Looking around on Google Maps, one can zoom in on the banks of the Oder river between Germany and Poland and find quite an extensive series of curious repeating land features along much of the river banks that resemble bones along a spine, for example at 52°22'56.1"N 14°32'46.2"E and 52°05'43.6"N 14°43'00.1"E. What are these land features and how are they formed?

Second picture

  • $\begingroup$ See a picture of those spines at River Groynes/ Wing Dams $\endgroup$
    – Max Jasper
    Nov 29, 2021 at 5:07
  • 1
    $\begingroup$ Identical features have been built along the Elbe river between the small City of Riesa in Saxony and the mouth of the river. $\endgroup$
    – Erik
    Nov 29, 2021 at 9:58

1 Answer 1


River Groynes or Wing dams which help to maintain a navigable channel by increasing river scour along the channel for shipping, reducing the need for dredging. They may also help reduce ice jamming.


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