<< The first study of the way logs become pinned in rivers reveals that those seemingly trapped in a logjam move steadily, if slowly, downriver. >>
<< One of the lesser-known consequences of forest fires is logjams—river channels clogged with wood. The mechanism is straightforward. Forest fires create vast areas of dead wood. During the winter, heavy snow leads to avalanches that push thousands of the burned logs to the bottom of river valleys, where they enter the water. When the logs stretch across the river, from bank to bank, the river can no longer flow. It is this formation that has long captured the public imagination: the word "logjam" has come to mean a situation in which movement, physical or otherwise, is impossible. >>
Logjams aren’t really jammed at all, say geoscientists. Tech Rev - Emerging Technology from the arXiv. Nov 19, 2019
https://www.technologyreview.com/s/614724/logjams-arent-really-jammed-at-all-say-geoscientists/
Nakul S. Deshpande, Benjamin T. Crosby. Logjams are not jammed: measurements of log motions in Big Creek, Idaho. arXiv:1911.01518v1 [physics.geo-ph]. Nov 4, 2019.
https://arxiv.org/abs/1911.01518