Landforms off glacial deposition Flashcards
What is a moraine
Rock material carried by a valley glacier and deposited to form a range of landforms
Name landforms of glacial erosion x8
Ice contact features:
Lateral moraine
Medial moraine
Terminal moraine
Recessional moraine
Drumlins
Lowland depositional features
Till plains
Lodgement till
Ablation till
Description/formation of lateral moraine
A ridge if till deposited along valley sides
Debris from freeze thaw of valley sides fall onto glacier. Then transported and deposited at the edge of a glacier when it melts
Description/formation medial moraine
A ridge of till deposited in middle of The Valley (parallel to valley sides)
At the confluence of two tributaries glaciers the lateral moraine joins to form medial moraine and deposited during ice melt
Description/formation terminal moraine
High ridge of till extending across a valley at right angles to The Valley side, marking the the limit of glacial advance
Material picked up and deposited at snout of glacier building up a moraine
Description/formation recessional moraine
A lower ridge of till found at end of glacier due to retreat of glacier and material is deposited
Caused by retreat of glacier or when glacier remains stationary for long time causing material to build up
Description/formation drumlins
Smooth elongated mounds of till parallel to the direction of ice movement, with a steep stoss and gentle lee. Often found in clusters
Formed by deposition when glacier ice becomes overloaded with debris when exiting an upland area
Description/formation till plains
Large mostly flat plain of till in lowland area (also called ground moraine)
Sheet of ice retreats large amount of material deposited over large area due to melting
Description/formation lodgement till
Deposits of angular rock fragments (clasts) in a fine matrix and unstratified (not layered) unsorted (mixture of clasts)
Till deposited by active moving ice forming drumlins
Description/formation ablation till
Deposits of angular rock fragments (clasts) in a fine matrix, unstratified (not layered) unsorted (mixture of clast sizes) and erractics (mixed geology)
Till deposited by melting ice from stationary/retreating glaciers forming terminal and recessional moraines
What are clasts
Clasts are deposits of angular rock fragments
How can we identify relict glacial landscapes
Studying the landscape
-distribution of moraines
-mapping erosional and deposition landforms (glacial troughs drumlins)
What is the fieldwork technique for studying relict glaciers
Till fabric analysis
-rose diagrams
It looks to work out the direction of ice movement from the position of clasts
