Complex sentence: After the 1985 DC Comics event "Crisis on Infinite Earths" merged the various parallel worlds DC had established over the decades into a single universe, the older, "Golden Age" versions of DC's mainstream heroes were largely eliminated from continuity.
Split into simpler sentences: After the 1985 DC Comics event "Crisis on Infinite Earths" merged the various parallel worlds DC had established over the decades into a single universe. The older, "Golden Age" versions of DC's mainstream heroes were largely eliminated from continuity.