Abstract In this work, we present a description of the sedimentary fill of a well-exposed lacustrine succession in the Ecuadorian Andes. The Guayllabamba basin is an intermontane basin located in the Andean range of Ecuador, and part of its sedimentary history is represented by a volcanically influenced c. 100 m-thick lacustrine unit of Pleistocene age. We create a stratigraphic cross-section from the eastern to western lake margins and identify 19 facies that were used to carry out a palaeoenvironmental reconstruction. The Guayllabamba palaeolake was developed in a tectonic depression surrounded by volcanoes and it was filled with sediments derived from the erosion of the volcanic edifices, the reworking of unconsolidated pyroclastic deposits and deposition of pyroclastic currents into the lake. The lake shows a deepening trend, passing from shallow deltaic sedimentation to varved diatomites with turbidites. Abundant ash-fall beds, monolithological pumiceous deltaic sequences and pumice-dominated thick ignimbrites show the impacts of volcanism on lacustrine sedimentation within this basin. Soft-sediment deformation and gravity flow deposits are common owing to the intrabasinal tectonic activity and to the intrusion of a lava body. Aulacoseira -rich diatomites dominate the background lake sedimentation. The outcrops of the Guayllabamba basin are outstanding examples of the interaction between volcaniclastic and lacustrine sedimentation.

ABSTRACT This field guide provides an updated synthesis of the stratigraphy and chronology of glacial deposits in central Indiana near the southern limit of glaciation in the midcontinent. Central Indiana contains evidence of multiple glaciations—deposits from the last two glaciations (Oxygen Isotope Stages [OIS] 2 [Wisconsin Episode] and 6 [Illinois Episode]) have been the focus of recent stratigraphic and chronologic investigation. New radiocarbon and optically stimulated luminescence (OSL) dating from outcrop and core has refined the timing of OIS 2 and OIS 6 ice sheet advances, outwash/slackwater aggradation, glacial lake formation, and eolian activity. Radiocarbon ages within or below late Wisconsin till from three sites within 5 km (3 mi) of the late Wisconsin maximum limit indicate an age of 24.0 k cal yr B.P. for maximum OIS 2 ice sheet extent in central Indiana, consistent with chronology from Illinois and Ohio. A subsequent >50 km (31 mi) readvance (21.6 k cal yr B.P.) across central Indiana came within 10 km (6 mi) of the maximum limit and in the western part of the field-trip area, terminated in glacial Lake Eminence. The start of outwash aggradation and associated slackwater sedimentation in the West Fork White River valley and tributaries began ca. 27 k cal yr B.P. and continued until ca. 20.5 k cal yr B.P., representing the timing of ice sheet advance into and out of the paleo–White River drainage basin. Ice sheet advance and retreat rates average ~40 m/yr before and after the global Last Glacial Maximum (ca. 26−21 k cal yr B.P.) when ice was within ~50 km of the late Wisconsin maximum. OSL dating of pre-Wisconsin outwash and glacio-lacustrine sediment return ages between ca. 218 and 127 ka, confirming deposition during OIS 6. These ages document spatially complex sedimentation in bedrock valleys beyond the Wisconsin limit.