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Quaternary Science Reviews 28 (2009) 2165–2212

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Quaternary Science Reviews

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Glaciation in the Andes during the Lateglacial and Holocene

Donald T. Rodbell a,*, Jacqueline A. Smith b, Bryan G. Mark c a Geology Department, Union College, Schenectady, NY 12308, USA b Department of Physical and Biological Sciences, The College of Saint Rose, Albany, NY 12203, USA c Department of Geography, The Ohio State University, Columbus, OH 43210, USA article info abstract

Article history: This review updates the chronology of Andean glaciation during the Lateglacial and the Holocene from Received 23 March 2008 the numerous articles and reviews published over the past three decades. The Andes, which include Received in revised form some of the world’s wettest and driest mountainous regions, offer an unparalleled opportunity to 29 March 2009 elucidate spatial and temporal patterns of glaciation along a continuous 68-degree meridional transect. Accepted 30 March 2009 The geographic and altitudinal extent of modern glaciers and the sensitivity of both modern and former glaciers to respond to changes in specific climatic variables reflect broad-scale atmospheric circulation and consequent regional moisture patterns. Glaciers in the tropical Andes and in the mid-latitude Andes are likely to have been far more sensitive to changes in temperature than glaciers in the dry subtropical Andes. Broad-scale temporal and spatial patterns of glaciation during the Lateglacial are apparent. In the southernmost Andes, the Lateglacial chronology appears to have a strong Antarctic signature with the best-dated moraines correlating closely with the Antarctic Cold Reversal. The southernmost Andes do not appear to have experienced a significant ice advance coeval with the Younger Dryas (YD) climatic reversal. At the other end of the Andes, from w0to9N, a stronger YD connection may exist, but critical stratigraphic and geochronologic work is required before a YD ice advance can be fully demonstrated. In the central Andes of Peru, well-dated moraines record a significant ice readvance at the onset of the YD, but ice was retreating during much of the remaining YD interval. The spatial–temporal pattern of Holocene glaciation exhibits tantalizing but incomplete evidence for an Early to Mid-Holocene ice advance(s) in many regions, but not in the arid subtropical Andes, where moraines deposited during or slightly prior to the Little Ice Age (LIA) record the most extensive advance of the Holocene. In many regions, there is strong evidence for Neoglacial advances in the interval between 1.0 and 2.5 ka. Moraines that correlate with the LIA of the Northern Hemisphere are seen in all presently glacierized mountain ranges; most of these date to within the past 450 years. Outboard of these moraines in many regions are moraines of a slightly more extensive advance that occurred several hundred years prior to the onset of the LIA. Priorities for future work include filling in several prominent spatial gaps in the distribution of chronologic studies. For the Lateglacial these gaps include the arid regions of northern Chile and Argentina, the southern Peruvian Andes between 11.5and 13.5S, and the Andes of northern Peru and southern Ecuador between 3 and 9S. Areas in need of better representation in regional datasets of Holocene glaciation include all of the Andes north of the Equator. Specific chronologic priorities include the need for close bracketing radiocarbon ages for purported Early and Mid-Holocene moraines, and the increased application of cosmogenic radionuclide dating to Lateglacial and Early Holocene moraines that are already constrained by maximum-limiting radiocarbon ages. Ó 2009 Elsevier Ltd. All rights reserved.

1. Introduction these publications (Clapperton, 1983, 1993a; Mercer, 1983, 1984) reviewed evidence for, and the timing of, glaciation throughout This review builds on a series of summary articles, which span South America over the entire Cenozoic. Others reviewed evidence more than 30 years, on the glacial history of the Andes. Several of for speciﬁc time intervals and in speciﬁc geographic sectors. For example, whereas Mercer (1976, 1982) provided a comprehensive review of Holocene glaciation in southern South America, Clap- * Corresponding author. Tel.: þ1 518 388 6034; fax: þ1 518 388 6417. E-mail addresses: [email protected] (D.T. Rodbell), [email protected] perton and Sugden (1988) reviewed evidence of Holocene glacia- (J.A. Smith), [email protected] (B.G. Mark). tion throughout the Andes, Seltzer (1990) reviewed the record of

