NOTES ON THE POINT HOPE SPIT, ALASKA 189 
inlet on account of the danger of the ice-pack over-riding the spit in 
winter.. 
It will readily be seen that a solid ice-pack six or eight fathoms 
in thickness, which would be of sufficient thickness to ground a little 
distance off the shore of the Point Hope spit, would be a most effective 
agent in ridging or piling up in front of it and shoving shorewards 
the unconsolidated gravels and sand at the bottom, under the influence 
of pressure from the south. Such a grounded ice-pack driven by 
the combined pressure of heavy south winds and the north-setting 
current as the pack starts north in summer undoubtedly plays an 
important réle in the growth of the spit by shoving the sands and 
gravels of the bottom up within the limits of effective wave action. 
The pack no doubt acts similarly at times in bringing materials up 
on the northwest shore, but it has already been pointed out that at 
present destructive agencies are more effective on that side of the spit 
than are the combined constructive agencies. 
