LANDSLIDES OF MT. GREYLOCK 5 I 7 



which fracturing so loosened the clay that it could be carried 

 away in suspension. This continued until a large quantity of 

 clay had been removed from a stratum immediately underlying 

 the surface sod. The most evident explanation for the slipping 

 of the clay and its uptilting in the stream bed is that a stratum 

 of blue clay rested on an inclined plane which was rendered 

 slippery by the water of the spring. This stratum was separated 

 from the surface sod by the washing away of the clay between 

 them. When it slipped it was stopped either by the former 

 rock bank of the stream or by some other obstacle, the slope 

 and weight being sufficient to push the clay up from the stream 

 bed and to raise with it the pier and part of the dam. 



After the last slipping the muddiness of the water was 

 greatly lessened showing that the movement of the ground had 

 almost ceased. Since then, however, the amount of sediment 

 in the water has increased, indicating that a further fracturing 

 is in progress. 



H. F. Cleland. 



WlLLIAMSTOWN, MASS. 