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Lateglacial and Holocene glaciation in Peru, Clapperton and Seltzer elevational control on precipitation in this region likely yields steep (2001) reviewed evidence for glaciation during marine isotope vertical accumulation gradients, and thus glaciers here may have stage 2 (MIS 2) throughout the Americas, and Mark et al. (2004) and the steepest mass balance gradients of all Andean glaciers. High Smith et al. (2008) summarized the Late Quaternary records from precipitation in the accumulation areas of glaciers in this region Ecuador, Peru, and Bolivia. Finally, Schubert and Clapperton (1990) coupled with the relatively low elevation of the 0C isotherm reviewed the Late Quaternary record of glaciation in Ecuador, results in numerous tidewater and freshwater calving glaciers, Colombia, and Venezuela. All radiocarbon ages referred to herein as including the lowest latitude tidewater glacier on Earth, the San ‘‘ka’’ refer to thousands of calibrated 14C years BP, with BP equal to Rafael Glacier, that drains the west side of the North Patagonian Ice AD 1950, and are thus equivalent to radionuclide and luminescence Field (NPIF) at w46.7S(Warren, 1993). ‘‘ka’’ ages. Calendar ages over the past two millennia are reported in years AD. 2.2. Glaciers in the dry subtropical Andes The Lateglacial (defined for the purposes of this paper as the interval between w16.7 and 11.5 ka (w14,000 and 10,000 14C yr BP) The Andean subtropics as generally defined extend from has attracted the attention of numerous workers and has been the w23.5Sto30S, but climatologically and glaciologically it is focus of several review articles. (Clapperton, 1993a,b) reviewed useful to consider the Andean subtropics as extending from w18S evidence for glacier oscillations during this time interval from the in the western Bolivian Andes to 29S in northern Chile. In the entire length of the Andes, and Heine (1993) focused his review on northern part of this latitudinal belt the western and eastern the tropical Andes. cordillera of the Andes are as much as w200 km apart, and The objectives of this review, in light of the abundance of between these two cordilleras lies the dry Bolivian Altiplano. summary articles noted above, is to provide an update on the Precipitation in this region is primarily derived from the tropical chronology of glaciation in South America over the Lateglacial and easterlies and occurs during the austral summer (Fig. 3B) in the Holocene, and to critically evaluate the database in terms of the association with the development of the South American summer degree of regional and interregional synchrony of events. We focus monsoon (Zhau and Lau, 1998), although south of 27S some on the past w17 ka because there have been numerous papers in moisture is occasionally derived from the westerlies (Ammann the last two decades that report on the timing of glaciation in the et al., 2001). In either case, little precipitation falls; mean annual Andes during this interval. In addition, several events such as the precipitation (MAP) is 440 mm on the summit of Nevado Sajama Antarctic Cold Reversal (ACR; e.g., Steig et al., 1998), Younger Dryas (6542 m a.s.l.) at 18.1S(Thompson et al., 1998) and w300 mm at (YD; e.g., Mangerud et al., 1974), and the Little Ice Age (LIA; e.g., w29S(Grosjean et al., 1998). Owing to the aridity of this region, Grove, 1988) occurred during this interval, and, though these modern glaciers do not exist between 18.5 and 27S despite events have been long recognized in high latitude regions, there is numerous summit elevations above 6000 m, with some as high as still considerable uncertainty and debate over their signature in 6700 m (Ammann et al., 2001), and an elevation of the 0 isotherm different parts of the Andes. that declines southward