Accumulated drift remains intact for years unless removed, and sometimes is remobilized and transported downstream. Typical logs observed in this study lay approximately horizontal in the water, were exposed over their full length or nearly so, and did not rotate about a horizontal axis. Logs on the surface are not consistently aligned with the flow or across it, but rotate under the influence of large moving eddies. 118K GIF version of this photograph Figure 9. Logs floating along the center of the Harpeth River at Wray Bridge, Williamson County, Tennessee.
Drift commonly aggregates into short-lived clumps.
Most transported aggregations observed in this study were broken apart by turbulence, or when they struck a stationary object such as a pier or an accumulation of drift. Floating drift was typically observed in a surface-convergence zone, usually in the thread of the stream. In moderate bends, drift was observed more often along the thread between the center of the channel and the outside bank than in contact with bank vegetation. 3K GIF version of this diagram Figure 10 . Generalized plan view of the path of floating drift in a meandering river.