Chazy, at elevations ranging from 

 2(50 feet to 500 feet above the sea, are small but noticeable areas 

 of the Potsdam sandstone, from a quarter of a mile to half a mile 

 across, bare of drift. The latter occur in the zone of wave 

 action following the disappearance of the ice, the drift is not 

 very thick about their margins, and their occurrence does not 

 appear to demand a special explanation. It is different, how- 

 ever, wiih I he larger areas lying above the 600 foot but mainly 

 between the 700 foot and 900 foot contour lines; a system of 

 bared rock surfaces which extends with slight interruption 

 from the Canadian border on the north across the present lines 

 of drainage around the northern slope of the Dannemora massif 

 to the head waters of the Little Chazy river. With this system 

 " the Gulf" on the boundary line near Covey hill is intimately 

 connected. 



To l)r Gilbert belongs the entire credit not only of looking 

 for and finding these features, but also of having explained them. 