from w5000 to 4100 m a.s.l. (Klein et al., 1999; Grosjean et al., 1998). The few glaciers that do exist at the 2. Geographic and glaciologic setting northern end of the dry subtropical Andes are wholly above the 0C isotherm, and with ablation limited to sublimation, likely have The Andes span 68 of latitude (Fig. 1) from the northernmost very low vertical ablation gradients (Kaser, 2001). tropical Andes of Colombia (12N) to the temperate Andes of southernmost Chile and Argentina (56S), and include some of the 2.3. Tropical Andean glaciers driest and wettest mountainous regions on Earth (Fig. 2). Circula- tion patterns dictate regional moisture patterns, which in turn All of the northern Andes and part of the central Andes fall affect both the geographic and altitudinal extent of modern glaciers within the astronomical tropics (between 23.5N and 23.5S), and the sensitivity of both modern and former glaciers to changes where the mid-day sun reaches the zenith at least once per year in specific climatic variables. and never falls below 43 from the horizon. Within this latitudinal range, solar radiation receipts are consistently high throughout the 2.1. Temperate latitude glaciers of Chile and Argentina year, which results in both a small range of annual temperatures, one that is greatly exceeded by the diurnal temperature range South of 29S, westerly circulation dominates and precipitation (Benn et al., 2005; Hastenrath, 1985), and a small annual range in is derived from the Pacific Ocean. In the northern part of this region, the elevation of the 0C atmospheric isotherm (Klein et al., 1999). precipitation falls dominantly during the austral winter (e.g., Precipitation in the tropical Andes is derived from the tropical Puerto Mont, Chile; Fig. 2), whereas precipitation in the south- Atlantic Ocean via the tropical easterlies, and is transported to the ernmost Andes is more uniformly distributed throughout the year high Andes via convective circulation over the eastern tropical (e.g., Ushuaia, Argentina; Fig. 2). Strong orographic effects are Andes. The trajectory of the easterlies and the seasonality of apparent in precipitation trends in this region, with much less convection-driven precipitation are governed by the annual pole- precipitation falling on the eastward (leeward) side of the Andes ward march of the belt of convective activity during the late spring than on the western side. For example, in a west–east direction and summer months and the equatorward return during winter across the Andes, annual precipitation totals nearly 2000 mm at months. The outer tropics of the Southern Hemisphere (e.g., La Paz, Puerto Mont, Chile, more than 8000 mm on the summit of the Bolivia; 16S; Fig. 2) thus experience a single marked wet season Patagonian Ice fields (Escobar et al., 1992), and less than 200 mm at during the peak summer months (DJF for the Southern Hemi- Mendoza, Argentina. Since insolation and hence temperatures are sphere) whereas the humid inner tropics (e.g., Quito, Ecuador; much more seasonal at these latitudes, glacier ablation is generally 0.5S; Fig. 2) experience two wet seasons, one during the spring restricted to the summer season (Fig. 3A). Vertical ablation gradi- with the southward passage of the belt of convective activity and ents are most certainly steeper than those of the high, dry western one during the autumn with its northward return. In addition to the Andes of southern Peru, Bolivia, and northern Chile, but perhaps marked seasonality of precipitation, strong trans-Andean precipi- not as steep as those of the wet tropical Andes (Kaser, 2001). In tation gradients exist. The wettest parts of the tropical Andes are in contrast to lower latitude glaciers of the Andes, the strong the eastern foothills, where MAP can exceed 4000 mm (Hoffman, Author's personal copy

