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A good example of Ice Powerl This photo was taken on Otter Tail take, Otter 'Ir'all County on February 4, lg87. DOWns Bruce Winterleldt (6ft.-6ln.) Is standing near this ice heave for perspec- five. (Photo #2) Then, as Murphy's Law would dictate, the worst that can happen happens. The crac'ks don't stay open to allow room for the next expansion event of the ice sheet! Instead, the water in the crac 'ks freezes, forming new ice and stealing the space that othcrv,4se would have served nicely to ac- commodate thermal expansion. The ice sheet couldn't care less. When its temperature rises again, its thermal expansion forces get into gear exerting its relentless force again upon the shoreline. As each successive expanslon/contract~on event occurs, the ice sheet creeps further, scraping, gouging and pushing as it goes. Some people call this process "ice-jacking" because of the ratchetlng effect that each subsequent and cumulative push exerts upon the shore. Regardless of the name given to it, the effects of the power of ice are apparent and some- times painfully real, as can be seen in the accompanying photos recently taken in northwestern Minnesota. Its vic- tens are the boathouses, cabins, docks, sidewalks and retaining walls which were installed along the shoreline without regard to this phenomenon! - Ice Power! As fearsome as it can be, it does have its ups and downs and can be dealt with intelligently. First, and fortunately, there are good years and bad years for damag- hag ice action. During years of early snow fails and deep snow cover, the snow helps insulate the lake ice. This keeps its temperature more constant and thus minimizes The foundation of this cabin on Big Cormorant Lake suffered damage when Ice lacking Jammed an unattached deck into the foundation block.(Photo T. aken on Lake I.ida, Otter Tall County on January 8, 1987, this photo shows an example of 'ice jacking' where the expansion force was relieved et a weak spot In the Ice a safe distance from shore. This saved the adjacent landowners lots of grief, come eprlng.(Photo #3) "ratchcting". But in other years when snow cover is light or absent (like this past winter) and temperature extremes are great, look out! Ice power will then unleash its worst fury and maximum total expansion will occur. There are basically four ways to deal with ice forces in shoreland areas: 1) do nothing at all 2) do nothing, then restore damage 3) attack its strength 4) attack its weakness Any of the four approaches may be appropriate for a given situation. Taken separately, the fn'st approach: "do nothing at ail", is obviously the cheapest. It could best be utilized in undeveloped shoreland areas. Surprisingly, this can be one of the most effective methods because, ironically, the lake itself builds its own protection against it- self. For example, a small earth pressure ridge is pushed up one year followed by additional pushes in ensuing years.This not only enlarges the pressure ridge, but often fortifies it by jamming roc~ into it. Roots of trees, brush and other vege- tation then bind together the soll and'rock.After a period of time you will have a natural retaining wall that will adequately protect personal property on its landward side. The next time you're on Minnesota lakes, look for these ridges. Thefre there! Continued on page3 : ,...~,,:.~,- . . .-..... . ..... · ~ .~.. :.:?.,, .:.,._', .~. . .... ,. An aeration system along this shoreline of Big Cormorant Lak~ was used as a preventive measure against ice jacking. Aerafior can be an effective tool but requires a DNR, Section of Fisherie., permit and can be a liability for its owner. (Photo #5)