What did the chumash Indian use to make canoes waterproof?

The Chumash Indians used a type of tar known as "asphaltum" to make their canoes waterproof. This natural tar, sourced from local seeps, was applied to the seams and surfaces of their wooden canoes, ensuring they were sealed against water. Additionally, they sometimes used the inner bark of certain trees as a lining to enhance durability and waterproofing. This technique allowed them to create sturdy vessels suitable for navigating coastal waters and rivers.