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Drainage divide migration alters the geometry of drainage basins, influencing the distribution of water, erosion, sediments, and ecosystems across Earth’s surface. The rate of divide migration is governed by differences in erosion rates across the divide and is thus sensitive to spatiotemporal variations in tectonics and climate. However, established approaches for quantifying divide migration rates offer only indirect evidence for the motion of the divide and provide only migration rate averages. Consequently, transience in divide migration cannot be resolved, hindering the ability to explore environmental changes that drive the dynamics of such potential transience. Here, we study a set of datable terraces identified as markers of paleo-divide locations, which provide direct evidence for the paleo motion of the divide. The location and age of the terraces reveal intermittent divide migration at timescales of 10⁴to 10⁵y, with phases of rapid migration—at rates more than twice the average—which coincide with documented regional paleoclimate fluctuations. These findings highlight the intermittent nature of divide migration dynamics over geomorphic timescales and its potential sensitivity to climate changes, underscoring the impact of such changes on the planform evolution of drainage basins. 

Abstract Escarpments and cliffs (hereafter termed escarpments) form topographic barriers that influence the spatial patterns of climate and biodiversity. The inherent extreme slope change across the escarpment edge promotes escarpment retreat over time. Typically, escarpments are divided into arch‐ and shoulder‐types. In arch‐type, the drainage divide is located inland, and knickpoints, located where channels flow across the escarpment, can retreat and embay the escarpment. In shoulder‐type, the divide aligns with the escarpment edge, a setting expected to cause a slow and uniform escarpment retreat, preserving their integrity as barriers through time. However, observations from around the globe reveal shoulder‐type escarpments are associated with deep embayments (i.e., alcoves) that destroy the linear appearance of the escarpment front. Yet, the processes that produce and sustain these embayments remain largely unexplored. Embayments of shoulder‐type escarpments typically occur along reversed channels which were part of the antecedent drainage that used to flow away from the escarpment but now flow toward it, often resulting in a valley confined drainage divide called a windgap. Here, we hypothesize that feedback between knickpoint retreat and windgap migration away from the escarpment along reversed channels can sustain escarpment embayments, and use topographic analyses and numerical simulations to explore this hypothesis. Our analyses, focused on field sites in the Negev Desert, show that embayments of shoulder‐type escarpments can be sustained through the hypothesized feedback, and quantify the sensitivity of this feedback to geomorphologic and lithologic parameters. Results suggest that this feedback may explain some of the global variability of escarpment morphologies.