The Mellotron Group

No doubt this has been asked before... does anyone know for sure what sounds were used for the first minute or so? There's the initial 4 stabs, which may or may not be the same as that for the next minute. Is it just distorted strings? Are there horns and/or choir in there as well. It's a very unique sound which I'm sure is partly a result of processing or being over-driven, but I'm really curious as to what actual mellotron sounds it originates from.

-Jamie