Diamicton (also diamict), in geology, is mixed content sediment. Large sedimentary grains of gravel size and larger (>= 2 mm) are set in a matrix of fine grains.
The term diamicton is not generic to one, although a common origin for diamicton is the underside of glacial activity. Sediment deposited by glaciers in moraines is characteristically very poorly sorted, showing great lateral and vertical variations in thickness, composition and texture. Once a glacial origin for a diamicton has been determined, it can be called drift or till. Other common sources of diamicton formation are both terrestrial and submarine slope processes, such as solifluction, landslides, debris flows or turbiditic olistostromes.
Lithified diamicton is referred to as diamictite.