Conversation so far:
What was the origin of the Olmec?
The beginnings of Olmec civilization have traditionally been placed between 1400 and 1200 BCE. It seems that the Olmec had their roots in early farming cultures of Tabasco.
What can you tell me about the Olmec at El Manati?
Past finds of Olmec remains were ritually deposited at El Manati shrine.
How did the Olmec start?
It seems that the Olmec had their roots in early farming cultures of Tabasco, which began between 5100 BCE and 4600 BCE.
What technologies did the Olmec have?

Question: What's alluvial soil?
Self-contained rewrite: What is alluvial soil?