Pre-Columbian influence from across the Atlantic would be like adding a pinch of Salt to a 10 gallon pot of stew. The reason Native culture did not rise to the advancement of other parts of the world is no horses. Once horses arrived you see a dynamic change in many Native cultures and redistribution of territories, some groups gaining larger areas forcing others to move.
If horses had been here long before the Europeans arrived thing may have gone different, who knows, possibly Native Americans discovering Europe.
That is why I made the remark about horse remains with the car battery lead. If an advanced culture moved here they would have had horses and other domestic animals. There is no such evidence of this in pre-columbian time.
Lack of knowledge is what holds back man's cultural achievements.
Horses are a tool, but the New World had no indigenous horses since the end of the Pleistocene Age - the animals being reintroduced with the Spanish Conquest. However, despite a lack of horses, it can be argued that significent human cultural advancement did indeed occur in a number of New World venues. The Spanish's shock at Tenochtitlan's sophistication, our own respect for the Mayan's cosmology and the world's wonderment of a dozen other stunning archeological sites in Central/South America prove that point. None of these obviously knowledgeable cultures had horses.
They did have plenty of knowledge though, and it seems likely that knowledge wasn't home grown, but was given to them by persons whom we can't yet identify conclusively. Based on a boatload of cultural, symbology and architectural similarities, and New World traditions, the New World cultural knowledge came from points east. The North American story isn't as clear, although the Mound Builders in the South and Midwest left lots of intriguing artifacts that were frequently plowed up by farmers, then dismissed by experts as frauds. Here in the Southwest, most of the ruins are basicly crude. Chaco is an exception - I tend to buy the idea that it was a temporary stop for migrating Aztecs who may have begun their journey at Cahokia, a site with similarities to Central American sites.
That said, what about the questions oldpueblo raised? I have a lot of ideas about the subject, but these are my quick-and-dirty opinions:
1) I think there are secret hidden sites in the Southwest. Any 'information' released about them, in any manner (introduction of fake artifacts, disposition of genuine artifacts, discovery of maps, testimony of individuals, etc.) is done to obfuscate the truth and misdirect the curious. Many, many of the 'treasure clues' and gold legends surfaced in the 1930's.
2) Nobody outside the tightly controlled Organization, which owns and controls the sites, will ever be given knowledge of them.
3) It's all about diversion - the clues, the carvings, the legends, all of it. The Organization allows the curious to run in circles away from their sites. Waltz may possibly have been an Organization man. IMO, trying to understand the 'Calalus/Oz' stuff posted on these threads is a waste of your time.
These are my opinions only and can't be proven.