Ice Wedge
Ice wedge explained in an easy to understand way:
Imagine trying to fit too many clothes into a small suitcase. Just like how the suitcase bulges and eventually might strain at the seams or even break when you zip it up, water that seeps into the cracks of a rock expands when it freezes, creating pressure. In both cases, the extra volume—whether it's clothes or ice—forces the container, be it a suitcase or a rock, to crack under pressure.
Practice Version
Ice Wedge: When water seeps into a rock, then freezes and expands, cracking the rock. Ice wedge. An ice wedge is a crack in the ground that forms when water freezes and expands in cold weather.