about a mile from the lake shore. The stream also makes a 

 greater inimber of turns in this part of its eourse, thus 

 furnishing sections which extend in different directions. The 

 widening" of the gorge in this ])ortion is due to lateral plana- 

 tion or undercutting" in the soft shales, which causes the 

 upper shales and calcareous beds to fall down. This de- 

 struction of the banks is materially advanced by the very 

 perfect development of joint fissures which traverse all these 

 rocks and which allow the separation of the shale and lime- 

 stone masses after they have been undermined by the stream. 

 Such of the fallen material as comes within the transporting" 

 power of the current, is carried away, and only the larger 

 rocks remain. (See Plate XI.). These may accumulate in 

 such numbers at the foot of the cliff as to form an effectual 

 protection against the current when the amount of under- 

 cutting will be reduced to a minimum. The foundations for 

 a talus thus laid, rock fragments broken from the cliffs by 

 frost and heat will slide down and accumulate, and finalh^ 

 the sloping bank is produced, which from the decomposition 

 of the rock becomes soil covered and overgrown with 

 vegetation. In this manner a talus may form even though 

 the stream keeps close to the base of the cliff as in Section 7. 

 (Plate XII. ). In Section 6 a talus would probably be formed 

 were it not for the fact that the blocks of Encrinal limestone 

 are carried away for building purposes. Ordinarily, how- 

 ever, the cliff' is kept free from such accumtdations as long as 

 the stream keeps close to its base. But if the deflection of 

 the current transfers the cutting zone to another jiortion 

 of the stream bed, the cliff' will rapidly be degraded by 

 atmospheric action, a heavy talus will accumulate, and 

 vegetation growing upon this talus \vill com])letely hide the 

 underlying" rock. 



As will be noted by reference to the map (Plate II. I the 

 talus is best developed ui)on the inside of the bends, where 

 deposition, rather than erosion takes place, while the banks 



