l82 NEW YORK STATE MUSEUM 



somewhat cut by cupholes. The edge of a still older, upper ter- 

 race, which Lake Valcour was destroying, may be seen directly 

 above the head of the figure. The old steamboat dock is hidden 

 in the second cove beyond the boat. In plate 19 we have a view 

 in this region taken farther to the north and near the" position of 

 the old steamboat dock. Another glacial basin, partly filled with 

 rock debris, is here shown. The rock boss at the right of it has 

 not yet lost its glaciated outlines although freezing water has de- 

 tached one block from its surface and the movement of shore ice 

 has drawn it a little outward. We have here a practically unbroken 

 glaciated outline reaching from low to high water. While the lake 

 was yet above its present level the side of this boss facing the 

 lake must have lost the sediments with which it may have been 

 covered. Its surface has been exposed to the action of solution 

 throughout the age of Lake Champlain. While the movement of 

 loose material on this surface has destroyed glacial striae yet such 

 striae may be seen on surfaces at the same level just south of this. 

 There are places here that have not lost 5 millimeters from their 

 former polished surfaces and we are obliged to limit the solvent 

 power of the lake waters to a figure at least as low as our estimate 

 made from the study of the pebble taken from Cystid point. If one 

 is still in doubt as to the correctness of this estimate let him exam- 

 ine again the west side of Spoon island as shown in plate 4. The 

 unbroken glaciated surface shown there runs from below lowest 

 water to above highest water After allowing for loss of surface 

 at the hands of various agents active here, what will you have left 

 for simple solution? The well developed caves of plates 1 and 10 

 lie between 60 and 180 meters from this face and on the same level. 

 Wha,t part has solution, at the hands of Lake Champlain, played 

 in their formation? 



Before leaving this question of solution we should call more 

 definite attention to an agent we have but mentioned, and that 

 is the influence of living or decaying green algae, sponges and 

 micro-organisms. If we again examine plate 9 we may note 

 that this surface of the Lowville block has a border of dentpits 

 which distinctly show the effects of differential solution brought 

 about by the above cause after the block had fallen from its bed. 

 Nearer the center of the block there was not light enough to sup- 

 port plant life and the dentpits of this region have suffered but 

 little change though there are a few thin seams of less solvent 

 material running through the block that have here formed very 



