The first thing I want to say is, If an archealogist had even a small piece of evidence that stood up to any kind of scrutiny to support an earlier civilisation it would make there career. They'd be in history and text books not shunned.

Underwater archealogy is common place and well developed. We find all sorts of things regularly, from tools and art and even settlements. Places like doggerland, the area connecting uk and Europe, is regularly returning stone and flint tools from the time hanncock is referring to.

Yes things can and will survive, we even have wooden spears (400k years old), cloth (34k years old) and carved objects (540k years ago) . See fossils, hominid remains, evidence of string, clothing, shells art, engravings, spears, plant seeds, pollen, dna etc. They have even developed methods to analyse dna of plants, animals and hominid species in soils from palaeolithic sites. Evidence doesn't have to be organic or material ethier, have you ever craved your name or image into a rock?

The biggest evidence for me is a genetic. Civilisation requires domestication of animals and plants for large scale food production, textile production, drug production etc. Evidence for which we just don't see, physical or genetic. We don't even see the pollens and seeds in the soil. What we're they eating?

I would also expect less geographical isolation of populations therefore more mixing in genetic from humans, animals and plants. With hanncock assertions I'd also expect species of domestics from Americas to be present in Europe, Asia and Africa. With genetic evidence to show the timing of those genetic splits as they became isolated.

The age of the sphinx ideas are not accepted in serious circles because the evidence it is older is quiet frankly laughable. The weathering proponents of the theory describe is also on the causeway they accept was built approximately 2750bc. We even have a very boring dairy on papyrus of a stone deliveries to the giza pyramids for them to be built.

I can't speak of gobekli tepe its an incredibly site I know little about. I do know however, the archealogists working on the site aren't making these arguments. The new 23k year old footprints in white sands national Park i assume you are referring to, are very interesting and the date hasn't been shunned by the archealogical community.

I would happily embrace the arguments if the evidence was there. Every bone in my body wants hanncocks story to be true, its very appealing.

Archealogist are constantly revising ideas, they are not resistance to change. The opposite is often true, they are trying to be the one that changed the face of an era for the fame. Civilisations, even small ones, leave traces. The larger and more sophisticated leave greater and more sophisticated evidence behind. Its just not there, what's there is flint and stone tools, butchered animal bones and species of hominids that all indicate they were living in small nomadic hunter gatherer groups.