lOO NEW YORK STATE MUSEUM 



as a mass and was quite unbroken, but on the north and south ends 

 the ground was intersected by fissures, " making the surface to 

 resemble the irregular fragments of a floe of ice left by the tide 

 upon a sloping shore." In regard to the cause of the subsidence, 

 Mr Dwight expresses the following view : 



There was then a tongue of land of considerable tenacity, a 

 few feet thick at the lower end, and 75 at the upper, resting upon 

 a very mobile and smooth clay ; the erosion of a shallow channel at 

 the creek, afforded a passage for the exit of this clay; and the 

 great and principal force which caused the fracture was, in m)^ 

 judgment, one acting in a perpendicular direction, as shown from 

 the fact, first, that the fracture is a sharp, perpendicular well- 

 defined line, and not the ragged, irregular sloping line usually seen 

 where the soil has been simply drawn down a declivity; second, 

 that immediately after the fracture, the thickest and heaviest portion 

 did sink and forced the blue clay before it, outward, and upward, 

 at the lower levels ; its own lateral motion being very small. 



Stockport. The occurrence of a landslide near Stockport, 

 Columbia county, on March 6, 1908, was communicated to the 

 State Geologist by Mr C. R. Van de Carr of that place, and the 

 writer was detailed to make an inspection of the conditions which, 

 from the details supplied, appeared to be rather remarkable. An 

 account of the disturbance was published in the Report of the 

 Director of the New York State Museum for 1908, from which 

 the following abbreviated description is taken : 



A section of the bank of a small tributary of Stockport creek 

 that empties into the latter opposite Columbiaville, with a vertical 

 elevation of from 60 to 75 feet, forming part of the 100-foot 

 terrace at this point, cracked along two parallel planes about 50 

 feet ap^rt as a maximum, and the included mass dropped down about 

 40 feet, measured on the outer fractured plane. This plane had a 

 slope of 80° toward the ravine. Its appearance and the adjacent 

 margin of the faulted block is shown in plate 3. The walls of the 

 second fracture, about half way down the slope, were inclined 

 away from each other owing to the tilt of the sunken block toward 

 the bank and the uplifting of the abutting clay beds in the bottom of 

 the ravine. A gap fully 15 feet wide was thus produced (see 

 plate 4).. The uplifted section included the stream bed that in 

 this way was so obstructed as to cause the waters above to form 

 a pool. 



The clay beds exposed to view were little broken up by the 

 movement; in fact they behaved much as solid rocks might have 



