ABSTRACT Extensive glaciers covered the High Atlas mountains in Morocco during the late Pleistocene. On the northern escarpments of the Marrakech High Atlas, a series of cirques perched at ~3000–3500 m above sea level (asl) fed their valley glaciers that, in some cases, extended to as low as 2000 m asl. Cosmogenic exposure dating with 10 Be and 36 Cl has shown that at least three phases of glaciation are preserved in glacial deposits over the last glacial cycle at 50, 22, and 12 ka, which appear to correlate with marine isotope stage (MIS) 3, the global Last Glacial Maximum (LGM), and the Younger Dryas chronozone. This geochronological framework is sufficiently robust to allow for time-constrained glacier-climate reconstructions. The glaciers associated with these three phases of advance had equilibrium line altitudes (ELAs) of 2761 m asl (ca. 50 ka), 2919 m asl (ca. 22 ka), and 3213 m asl (ca. 12 ka). Glacier-climate modeling suggests that all of these phases were driven by both colder temperatures and wetter conditions than today. The dominant moisture supply to these glaciers in all phases would have been sourced from Atlantic depressions. The influence of an extended and enhanced West African monsoon on glacier development during African Humid Periods is unlikely to have been a significant influence on glacier dynamics. The climate conditions associated with the three glacier phases indicate sustained moisture supply to the highest mountain areas when records from other areas, such as the Middle Atlas lakes and marine sediment cores offshore, indicate marked aridity.

ABSTRACT Climate during the Last Glacial Maximum (LGM) varied substantially across North America, strongly influencing changes in plant and animal distributions and causing variations in the timing and relative magnitude of ice expansion and recession. The Olympic Peninsula is a mountainous maritime terrain in northwestern Washington, where the climate today is most strongly influenced by Pacific weather systems. However, what about during the LGM, when ice sheets covered most of northern North America? Fossil beetle assemblages of LGM age contain species that currently inhabit riparian and lacustrine habitats in the boreal zone of Canada and Alaska, and in higher elevations in the Cascades and Rocky Mountains. They include three Olophrum species that today are unknown from the Olympic Peninsula. Olophrum consimile is especially well represented, and its occurrence today above 1000 m elevation in the Cascades of northern Washington State indicates summers during the LGM would have been at least 4 °C cooler than today. The absence of wood-boring beetles, in contrast to assemblages from deposits correlating with marine isotope stage (MIS) 3, supports an open rather than a forested landscape. The insect fossils also include an undescribed species of a blind trechine ground beetle, likely endemic to the Pacific Northwest with biogeographic affinities to Asia. Pollen and plant macrofossil evidence for a Sitka spruce and mountain hemlock parkland with similarities to the vegetation of modern southeast Alaska also supports an interpretation of a climate with summer temperatures ~4 °C cooler than today. Both the vegetation and the insects provide evidence that the climate was wet with persistent snow cover and not as dry as has been reported from the Puget Lowland to the east. Glacial geology provides evidence that during the colder climate of the LGM, mountain glaciers advanced down the western valleys of the Olympic Peninsula to the lowlands but not as far as they had extended during MIS 3. The amount of climatic cooling on the Olympic Peninsula during the LGM was less than at similar latitudes in midcontinental or eastern North America, indicating a strong modulation of climate by the Pacific Ocean.

ABSTRACT An extensive kame-terrace sequence in the middle Rangitata Valley reveals ice-volume fluctuations spanning the last (Otiran) glaciation. Stratigraphic and sedimentologic characteristics document lateral ice-marginal processes and provide context for luminescence dating. The sequence provides novel and complementary data on glacier ice thickness, which fluctuated substantially throughout the Otiran glaciation. Thick ice constructed one of the highest kame terraces (540 m above the valley floor) ca. 68 ka and thinned nearly 500 m to the valley floor by ca. 53 ka. Following an episode of ice thickening to an unknown elevation, ice again thinned to the valley floor by ca. 44 ka. Ice thickened to its greatest late marine oxygen isotope stage (MIS) 3 extent of 480 m by ca. 37 ka, and thinned to 230 m by ca. 31 ka. The final ice expansion, to 260 m, occurred by ca. 25.5 ka, and the ice fluctuated and thinned to 240 m at ca. 22–20 ka and to 170 m at ca. 21–17 ka. Published cosmogenic radionuclide (CRN) ages indicate surface stabilization near the valley floor (55 m) by ca. 18 ka. This ice-thickness chronology provides an independently derived ice-volume record that is consistent with local and regional glacial chronologies. The site, lying between the Mackenzie Basin and the northern Canterbury Plains drainages, displays a chronology with advances correlative in part with each of those regions. Maximum ice extent occurred 70–65 ka in the Rangitata Valley and the Mackenzie Basin, while the subsequent ice expansion ca. 37 ka is similar in timing to chronologies in both the Rakaia Valley to the north and the Mackenzie Basin to the south.

ABSTRACT In this study, we present a composite δ 18 O and δ 13 C record obtained from four speleothems from the Grotta Grande del Vento Cave, located within the Frasassi karst system, northeastern Apennines of central Italy. The ages were determined by U-series analysis, employing thermal ionization mass spectrometry (TIMS), and the composite isotopic profile covers most of the time period from ca. 95,000 yr B.P. until ca. 10,000 yr B.P., including the last part of marine isotope stage (MIS) 5, most of the last glacial (MIS 4–2), and the earliest Holocene (MIS 1), with a hiatus lasting from ca. 65,000 to ca. 55,000 yr B.P. We compared this record with other speleothem records from the Eastern Mediterranean, with caves from western Portugal, with two marine records from the Eastern Mediterranean and the Aegean Sea, and with the North Greenland Ice Core Project (NGRIP) ice-core record. The Frasassi speleothem record provides further insight for a wider regional understanding of the paleoclimate record through the discrepancies and similarities between the northeastern Apennines of central Italy and the Western, Eastern, and northeastern Mediterranean regions. The time interval between ca. 86,000 and 83,000 yr B.P. shows low δ 18 O values in the Western and Eastern Mediterranean speleothems and the marine records. This period coincides with sapropel (S3) and is associated with increased hydrological activity and warming. On the other hand, Frasassi speleothem δ 18 O data do not show a similar low trend, suggesting that increased hydrological activity either did not reach the Frasassi region and/or the region received rainfall from other sources and/or the proportion of winter-summer rainfall was different. Another interval in which different conditions prevailed in the Frasassi region is during the transition from MIS 5 to glacial MIS 4, from ca. 83,000 to 65,000 yr B.P., when Frasassi speleothem δ 18 O values decreased, whereas all other records show a clear increase in δ 18 O. Comparison with the NGRIP record suggests that Northern Hemisphere temperature changes are reflected in Frasassi speleothem δ 18 O fluctuations during this interval. A major pronounced isotopic event associated with warming and pluvial conditions during the last glacial evident in the entire Mediterranean region between ca. 54,500 and 52,500 yr B.P. is recorded also in the Frasassi speleothem isotopic profile. This event is followed by a transition from wet and warm climatic conditions to cold conditions. The end of the last glacial is associated with climate instability, evident mainly from the very large oscillations in the Frasassi δ 13 C record. The transition from the last glacial to early Holocene is characterized by a decreasing trend in δ 18 O and a sharp increase in δ 13 C values.

Abstract 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.