The Calico Early Man site is just a short distance from the Calico Ghost Town. This is one of the more unusual parks in that it is an actual working archeological site. The idea behind Calico is that it may be the earliest known place in america where evidence of humans has been found.
The site dates back more than 200,000 years from today and the ancient Mohave desert would have actually been an inland sea that could have made this an attractive area to live. Calico is also unique because this was the only place in the USA explored by the famed Louis Leakey who mounted an expedition with support from the National Geographic Society.
The actual scientific work will give pause to anyone thinking they want to work as an archaeologist: while site has pretty views of the valley, there is a lot of hard digging, pain-staking sorting of rocks, and the hot sun. You need to be committed.
The site is not without considerable controversy: the basic claim are that these 'geofacts' rocks found at the site are examples of tool working and a clear indication of early humans. Many experts argue that these rocks are actually just naturally occurrences are merely look like artifacts.
I do a lot of fossil collecting and used to regularly search for native American stone artifacts we found on the Rappahannock river. Over the years we've develop a sharp eye and learned to find stones that were worked by ancient people. So you can imagine my excitement when 5 minutes into the walk to the site I find what is obviously a piece of stone that has been worked by human hands! A few minutes later it was another - and then another. And another. In the end there were numerous ones that could be found. (You can't take any of the rocks.) I've found more fossils in a concentrated location, but never any place with so many human artifacts. In fact, the number was staggering but the markings on the stones were pretty clear.
After I left the site I did some internet research to better understand the controversy. In the end everyone will have to make their own conclusions, but in my mind there is just no way that a small number of people could have produced that many artifacts; it has to be some natural process. Most of the experts have that opinion as well. No question that the site is intriguing, however, and it was neat to visit.