Abstract The importance of extrinsic drivers of fluvial system behaviour (climate, tectonics, eustatic sea level) over Quaternary timescales is well documented. However, comparatively fewer studies have been reported concerning the significance of more localised changes at reach to sub-catchment scale, over these extended (10 4 –10 6 years) timescales. In this paper we examine the Early Pleistocene sedimentary record of the palaeo-Hudut River and compare it with the record from the trunk river into which it drains, the Gediz River of Western Turkey. Both the Gediz River and the Hudut River were subjected to major localised disruption during the Early Pleistocene as a consequence of volcanism but their respective responses to these events appear to differ. Observations are reported from the sedimentary sequence buried beneath the lavas which cap the Burgaz plateau. These sediments record a remarkable amount of detail for a significant period of the Early Pleistocene. These suggest that the palaeo-Hudut system responded largely to the creation and failure of downstream lava dams, both through channel incision and subsequent filling, and via route diversions around lava dams and their associated lakes. In contrast, the Gediz terrace record appears to demonstrate a river which was able to accommodate these changes more readily and hence, continue to undergo sedimentation–incision cycles consistent with a climate forcing.