Multnomah Indians aka Flatheads

The Indians that Sacagawea and the Corps of Discovery met on the other side of the Celilo falls were different from the Indians they had met before.

http://hugefloods.com/ColumbiaGorge.html

One of the tribes was the Multnomah Indians also known as the "Flatheads" for the way they shaped their babies' heads in a cradle board to make their foreheads slope toward the back of their heads.

Source: Unknown (Pinterest)

Captain Clark's Journal via http://sauvieisland.org/visitor-information/history/

The Multnomah AKA Flatheads, were a  tribe of the Chinook Indians who lived in cedar log houses 30 yards long and a dozen yards wide. Each family had its own entrance and fire pit. 

They tied their babies to a flat board, with another piece of wood fixed across the baby’s brow that put pressure on the skull to flatten it from the crown to nose. This feature was respected and seen as a superior beauty feature. 

Their way of dress was different, too. Women wore a fringed skirt of cedar bark and anointed their hair with fish oil.