Russ - cracks will occur in the ice layer due to the ice expanding as it thickens during freezing. Freezing and expanding ice has to relieve the pressure as more ice is forming, thus the term "stress cracks". On very cold nights when ice is forming rapidly, my pond produces lots of cracking noises some of them will shake the house. It almost sounds like thunder.
Snow even light snow does have a fair amount of weight to it especially if it is deep snow. Wet snow is obviously even heavier.
