depositional landforms

• what is a medial moraine? (depostional)

  A medial moraine is a ridge of moraine down the MIDDLE of a valley floor
• how is a medial moraine formed?

  When two valley glaciers converge, two lateral moraines combine to form a medial moraine. Material is carried and deposited when melting occurs. Parallel to ice flow
• what is a lateral moraine? (depositional)


  A ridge of moraine along the edge of the valley floor
• How is a lateral moraine formed?

  Exposed rock on the valley side is weathered and fragments fall down the edge of the glacier. This is then carried along the valley and deposited when the ice melts. Parallel to ice flow

  Only form in the ablation zone of a glacier
• what is a recessional moraine? (depositional)

  A series of ridges running across the valley behind the terminal moraine
• how is a recessional moraine formed?

  Each recessional moraine ( and there may be many) represents and stand-still during a ice retreat. They are good indicators of the cycle of advance and retreat that many glaciers experience. Transverse to ice flow
• what is a terminal moraine? depositional

  a ridge of moraine extending across the furthest point the glacier reached
• How is terminal moraine formed?

  Advancing ice carries moraine forward and deposits it tab the point of maximum advance when it retreats. The up-valley (ice contact) side is generally steeper than the other side as the advancing ice rose over the debris. Transverse ice flow
• what is a drumlin? (depositional)

  Smooth, elongated mounds of till with a long axis parallel to the direction of ice movement and with a steep stoss and gentle lee; often found in large numbers in an area called drumlin swarms and forming ' baskets of eggs' topography
• How is a drumlin formed?

  They are formed by deposition when glacier ice becomes overloaded with debris when exiting an upland area. The deposits are streamlined and shaped by the moving ice . They are valuable indicators of the direction and velocity of past ice movement
• What is an erratic? (depositional)

  Individual pieces of rock varying in size from small pebbles to large boulders, composed of a different geology to the area in which they are found
• how is an erratic formed?

  Rock eroded most likely by plucking, or added to the supraglacial debris by wreathing and rockfall, in an area of one geology and then transported by a glacier, often long distances, before being deposited during melting in an area of differing geology.
• what are till sheets? (depositional)

  Large thick mass es of large unstratified till forming extensive and relatively flat surfaces
• How are till sheets formed?

  Larger amounts of till are deposited at the end of a period of ice sheet advance during melting and retreat
• what is lodgement till? (depostional)

  Deposits of angular rock fragments in a fine matrix, unstratified, unsorted and containing erratics
• How is lodgement till formed?

  Till is deposited by actively moving ice, forming landforms such as drumlins. It is lodged or pressed into the valley floor beneath the glacier
• What is ablation till? (depositional)

  Deposits of angular rock fragments in a fine matrix, unstratified, unsorted and containing erratics
• how is ablation till formed

  Till is deposited by MELTING ice from stationary or retreating glaciers forming landforms such as terminal and recessional moraines