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Lesson Content (Summary of Key Ideas / Concepts) Periglacial Processes and Landforms (3) Landforms due to Freezing in the Ground (Cryoturbation / Segregated Ice / Ground Cracking) continued.... 3. ICE WEDGE POLYGONS (processes involved, ground cracking, ground ice and frost heave) 
4. STONE-SORTED POLYGONS (processes involved, frost heave - some ground ice, but less preciptiation so no significant ice wedges formed) 
 REMEMBER - do not confuse Ice Wedge and Stone Sorted Polygons - they are different and form due to different processes: Comparing Ice Wedge Polygons and Stone Sorted Polygons Feature | Size | Characteristics | Processes Involved | Ice Wedge Polygons | Large in size (20-30m in diameter | Low in the centre / raised rims (often small ponds in the centre) | Ground Contraction and Ground Ice Processes | Stone Sorted Polygons | Small in size (1-2 m in diameter) | Raised in the centre (fine sediments) - surrounded by coarser stones. | Frost Heave Processes |
Lesson Resources (Handouts and Extra Links) Ice Wedge Polygons and Pingos (Arctic National Wildlife Refuge) - includes an animation Formation of Ice wedges and ice wedge polygons (Arctic National Wildlife Refuge) - excellent site |
