Riverbed under garden, what does this mean?

Hi all,

I have been told theres a riverbed under the garden, Im just wondering what this means ie disavantages/advantages .... I am renting so its not a big deal for me but just curious in case I at some point buy the property?

 

We on a job in Henley on Thames on an old river bed and they are grouting the ground with volcanic Ash to stabilise as its all shingle deep down

 

Riverbed may mean silt, which is not loadbearing, building a house would mean piling.

I think it all depends on the geology.

 

if there is an active river nearby, i would be worried about the flood risk.