Question

How does the existence of a site like Cactus Hill demonstrate the challenges that archaeologists face when making theories

Answer 1

Cactus Hill site has human remains that have been dated to around 20,000 years ago. Given its location in Virginia shows that human beings had reached America earlier than this. This contradicts the theory that postulates humans came to America from Siberia through the modern day Bring Strait. The theory asserts that at the end of the Ice age humans were able to cross to America through the Beringia land bridge and other means such as canoes and rafts around 10,000 years ago. 

Answer 2

Archaeologists base their conclusions on artifacts found over a large area. Exact dates cannot always be determined, and scientists don't always agree on the data provided by the evidence. New findings may contradict theories that have already been accepted.