Does Vintage Iowa Map Show Where Ioway Leader Mahaska Was Killed?

We spotted this map in a Des Moines antique shop.  It is fully illustrated, dated 1934, and seems to indicate the site of Ioway Chief Mahaska's death.  He is also known as White Cloud.

Mahaska was assassinated in 1834 by Ioway warriors angered by his cooperation with the American goverment.  The exact site of his death is a mystery, but it is thought to be near the Nodaway River in either Montgomery or Cass County Iowa.

Click on the map above to view a larger image.