But if they were created in 7600 B.C. They should be visible in Chrono Trigger, unless when they were created the dimensions split and the timeline without them was in Chrono Trigger. But that would not explain Chrono Cross being in the same world as CT.
They could not be created in 7600 B.C. and also created when you get done with CT. Because in CT, if you go back and change an event in time (ex. Fiona's forest), when you travel into the future, it is as if they were always there. And when you give the Jerky to the lady, she teaches her ancestors to be nice. So the once asshole mayor becomes nice and gives you the sun stone. This shows that when something is changed in the past, the direct future is altered.
So...if the islands were created in 7600 B.C. they should be visible in CT. This is what I'm getting out of it anyway. I was thinking this because the only way for them not to be seen for the reason of them not being made until after CT, would be that the timeline of the future and the timeline of the present run parallel to each other, meaning that if a certain event and all of the things resulting in it (Time Crash, and Chronopolis being thrown into the past and creating the El Nido islands) happens in a timeline greater than another (events in Chrono Trigger) then Event B is not altered, even if Event A is thrown into Event B's past, if you get what I'm saying.
And this simply cannot be the case because of the above examples resulting in the changing of the future. If you travel back to 12000 B.C, from 2400 A.D. in the Epoch and place the Sun Stone in the Sun Keep, it will be there in 1000 A.D. It won't simply disappear because the event of it being taken back happened after the point it time were it initially wasn't there.
And another thing. Saying the CT and CC are the same world, which they are supposed to be, just 20 years later, then why would it be there in 1020 AD and not 1000 AD. And how would settlers begin to colonize El Nido in 920 AD and it not be there in CT.
I was under the impression that FATE had something to do with keeping El Nido away in Chrono Trigger because it was FATE's paradise to let the time and events happen according to her plan up till the Time Crash. And in order to do this, she needed to close off the people of El Nido from the outside world.
Edit: Damn the more I read my stuff the more I sound like I make no sense. But if you need me to explain just ask.