Generally, it can be done using carbon dating - when an object such as a standing stone is placed, objects such as seeds and pollen are likely to get into the hole (or, in the case of recumbent stones, be trapped underneath). Likewise, there may be traces of tools made of wood or antler, which can be dated using the same method, and/or possibly offerings such as stone or metallic objects to which an approximate date can be assigned by comparing them to other objects that have been reliably dated.

@Jnei

I am aware of this, except that one must make the assumption that the organic material nearby (or in the cracks) is contemporary to the structure. There are literally hundreds of examples of when such assumptions have turned out to be completely erroneous. This being but one of them.

@Piratefish Organic matter in cracks or nearby, yes; however, a significant amount of organic matter buried in the soil around a stone's base or trapped under it, especially if there is no other similar organic matter that tests as much later, is likely to give an at least reasonably good indication of the date. In this particular example, the site investigation was at an early stage; had it have progressed to the point when excavations were made under the stones it probably wouldn't have been very long before archaeologists began finding artifacts such as seeds and other organic matter that dated to the modern era in places it couldn't have been unless it was already there when the stones were put into place - seeds, pollen and so on are some of the first things we look for during any field study of this type.

@Jnei

I am in finance by education. I obviously still have a lot to learn about archaeology: something in which I have long been interest and fascinated by, but have little formal background or education in.

Thanks for taking a moment to elaborate without being condescending. Wish there were more people like you on the internet.

@Piratefish Your point was perfectly valid, and correct - it is indeed difficult to date sites of this type and we have to make do with circumstantial evidence to get a statistically likely approximation, so it deserved proper explanation.

I know absolutely nothing about finance, so perhaps one day you'll be able to return the favour.

@Jnei

I keep thinking of objects like the sphinx. I have read a lot of very credible things, posited by very credible people, that suggest mainstream thought about its age and origin may be very inaccurate.

I also have seen a lot of evidence that casts serious doubt on the currently accepted origins of Native Americans, and the time when people first arrived in the Americas. It was only fairly recently that the Clovis points discoveries called established history into serious question.

I realize there are differences between dating events and objects, but it adds weight to the critique of how certain things are dated. Too often, we treat dating as a hard science, when it far more closely resembles inductive logic.

@Piratefish There are a few theories which claim the Great Sphinx may be as old as 10,000BCE, but they tend to rely on suppositions rather than evidence and as such are usually regarded as fringe archaeology or pseudoarchaeology - as the old saying goes, "extraordinary claims require extraordinary evidence" and there isn't much evidence for the Sphinx being a great deal older or younger than about 2500BCE. One of the most compelling reasons to believe that date is correct is that it falls into an era when the Old Kingdom was creating a great deal of monumental architecture, especially tombs which can be dated accurately if we know the identity of the person it was built for and when s/he lived. It's not impossible, of course, that the Sphinx had already been there for many thousands of years, but had there have been a culture in Egypt capable of building on such a vast scale 12,000 years ago it would be very strange if the Sphinx was the only trace they left behind. However, in this case, it's difficult to search for actual physical evidence of the Sphinx's age because the Egyptian government are notoriously unwilling to give permission to study it; therefore, most archaeological investigations were carried out in the 1920s and 30s before modern techniques were developed.

I don't know much about the origins of the Native Americans due to it not being an area I've studied (my speciality is Neolithic Europe). I was under the impression, though, that their geographical origins are still believed to be Eastern Asia and that theory is backed up by genetic evidence; but that the time they're believed to have crossed the Beringia land bridge has been adjusted to an earlier date as new evidence has come to light.

@Jnei

I have heard good arguments from geologists who have examined the sphinx and believe it is several thousands of years older than the Egyptian empire. Of, course, I'm neither an archaeologist, nor a geologist. I just listen to both of their arguments and then form my own opinion as to whom I believe is more likely correct.

As for the earliest Americans, I have very recently watched some documentaries that offer exceptionally compelling, scientific evidence of South Pacific islanders being the first to the Americas, via South America, (specifically where modern day Peru and northern Chile are). And much, much earlier than when the current thinking on the topic is.

@Piratefish I would, obviously, have to read those arguments before I came to any conclusion regarding whether or not I felt they were worth considering.

If evidence were ever found to prove the South Pacific Islanders made it to the Americas, it wouldn't really be a big surprise - after all, they were remarkably adept at navigation and managed to colonise an enormous expanse of the planet's surface.

@Jnei

Have you ever sought out the geological evidence? I first learned about the hypothesis a few years ago from watching a PBS special. It intrigued me enough to look more into it. Two geologists (Robert Schoch and Colin Reader) initially advanced the idea after studying the sphinx in the 1990's and 2000's, and now geologists from around the world seem to be agreeing that the evidence is pretty strong that the sphinx, and its enclosure walls, could be up to 9,000 years old.

I don't think the idea of fairly sophisticated civilizations predating Mesopotamia is that far fetched anymore. The idea that some may have been capable of producing such sites as the sphinx (which the Egyptians may have later modified), or Gobekli Tepe, is not preposterous. In fact, it actually has some explanatory power where the sphinx erosion is concerned. Most geologists seem baffled in trying to explain it otherwise. And geologists know one thing really well ....

@Piratefish I haven't, Ancient Egypt really isn't my field.

Agreed. I very much prefer my dates to be organic, and breathing.