182 PHYSICAL GEOGRAPHY. 



constitute many striking and picturesque groups of conical 

 peaks. Among these Mount Marcy rises 5,467 feet above 

 the tide; Mount M'Intyre, 5,183 ; Mount Seward, 5,100; 

 Mounts Martin and Santanoni, each 5,000 ; and Whiteface, 

 Taylor's Mountain, and Nipple-top are a few hundred feet 

 lower. These highlands extend into Canada, where they 

 form a mountain belt twenty-five or thirty miles wide, 

 along the sources of the Chaudiere and St. Francis.* 

 They are separated from the neighbouring districts of the 

 state of New York by the river and lake valleys named 

 above ; and, being impassable for an army, Lake Champlain 

 was the only route by which the Atlantic states could be 

 assailed from Canada East, or vice versa; — hence the 

 celebrity of its defiles in the annals of colonial and revolu- 

 tionary warfare. 



The valley of the lake is excavated in the lowest group 

 of the silurian rocks. The Potsdam sandstone, together 

 with a greenish-white marble, and a trap rock, are quarried 

 extensively at Whitehall, situated at the upper extremity 

 of the lake, for the double purpose of clearing sites for 

 houses, and procuring building stones. In various parts 

 of the lake shores, the silurian rocks are covered with beds 

 of clay and sand, in which there have been detected about 

 twenty species of marine shells, which exist in a living 

 state on the coast of the Atlantic at the present time. 

 The general character of the scenery, and especially of 

 the upper half of the lake, is bold, hilly, and picturesque, 

 often rocky, but occasionally cliffs of clay and sand 

 100 feet high border on the water. The shores are low 

 and shelving only in the bays, which are formed by short 

 lateral valleys. 



* Orford and Sutton Mountains are each reckoned at more than 

 4,000 feet high. The latter is the summit of a wide hilly tract, com- 

 posed of chloritic and micaceous schists and gneiss. — Hunt. 



