| Summary: | This paper examines the significance of large peat blocks in Trout Beck, an upland gravel-bed river in northern England. An inventory was made of all in-channel peat blocks over a 1.5 km reach of the river in order to characterise the distribution of the blocks, and benthic organic matter and periphyton were sampled from the gravel around an isolated in-channel peat block over a period of four months. Three suspended sediment samplers were installed adjacent to the block to provide estimates of organic drift. At reach scale, peat blocks can be traced to local sources of river bank erosion and show strong downstream fining trends. Analysis of organic matter fluxes indicates that large amounts of peat are eroded from blocks and this substantially increases local organic drift. Microscopic analysis of organic matter particles demonstrates the overwhelming dominance of allochthonous peat in suspension (~ 75 %). Some of this is deposited locally, but in general the amount of organic matter in the drift is substantially greater than that stored in the gravel bed. Therefore, although eroded peat is abundant in the channel system, it is easily transported by the river and thus contributes little to local benthic organic matter storage.
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