I own a building that was part of an old sawmill built on the Mississippi in Minneapolis in 1892, so I have an interest in the history of logging and sawmills. Over the weekend I was looking for pictures and found this one.
It's a raft made up of "strings" of logs. The bow was tapered to try to minimize damage when the raft struck the bank.
If you look closely, not only is there a woman in an apron, and a dog standing on his back legs, but there is a baby!
These rafts were sometimes made up of "cribs" of sawn lumber. From Minneapolis, lumber was rafted as far as St. Louis.
This photo is from Oregon.