Lis, soil not freezing in a cold zone is a fascinating concept to me! Here it varies a lot from one spot on the property to another, depending on soil moisture and exposure to sunlight etc, but most of the soil surface at least is frozen solid long before there is lasting snowcover, and, in shady spots, even while daytime temps are well above freezing.. spots with dry soil in the sun do not freeze until much later.. In spring, when snow is melting, there are pools, puddles and flooded fields everywhere, since the ground is still frozen and no water can soak in, again, in shady spots, and depending on weather, that soil can remain frozen for some time after the snow is gone.. Native evergreen plants such as Pyrola can suffer some leaf damage in years when early melts expose the leaves in February, when ground is frozen and they have no access to moisture for many weeks yet..
I've never tried to dig below the rock hard surface to see how far down it goes, I do know water/sewage pipes are kept well below the surface to avoid freezing, but have never been involved in the construction etc to know the details... I should see if my mom knows more, having lived most of her life out here.... Another interesting subject I have not thought about much :) Cohan On Sun, Apr 17, 2011 at 6:24 AM, Lis Allison <[email protected]> wrote: > On April 16, 2011, cohan fulford wrote: > > > > I'm no expert on frost lines, Cohan, but I do know that the official frost > lines in Canada have more to do with the depth footings need to be, or > road beds need to be and so on, than with the actual depth to which soil > freezes in a typical winter. Here in Ontario, footings have to be deeper > than (I think) 4 feet, but the ground never freezes that deep. Even in a > very cold winter (-30C) with no snow cover, the ground only freezes about > 1 foot down. If the extreme cold lasts longer, than it freezes deeper. In > practice, however, we almost always have good snow cover, and most winters > the soil doesn't freeze at all. > > Tundra happens when the temps stay low enough long enough that the frost > never completely leaves the ground, thus causing the next winter to add to > the existing frozen soil. If you think of a block of ice, say one cubic > foot, surrounded by air or warmish soil, it takes a certain amount of cold > to freeze it solid. If you take the same cubic foot of water and put it on > top of a solid block of ice, it will be easier (quicker) to freeze. Tundra > soil never completely thaws out, only the top thaws, and so the frost line > will be very deep indeed. > > Lis > > Lis > -- > Lis Allison > Pine Ridge Studio > www.garden-on-the-ridge.blogspot.com > _______________________________________________ > Alpine-l mailing list > [email protected] > http://mailman.science.uu.nl/mailman/listinfo/alpine-l > -- West Central Alberta, Canada, Zone 2-3 record temps from 10-20 miles away: min -45C/-49F;max 34C/93F http://picasaweb.google.com/cactuscactus
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