Let's think about this idea.
Earth is billions of years old.
Anything that man has made will turn to dust within 1 million years, yes dust, sand gone from its molded existence.
So let's pretend 500 million years ago when the dinosaurs roamed an alien spaceship crashed here. Maybe they survived here for hundreds of years or maybe it was a smoldering wreck with no survivors. Eventually they all died off. Their ship and what structures they built after the next million years would be dust. Not a single trace.
Possible? I think it is possible even if unlikely.
Earth could have evolved a race with superior technology to what we have today millions and millions of years ago. Then it disappeared, turned to dust some how, without leaving a trace.
The oldest things man made on earth today are about 200,000 years old. All those artifacts were found in caves or buried protected from the environment somehow. Even the Sphynx in Egypt stands today because it was buried under sand for long.
Just my thoughts. I do think aliens have been here maybe still are. Maybe they are looking at us wondering how long it would take them to get here.
Nice post. upped and followed.
Why not ? Everything is possible, i think trace would have been let unless time or some events would have erase them.
of course it's possible. I think it is more likely they arrived and disappeared rather than never have arrived.