Glaciers act as conveyor belts of debris. A moraine is an accumulation of rock and sediment deposited directly by glacial ice. End moraines mark former ice margins; lateral moraines form along valley sides; medial moraines appear where tributary glaciers join.

Till in moraines is typically unsorted and may contain boulders of many sizes. The shape and position of moraines record the extent and flow patterns of past glaciers. Recessional moraines indicate pauses during overall retreat.

Moraines create natural dams that impound lakes and provide ridges that influence drainage and land use. In formerly glaciated regions they are among the most visible reminders of ice-age conditions. Mapping moraine sequences helps reconstruct the chronology of glacial advances and retreats.

• Glacial deposit of unsorted rock and sediment
• Marks ice margins or flow paths
• Includes end, lateral, and medial types
• Records past glacier extent and behavior