In quantitative fields of science, theories are proven. It is the collective of thousands of attempts at the experiment all replicating the same results, built off the principles of more elementary theories. Same thing with geology. Archaeology is a bit more speculative, but archaeologists use the limited information available to create a comprehensive timeline. While it may never be 100% correct, it’s a best guess until new peer-reviewed evidence comes along.
The BEST example of this is American archaeology. Our knowledge is constantly changing and we’re beginning to use Native American oral tradition to better our understanding. Some of the most interesting discoveries are rather recent like the Drop 45 “henge” discovered at the bottom of the Great Lakes.