Monday, May 4, 2009

Balsa Rafts Permitted Ancient American Trading

Dutch envoy Joris van Spilbergen sketched this South American balsa raft in 1619.

An MIT doctoral candidate and her colleagues may have solved the mystery of why a specific style of ancient metalwork appears in South America and in western Mexico, but nowhere in between. Leslie Dewan contends Ecuadorean traders a thousand years ago sailed regularly to western Mexico and back ~ a round trip of 3,800 miles ~ on sail-bearing balsa rafts.

According to Discover Magazine:

Archaeologists have long wondered why copper work and other metalwork in a style typical of ancient South America appears in western Mexico but nowhere in between the two areas. This absence suggested a sea-based trade, so Dewan’s group decided to explore whether such lengthy voyages were feasible.

They based their mathematical study of seaworthiness on 16th-century European explorers’ descriptions of Native American trading vessels in western Mexico. The explorers wrote of seeing rectangular, two-sailed vessels made of balsa, a wood native to Ecuador, tied together with a hemplike fiber. Reaching about 35 feet in length, the rafts could probably have borne up to 30 metric tons of cargo—as much as 19th-century barges did in the Erie Canal.

Dewan’s team also evaluated the role of wind and water currents, concluding that the traders may have spent a few months in Mexico and returned when currents shifted. Meanwhile, her team is preparing to construct an actual-size model for the trip from Ecuador to Mexico, as they theorize it was done 1,300 years ago.

Click here for the Discover Magazine article.
Click here for Leslie Dewan’s description of her project.
Click here for a similar Ecuadorian project called the Manteno Expedition.

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