Formation of Eskers Flashcards
What is an esker?
An esker is a long, sinuous ridge composed of stratified sand and gravel laid down by glacial meltwater. Material is deposited in sub-glacial tunnels as the supply of meltwater decreases at the end of the glacial period.
What may carry huge amounts of debris under pressure in confined tunnels at the base of the glacier?
Material is deposited in sub-glacial tunnels as the supply of meltwater decreases at the end of the glacial period. Sub-glacial streams may carry huge amounts of debris under pressure in confined tunnels at the base of the glacier.
When does deposition occur in the formation of an esker, according to some scientists?
Some scientists argue that deposition occurs when the pressure is released and meltwater emerges at the glacier snout.
What happens to the point of deposition as the glacier snout retreats?
As the glacier snout retreats, the point of deposition will gradually move backwards.
Why do some eskers show significant variations in height and width, appearing beaded?
This may explain why some eskers are beaded - the ridge showing significant variations in height and width - with the beads of greater size representing periods when the rate of retreat slowed or halted.
What is an alternative explanation for the beaded appearance of some eskers?
However, others argue that the beads are simply the result of the greater load carried by summer meltwater (Figure 2.24).
Where is the Trim esker located?
The Trim esker is near Dublin.
What are the characteristics of the Trim esker?
The Trim esker is 14.5 km long and between 4 and 15 m high.
How many eskers are there in the Trim area near Dublin?
The Trim esker near Dublin is one of a group of twelve in the area.
