**Logjams are not jammed:
measurements of log motions in Big Creek, Idaho**
We all have experience of things in our lives becoming crowded and stuck (traffic, queues for a coffee)- we frustratingly call them 'logjams'. When wood falls into rivers, they create literal logjams as individual pieces of wood clog together and frustrate the flow of moving water. In many cases, wood is deployed intentionally to restore habitat and increase the health of a river system. However, the story is not so simple. An ambitious field campaign measuring the movement of a naturally-occurring logjam in Idaho (composed of thousands of logs) reveals that despite the namesake, the logjam is not jammed. Instead, the feature 'breathes' and deforms very slowly in concert with the rise and fall of water - supplied to the river by snow melting within the basin. Patterns of movement within the logjam are stark: as water level rises deformation is globally distributed and as water falls, the movement becomes patchy as logs settle under gravity. These results indicate that accumulations of wood in rivers may be more dynamic than we thought - albeit slowly. This can have a critical influence on the conditions necessary to fully mobilize wood - when it can be a serious hazard to bridge piers, infrastructure and communities.
![Downstream perspective of Big Creek logjam][1]
[1]: https://files.osf.io/v1/resources/y8uz6/providers/osfstorage/5dc0428daf84c3000beb5fe5?mode=render
