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

sub-conical elevations with definite sandy color. Over the top of Ridge C in
the left center distance a limited field of brash is visible.
As was the case for Ridge A, and probably Ridge B, Ridge C waxes and wanes
under the same accretive forces and the same destructive factors. This will be
illustrated later.
Formation of the Second Lagoon and the Second Outer Barrier (Ridge D)
During the dead of winter along the eastern shore of Lake Michigan it is
not uncommon for a second frozen lagoon and outer ice barrier to form. This
second outer barrier we have designated as Ridge D. Apparently the second
lagoon and Ridge D form in the same way as the inner lagoon and Ridge C. It is
of interest to note that Ridge D not only can develop into the highest of the
ridges but that it also appears to increase in thickness until it becomes
grounded on the Lake's inner sand bar at a distance of about 500 feet from shore.
Also in the dead of winter extensive fields of brash may move into an area
and temporarily solidify on the lakeward side of Ridge D. However, these fields
of ice soon break up and move away. On 2 February 1971 the tocal ice field off
the Cook Plant site reached to 10.5 miles offshore. By the end of the day the
ice field had broken up and the ice coverage was reduced to the area shoreward
of Ridge D. This is discussed and illustrated in the full report.
The condition of shore structure on 24 February 1971 is shown in Figure 13(74).
In this figure Ridges A, B, the inner lagoon, Ridge C, the outer lagoon, Ridge D,
and a still outer field of brash are all visible, with the Cook Plant in the
background. We have only aerial photographic evidence as to the nature of the
fields of brash ice that form temporarily outside Ridge D. Evidently they are
not too solid, for they vanish quickly. We do, however, have solid evidence as
to the nature of the second ice lagoon and of the second outer ice barrier
(Ridge D).
Figure 14(77) presents an overview of the conditions of the shore ice

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