Monster Buck skull

[Bill Turner]

I suspect that that deer has been under water for a while. Probably died in the pond or close enough to be covered by the run off from the  heavy rains in your area last spring and summer.
Doesn't matter. What matters is that it is a great find. Congratulations.  

[Hoytman]

It looks to me like a buck on the downhill slide. I wonder if it just died from old age.

[Wudstix]

Cool beans.  That is an awesome deer.  Let others I'm glad the critters didn't get it.