There have been many civilizations on Earth, maybe not many were industrial (ancient Egypt was clearly semi-industrial so far as lithic tooling is concerned.)
We haven't looked deep enough very much. Many of the 10-25,000 year sites are buried dozens of feet underground. If there are any previous ruins, they're probably a hundred-or-more feet down. Seaside ruins from 10k+ years ago are now under 400 feet of water and 10k+ years of sediment. We've just started to notice evidence of major changes only 13k years back ... with more on the way.
Over 100,000 years, water has scoured (and deeply buried) much of the surface. Consider the number of glaciations in the past 2M years ... each one of which has scoured the surface in northern regions repeatedly. Much farther back than that, and most geo- and bio-records are erased.
The planet's dynamics would have scrubbed almost anything before 10 million years ago. There've been 400 of those; 5 major extinctions left some traces. The scale of upheavals has been massive. How long ago did the Andes arise? It was first noticed in the 1700s that Whole sections of the Earth's surface have gone missing. https://en.wikipedia.org/wiki/Hutton%27s_Unconformity
ok... i get your point, but the major counterpoint:
as earth / plate tectonic move around, underneath earth is constantly surfaced... from dinosaur fragments, to Cambrian era mollusks found in top of mountains (due to earth's crust movement).
If there was a previous 'intelligent' civilization previous to us, they would have altered their environment to be detectable to us even today.
OK then let's find it. We're not really looking. Maybe it is indeed detectable, and maybe it will be hard. Maybe it's already staring us in the face, and our ideas about it are -wrong-.
We -believed- the Clovis story. Until some people -looked harder-. Plate tectonics ... laughed at. Until some people -looked harder-. Absence of evidence is not evidence of absence.
Exactly. Mullusks. Think of them like ants. Almost exclusively small dinosaurs. Things that would have been everywhere, including many places civilization would never choose to go. They are things that would be much more widespread than gameboys (just giving an example).
We haven't looked deep enough very much. Many of the 10-25,000 year sites are buried dozens of feet underground. If there are any previous ruins, they're probably a hundred-or-more feet down. Seaside ruins from 10k+ years ago are now under 400 feet of water and 10k+ years of sediment. We've just started to notice evidence of major changes only 13k years back ... with more on the way.
Over 100,000 years, water has scoured (and deeply buried) much of the surface. Consider the number of glaciations in the past 2M years ... each one of which has scoured the surface in northern regions repeatedly. Much farther back than that, and most geo- and bio-records are erased.
The planet's dynamics would have scrubbed almost anything before 10 million years ago. There've been 400 of those; 5 major extinctions left some traces. The scale of upheavals has been massive. How long ago did the Andes arise? It was first noticed in the 1700s that Whole sections of the Earth's surface have gone missing. https://en.wikipedia.org/wiki/Hutton%27s_Unconformity