Two-part Arrows

Two-part arrows were a weapon of war.  I read about these in some of the histories of Native Americans in California, but did not really understand what they were, until I saw this display at the Calaveras Big Trees Visitor Center.

The base arrow is hollowed out at the top, and the arrow with the point slides into this.   They are effective because if the man pulls the arrow out, the base remains in the flesh.  Or if an animal happens to scrape an arrow off, the base again remains in the flesh.  This makes the arrow more deadly.