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NEW YORK STATE MUSEUM 



before the slip. The ultimate source of strain which gave rise 

 to the Assuring may be found in a possible undermining of the 

 upper beds by underground flowage. 



The pressure exerted by the fall of the block was communicated 

 by the semiliquid clay to the beds next to the stream which were 

 raised up and shoved a few feet to the south. The volume of 

 the displacement was estimated roughly at between 4000 and 5003 

 cubic yards. 



There can be little basis for connecting the slip with a move- 

 ment in the underlying Hudson River shales, though such a rela- 

 tion might be suggested by the known occurrences of postglacial 

 faulting in the region. A rock fault at all commensurate to that 

 observed at the surface would have had far-reaching effects, and 

 even a slight dislocation, such as would supply merely an impulse 

 in precipitating the mass of clay already in delicate equilibrium, 

 could scarcely have happened, for it would have been accompanied 

 by earth tremors of sufficient magnitude at least to have been 

 detected by the seismograph at Albany. 



In this connection it may be noted that the slip occurred within 

 a short time after the heavy earthquake of March 26th in southern 

 Mexico. The transmitted vibrations from the earthquake were 

 registered at Albany beginning at 6.10 p. m. Though they were 

 of exceptional magnitude, it would hardly seem justifiable to infer 

 any direct relation between the two phenomena. 



The writer is indebted to Mr H. P. Whitlock for the accom- 

 panying illustrations and to Mr C. R. Van de Carr, on whose prop- 

 erty the landslip occurred, for information and courtesies extended 

 during his visit to the locality. 



