1. “In-A-Gadda-Da-Vida” Iron Butterfly June 14, 1968.
2. “In Held Twas In I” Procol Harum September 1968
3. “Facelift,” “Slightly All The Time,” “Moon in June,” “Out-bloody-rageous,” all from THIRD by Soft Machine, June 6 1970.
4. “Atom Heart Mother” Pink Floyd October 2, 1970
5. “Blows Against the Empire” (side two from album by the same name) Paul Kantner/Jefferson Starship November 1, 1970
6. “Winter’s Dream” November ???, 1970, from Entrance by Edgar Winter
7. “Amboss,” “Traummaschine” Ash Ra Tempel June 1971
8. “Tarkus” ELP June 14, 1971.
9. “A Plague of Lighthouse Keepers” Van Der Graaf Generator October 1971
10. “Echoes” Pink Floyd October 31, 1971.
11. “Schwingungen” Ash Ra Tempel, ??? 1972
12. “Thick as a Brick part 1” & “Thick as a Brick part 2” Jethro Tull, March 3, 1972.
13. “Spring,” “Summer,” “Fall,” “Winter,” all from Sonic Seasonings Wendy Carlos ??? 1972
14. “Close to the Edge” Yes September 13, 1972
15. “Supper’s Ready” Genesis October 6, 1972
16. “Space,” “Time,” both from Seven Up by Ash Ra Tempel ??? 1973
17. “Tubular Bells” Mike Oldfield May 25, 1973
18. “A Passion Play pt 1,” “A Passion Play pt 2,” Jethro Tull, July 13, 1973
29. “Remember the Future part 1,” “Remember the Future part 2.” Nektar November 23, 1973
20. “Revealing Science of God,” “The Remembering,” “The Ancient,” “Ritual,” TALES FROM TOPOGRAPHIC OCEANS Yes December 7???, 1973
POST TOPOGRAPHIC EPICS
21. “The Gates of Delirium” by Yes 1974
22. Solar Musick Suite Steve Hillage April 1975
Church of the Educated Guess 
Good post!
Don’t overlook the influence of jazz epics, of course, like Carla Bley’s Escalator over the Hill, or John Coltrane’s Love Supreme. (And though not at the level of most of the other references you mention, it is worth remembering Days of Future Past.
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I’m skeptical about using jazz epics, because they can often be just rambling improvs. Miles Davis did an entire double album of side-long epics. I like two of Eberhard Weber’s epics, “No Motion Picture” and “Fluid Rustle.” The prog versions are much more arranged. I don’t include the Moodies album because it’s just a concept album, with songs strung together. I love it, but I was looking at long form 15+ minutes songs. That’s what Yes did on Tales.
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