REPORT OF THE DIRECTOR I915 lOI 



acted in similar circumstances. The main scarp was clean-cut and 

 the sunken block held together in a body. 



The cause of the disturbance was ascribed at the time to the 

 presence of a layer of water-soaked liquid clay which came to the 

 surface in the very lowest part of the ravine and upon which the 

 upper bed rested in a state of delicate equilibrium, ready to be 

 precipitated by some impulse. It was thought this may have been 

 supplied by the weakening of the structure through cracking, as it 

 was noticed that a longitudinal crack had developed along the bank 

 shortly before the disturbance occurred, which was during the 

 night. With increase of pressure upon the liquid layer the latter 

 sought escape at the lowest outlet, whereupon the whole block 

 came down at once. The sudden exertion of pressure upon the 

 liquid layer upraised the beds in the ravine but not to an extent 

 that could be considered proportionate to the volume of the sub- 

 sidence which was estimated at from 4000 to 5000 cubic yards. 

 An interesting circumstance, of no significance probably with 

 respect to the cause of the disturbance, was the occurrence of a 

 heavy earthquake in Mexico, the vibrations of which reached 

 Albany at 6.10 p. m., the same date. 



The vicinity of Stockport bears evidences of having been the 

 scene of numerous slides of the terraced clays. Another section 

 of the same bank is reported to have subsided since the occurrence 

 here described. 



Hudson. A disturbance of serious proportions took place 

 August 2, 19 1 5, on the property of the Knickerbocker Portland 

 Cement Co., just outside the city of Hudson. In some features 

 it was the most remarkable of the recorded landslides in the Hudson 

 valley, as it undoubtedly has been the object of more thorough 

 inquiry than any previous disturbance in this section. Although 

 many employees of the company were within the zone of dis- 

 turbance at the time (shortly before 6 a. m.), few, if any, could 

 give a connected account of the succession of events, so rapid and 

 overwhelming they appeared to the senses. The company immedi- 

 ately instituted an investigation into the causes of the catastrophe, 

 which in addition to large property damage involved the death of 

 five workmen and injuries to many more, most of whom were 

 caught in the wreckage of the power house.^ 



iFor description of the general effects of the slide, see the Engineering 

 Record, August 7, 1915. An account of the geological and engineering 

 features was published by the same paper in the issue of August 28, ipiS- 



