Glacial Troughs Flashcards
How are glaciers formed?
The glacier straightens, widens and deepens the river valley, changing it from V shaped to U shaped.
Where does the power come from to erode the valley?
The action of the ice, combined with huge amounts of meltwater and subglacial debris, has a far greater erosive power than that of water.
When are glacial troughs formed?
When glaciers flow down pre-existing river valleys as they move from upland areas.
What are the major features of glacial troughs?
> Straight with a wide base and steep sides
Stepped long profile- alternating steps and rock basins
Trough end- end abruptly at their heads with a steep wall
Rock basins filled with ribbon lakes
Over-deepening below the present sea level
Hanging valleys
Truncated spurs
Roche moutonnees
Shallow lakes
How are fjords formed?
When sea levels rose after the ice ages and submerged the lower parts of glacial valleys eg. coasts of Norway
