Is it natural, man made or natural and improved by man. If not completely natural how much is due to man & when was it done?
None of the web sites 1've checked or books that i have seem to say anything about its origins.

For us dummys who don't live in Africa and don't know what a Fayoum is, please explain a bit further.

The fsyum (490 sqare miles) is often described as an oasis but it is not. It is fed by a channel from the Nile called the Bahr Yussef.
I have heard someone claim it is man made.According to the name it was made by Joseph (Yussef) as part of the plan to deal with the 7 lean years.

Is it Fayoum or fsyum and what is the significance of this 'oasis'? I guess that we need to know why you are asking and hopefully you can give us some historical background for research. It may very well have a different name. It may not have any significance at all, being a sometime oasis among other oases.

Sorry it is fayum (I have also seen it spelt fayoum).
It is a major part of the cultivatable land of Egypt and contains some major ancient monuments including what is left of the 'labrynth' a building which some ancient writers thought was a greater wonder than the giza pyramids.
My interest is just general egptology - I have 2 quizes in preparation on ancient egypt (neither including questions on the fayum).
As it is fed by the nile it is not a true oasis.

I've found this: http://www.egyptvoyager.com/oases_fayum.htm

If you have done an internet search, you probably already found this site, but it's the best I can do. Good luck.