(85 ) 
vation followed to a point about 180 feet above its present posi- 
tion. During this elevation erosion must have been especially 
active. Depression followed of about roo feet, bringing the 
level down to its present position. The same sinking is still 
slowly progressing. All these changes must have affected 
the Bronx, although they do not modify the main contention 
set forth above regarding the diversion. 
Attention may be drawn to the rocking stone near the 
southern border of Bronx Park, and at the spot shown on the 
map. It is a fine specimen of its kind. It is about ro feet 
wide by § feet thick by 7 to 8 feet high and may be rocked so 
that its North pole swings through about 3 inches of arc. 
