Of the several types of Quaternary deposits formed by glacial, alluvial and mass-wasting processes, with vast climatic and tectonic significance lake deposits stand out prominently in the Indus valley around the town of Leh. We studied a number of palaeolake deposits between the Zinchan–Indus confluence and Shey village and carried out optically stimulated luminescence (OSL) quartz dating of samples from critical sections. Our results indicate that, during the late Quaternary, the Indus River was dammed at least twice in the narrow gorge downstream of Spituk Gompa, forming a reservoir up to 35 km long in which 20–68 m thick sediments were deposited under fluvial and lacustrine environments. During the older phase, the Indus was blocked by debris of moraines/landslides in the narrow zone near the Zinchan–Indus confluence. The resulting lake existed between c. 125 ± 11 and 87 ± 8 ka during marine isotopic stage (MIS) 5. No evidence of damming material is preserved. Present-day elevations of lake deposits suggest a possible extension of the lake up to Ranbirpura upstream. After the lake breach, the Indus River was again dammed near Phey village by the advancing alluvial fan of the Phyang River. This lake, extending up to Karu, formed at c. 79 ± ka. The lake existed in this phase during c. 72–49 ka, during cold-stage MIS-4. The lake was breached after c. 46 ± 3 ka, however.

In glacier-fed Baspa River valley, Late Quaternary climatic changes are archived in the terraces, fan and landslide deposits. An initial optically stimulated luminescence (OSL) based stratigraphy of these deposits is developed to deduce geomorphic evolution and palaeoclimatic changes. The data show large alluvial fan progradation around Sangla till c. 45 ka (middle of marine isotope stage 3 or MIS-3) due to glacial retreat and readjustment of glacigenic sediment under warm and humid conditions followed by incision. During the end phase of MIS-3 (>23 ka), intensified precipitation blocked the river course near Sangla and Kharogla by rock avalanches and imposed lacustrine conditions which recorded sedimentation until the beginning of Holocene (c. 11.4 ka). Reduced sedimentation in these lakes during the last glacial maximum (LGM) c. 23–18 ka suggests a cold and arid climate, whereas increased sedimentation during c. 18–11.5 ka indicates a warm and humid climate post-LGM. A palaeolake breach occurred during early Holocene and incision continued throughout the Holocene, with a pulse of fluvial aggradation during c. 9.1–6.5 ka over lacustrine remnant. In the upper reach of the valley (Chitkul area), coeval aggradation continued from >28 ka until c. 19 ka (MIS-3 to LGM) under cold and relatively arid conditions. This study emphasizes that Late Quaternary geomorphic evolution of Baspa valley is well synchronous with glacial fluctuations and the rapid response of the glacifluvial system to Indian summer monsoon (ISM) dynamics.