This shows the buried valley
of a large river in the floodplain. At some time in the past,
the river cut a trench in the
underlying silt and deposited
gravel.
The river changed its course and deposited further alluvium on top of the old channel.
This old river channel, filled with gravel, has a major effect
on the groundwater flow along
the valley and the channel
affects the groundwater level in
the alluvium.







