@BearGrounds, this is why your threads are so shallow. You quoted something which isn't a fact and are expressing is as though it is a fact. Who is the author behind the quote "which and be viewed only from space" ? It's not the scientist so who said it how accurate are they?
Crop circles are human made and that's just what it is. Dave and Dave made millions of people look like absolute morons when they're talking about them being made by alien creatures. It's fun to think about, sure, but it's not a realistic explanation when there's definitive evidence showing they can easily be reproduced by people with a board and a string.
As for the geoglyphs I WANT to believe they can only be appreciated from the air, but as I suggested hills and mountains also provide a birds eye view. We have no definitive answer as to why the ancients built these things in the manner which they did, but I just don't believe that trying to signal alien aircraft is the most plausible reason. Again, I was seriously fascinated by the stuff in Peru and it's such a fun theory to take in, but there's just no real credibility behind it at all. 99.9% supposition with .1% of misinterpretation.