Winter operations, 1970-1971 / John C. Ayers, Norbert W. O'Hara, William L. Yocum.

shore ice structure, which is in accord with one of the modes of shore ice development presented by Marshall (1966). During late winter the Cook Plant site
develops a second frozen lagoon and a second outer ice barrier that are embellishments upon the basic shore ice structure.
At fullest (temporary) maturity the shore ice structure at the Cook Plant
site may consist of an icefoot composed of two ridges of onshore ice, a frozen
lagoon of ice floes, an outer barrier of ice, a second frozen lagoon, a second
outer barrier, and finally a transient field of floe ice of limited durability
but which reached a surprising extent of 10.5 miles on 2 February 1971.
The ice ridges and lagoons of the shore ice structure build up as frozen
spray, freezing slush, small ice cakes, ice balls, and sand from the bottom,
are all added at the lakeward edge of the ridge. In addition, snow is trapped
behind (shoreward) the ridges and solidified by spray coming over the ridge,
and windblown sand from the beach is deposited on and incorporated into the
ridges and lagoon ice. Except for windblown snow and sand, the accretionary
processes go on only on that ridge which is currently exposed to the open lake;
lagoon ice or the development of a ridge further offshore shuts off the necessary wave action against the ridge face, and its growth ceases.
The same wave action that is a major necessity for ridge augmentation has
in it, also, the seeds of ridge destruction. Violent wave action can break up
a ridge and reduce it to floe ice or brash. Less-than-violent wave action,
even when the water is freezing-cold and slush-laden, still will undercut ice
ridges by excavating bottom sand from beneath them; removal of foundation support results in the collapse of ridge sections. Undercutting appears to be
effective only during the active formational period of the icefoot ridges.
Strong, but less than violent, wave action (probably aided by collapse of
undercut ridge parts) will produce local breaches through ice ridges; the removal

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