2a.Landforms - Depositional

Question 1

Depositional landforms

Answer 1

• Moraines (terminal, lateral, recessional)
• Erratics
• Drumlins
• Till sheets

Question 2

Moraines

Answer 2

Terminal Moraine

• Ridge of till extending across glacial trough (crescent shaped)
• Mark the position of max ice advance
• No friction with valley sides supports steep valley

Lateral Moraine

• Ridge of till running along edge of valley
• Material accumulates at top
• Material sinks and deposited due to retreating glacier

Recessional Moraine

• Ridges running transversely and parallel to each other
• Found further up the valley

Question 3

Erratics

Answer 3

• Individual piece of rock varying from small pebble to large boulder, deposited
• Composed of diff geology from the area, transported
• Added to debris by weathering / rock fall
• Likely they have been plucked

Question 4

Drumlins

Answer 4

• Mound of glacial debris, streamlined into elongated hill
• Can be 1km length and 100m high
• Pear shaped in direction of ice flow
• Higher end faces ice flow direction
• Formation not fully understood, can be formed by:
• Lodgement of subglacial debris (melting)
• Reshaping of material during re-advance
• Accumulation of material around obstruction
• Thinning of ice, reducing debris load

Question 5

Till sheets

Answer 5

• Large mass of unstratified drift deposited at end of ice sheet advance
• Till varies on nature of rocks
• High clay content = hard deposit due to compaction