Why do freezing and thawing cause rocks to break?
370818
water can seep through cracks in rocks and remain there. when water freezes, it expands because the type of bonding changes. in ice, each oxygen atom is surrounded by four hydrogen atoms (two through covalent bonds and two through hydrogen bonding), producing a tetrahedral structure. this gives ice a more open structure compared to water. \n\nso, the water freezes and expands, creating pressure within the rock which causes it to split or break.
240715
The answer to this problem lies in colligative properties.  The salt ice solution will have a lower freezing point because by adding the salt, the solution is going through freezing point depression, which means that the solute is spreading apart the molecules of the solvent, thus requiring a lower temperature to freeze.
1093172
Due to the weight of the glacier the ice at the bottom melts.The water is under great pressure and is forced through cracks in the ice eventually forming tunnels.Bacteria,spores and pollen have been found in glacial ice.
13071
Rock salt decreases the freezing point of water which causes melting.
319184
if the cold thing is cold and crystaline, like pyrex or ice, the object cracks because of rapid localised expansion.\n\nIf it is really really cold, the water will crystalise.\n\nIf cold water hits something hot it forms little drops with a protectice steam jacket and they bounce around for ages, a cool experiment for home on a hot frying pan. (only uses drops of water though)
8528
All freezing (or rather: crystallisation) occurs on surfaces or crystal seeds. Water freezes "from the bottom" because liquid water closer to freezing has a greater density than solid water (aka ice), so the frozen crystals float up. In cases where the solid has  a greater density than the liquid (probably the majority of cases), the solid will sink down.
47243
Mechanical weathering is the breaking down of rock or soil by mechanical means.  This may include frost heave, force of roots, ice forming in cracks and the force of wind driving sand particles like a sand blast.  See the sources for illustrations.
36498
it has to do with moisture and heat.  If moisture gets into the grain of the wood, then it will swell the wood.  now when the wood gets cool again, it shrinks and then when it's warmer it expands, so it eventually cracks, you need to have a good seal on the wood so moisture won't get in there.\n\nan extra tidbit about hot and cold cracking-  did you know that on mountains where water runs in the summer and freezes in winter, the moisture in the rocks can make them split because the ice expands and spreads the molecules in the rocks.
762290
Water...\n\n* Liquid water, eg in rivers and coasts (in the sea this is largely caused by the gravitational effect of the moon);\n* Liquid water is a major cause of landslides - soil becomes over-saturated and therefore loses its adhesion to the soil or rock beneath;\n* The action of freeze-thaw where liquid water seeps into cracks, expands when it freezes thereby widening the crack and ultimately splitting rocks apart;\n* Frozen water in the form of glaciers grinding away at mountains;\n\nOther causes of erosion include:-\n* the wind, especially when it blows sand particles with it which erode rocks;\n* the Sun which alternatively heats and cools rocks so that they split in much they same way as freeze-thaw (especially in desert areas);\n* humans - we contribute to many of the above processes by our own actions, eg deforestation prevents the soil from holding as much water so landslides become more likely; over-farming creates deserts which are subject to wind and sun; coastal "management" often results in more rapid erosion of some areas of coastline
1171684
Erosion breaks up igneous and metamorphic rocks, and the particles build up to create sedimentary rocks.  \n\nHope this is helpful.
1077388
Mechanical factors break things down physically - ie. ice wedges cracking rocks.\nChemical factors break things down through chemical reactions - ie. acidic water reacts with limestone to decompose the chemical structure of the stone\nBiological factors (ie. animals and plants) break things down either physically (animals moving around under the surface, roots wedging into cracks) or chemically (animal 'by-products' cause chemical reactions)
218041
It is quite true that soil temperatures where the living parts of the plants are during winter are not as cold as the surface temperature. That is the first fact. The second thing that comes into play is that plants produce chemicals that depress the freezing point of water and prevent ice crystals from forming and rupturing cell walls. The next factor is that many plants forms seeds or spores that are biologically inactive when conditions are not suitable for growth. This is sort of a suspended animation. It is also important to recall that plants even as large as trees have only a very small proportion of actual "living material." In a tree in winter, the cambium and rootas are "alive" The cambium goes inactive and reactivates when spring comes and the roots remain fairly dormant through winter until warming weather stimulates the cambium back to life and the roots then beginning sending sap up the tree. The question is complex as plants vary from one celled organisms to trees.
851419
the gases build up that pushes the molten up, if there is snow causes hazardous and gaseous mud slide down the mountain.  Causes some tremors like earthquakes. Hazardous smoke (ash) cloud.  look up mount saint helens in Washington or the volcanoes in hawaii.  plus there are many throughout south america.  Pictures of mt. st. helens are awesome. I went there after it happened in 1980 it was phenomenal!  I felt the tremors up by bellingham. it was cool.
11514
large rocks break into smaller rocks by means or erosion, and by water seeping into cracks and freezing.  Ice may be rarer in deserts, but it is not unknown.  Wind also plays a role in erosion, but much less.  In some cases, rocks might have been formed in other places, and carried to distant places by rivers or glaciers.  Deserts weren't always deserts--a place that is today a desert might have once been a swamp, a prarie, or the bottom of a lake or sea.
284203
Ice lowers the melting point of water, so it causes the ice to turn to liquid water and break up.  If it's *really* cold, this doesn't help.
66544
Salt will lower the freezing point of water. That is why the use in on the roads in winter.
89574
The chemical reaction from adding\nsalt lowers the temperature in which water freezes.\n\nThat is why they throw in onto the roads in areas of winter freezing.