And its commenters as well! Thanks, guys. I had never heard of "revetment."

Mr de Kam. are trees and branches still used this way in the Netherlands, or have the Dutch moved on to other materials?

Nah, I still think it's a really large placemat.

Amazing!

I know what it is because an episode of Dirty Jobs featured people STILL doing this very thing to rivers today.

We have a winner! It took only 29 minutes for Dirck the Noorman to come up with the magic word, "revetment." And only 10 minutes for Tom in Denver to hit on the general idea. Original caption for this Detroit Publishing image:

"Cambridge, Missouri. Revetment work on the Missouri River. Weaving the mat."

After the mat is woven and sunk, it's paved with stones.

They're weaving a mat or "revetment" to stabilize the bottom or shoreline of a lake or river. Dikes were often built on top of revetments like this.

Example:
http://www.mvn.usace.army.mil/eng/ci/concrete.asp

They're building a willow mat to control the Mississipi river.

More pictures of the process here:

http://wiki.cincinnatilibrary.org/index.php/River_Construction

The photo at the very bottom shows a completed mat that looks a lot like the one being constructed here.

They're weaving a huge fish net starting from right and going towards left - having water making it stronger in the long run as well?

Who knows.

For me here in the Netherlands it is obvious what is going on in this photo: The man are weaving the branches of young trees to make a protective structure that is used to enhance the strength of a dyke to keep the high water out.

I would guess they are harvesting some sort of sea grass to use for weaving baskets. Maybe off the Georgia coast?? Circa 1890's??

It appears that the work crew is weaving a shore-protection mat to prevent erosion on a levee. Probably along the Mississippi somewhere.

Seems we're somewhere way down south, bundling sugar cane and loading it on a barge to send to market. Do I have a winner?