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80° W 60° 40°

Sierra Nevada de Mérida

Sierra Nevada de Cocuy

Papallacta Pass 0° Nevados Chimborazo & Carihuairazo

Cordillera Blanca Cordillera Huayhuash

t Junin Plain tropical easterlies

r Cordillera Vilcanota

u Quelccaya Ice Cap

)

r Cordillera Real

P (

d l

o b

20° m

u Cordillera Quimsa Cruz

mid-latitude westerlies Lago Llanquihue explanation

40° S ice

Patagonian Ice Fields area above 4000 m Lago Argentina Strait of Magellan area above 1000 m Tierra del Fuego lakes Cordillera Darwin

Fig. 1. South America with general atmospheric and oceanic circulation (large gray arrows) that affects Andean weather patterns, and the names of many of the mountain ranges mentioned (modiﬁed from Clapperton, 1983).

1975). In contrast, the western Andes experience much lower MAP, for much of the tropical Andes; Klein et al., 1999) varies considerably commonly <1000 mm (e.g., 650 mm for Huara´z, Peru; Fig. 2). across the Andes. Klein et al. (1999) documented modern glacier Tropical glaciers differ markedly from mid- and high-latitude snowlines several hundred meters below the 0C isotherm (snowline glaciers in the annual cycle of mass balance. Owing to the elevations from 4400–4700 m a.s.l.) in the wet eastern tropical Andes convective nature of precipitation, accumulation gradients on to over 1000 m above the 0 isotherm (snowline elevations 5800 m tropical glaciers are small (Benn et al., 2005). Likewise, the thermal a.s.l.) in the dry western Andes of southern Peru and western Bolivia. homogeneity of the tropics promotes ablation by melting in the lower parts of most glaciers throughout the year (Fig. 3C; Benn 2.4. Glacier sensitivity to climate change et al., 2005), and results in steep vertical ablation gradients (Kaser, 2001) with concomitantly high accumulation area ratios. Excep- Glaciers in different regions of the Andes are likely to have had tions to this relationship are those glaciers, discussed above, in the very different sensitivities to past variations in temperature and dry western Andean cordillera of southern Peru and Bolivia that precipitation. Glaciers in areas of high precipitation, where snow- exist entirely above the 0C isotherm; these glaciers ablate princi- lines are at or below the 0C isotherm, are likely to be especially pally by sublimation. sensitive to changes in temperature and insensitive to changes in The relationship between the elevation of the snowline of modern precipitation (Klein et al., 1999; Kaser, 2001). A small decrease in air tropical Andean glaciers and the 0Cisotherm(w4800–5200 m a.s.l. temperature below 0C during the accumulation season of these Author's personal copy

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Fig. 2. Mean monthly precipitation (mm) and temperature (C) data for selected stations along the Andes. Data are from the Global Historical Climatology Network and datasets range from 366 months (Bogota´) to 1133 months (Punta Arenas). Author's personal copy

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A dubbed these glaciers ‘‘thermally ready,’’ and Kaser’s (2001) sensitivity studies further revealed that these glaciers are especially sensitive to changes in atmospheric humidity, which affects the ratio between sublimation and melting on the ice surface. It is conceivable that glaciers in the subtropical Andes might advance in response to warmer air temperatures due to the dependence of accumulation convection, and thus precipitation, over the Altiplano on heating the ground surface during the austral summer months (Ammann et al., 2001).

ablation The calving glaciers of the mid-latitudes of Chile, though a distinct minority of all Chilean glaciers, pose signiﬁcant prob- B lems for those attempting to decipher a climatic signal from them. As with calving glaciers elsewhere (e.g., Mann, 1986; Porter, 1989), those of the southern Andes respond to a host of variables, many of which are not directly linked to climate. Warren (1993) cautioned that there must be an a priori assumption that calving

accumulation glaciers do not respond directly to climatic change, and that the ‘‘burden of proof’’ should be on the investigator attempting to decipher a climate signal from changes in the extent of such glaciers. ablation

C 3. Documenting and dating changes in the position of ice margins

3.1. Evidence of changes in ice marginal positions

accumulation Preserved end or lateral moraines and trimlines on bedrock are the only unambiguous evidence that a glacier achieved some degree of equilibrium for some period of time in a specific former position. A fundamental uncertainty in reconstructing glacial limits ablation is whether the ice marginal evidence records a distinct glacial 1 balance year readvance or simply a stillstand during ice retreat. Although the paleoclimatic reconstructions that derive from these two options austral summer austral winter are profoundly different, the only geomorphic evidence that can Fig. 3. Idealized mass balance characteristics of temperate glaciers of the Andes (A), distinguish between a readvance and a stillstand are cross-cutting outer tropical glaciers (B), and wet inner tropical glaciers (C); modified from (Kaser and moraines, and these have only rarely been reported (e.g., Rodbell Osmaston, 2002) and Benn et al. (2005). and Seltzer, 2000). This paleoclimatic uncertainty coupled with difficulties in dating moraines and trimlines, and the inherently discontinuous record of glaciation that moraines provide have led many workers (e.g., Karleń, 1976, 1981; Seltzer and Rodbell, 2005) glaciers would mean that the significant precipitation that does fall to look to sediment records from downvalley lakes as potential would fall as snow rather than rain, thus resulting in a potentially proxy records of upvalley ice extent. Several investigators have significant increase in a glacier’s net mass balance. interpreted increases in the concentration of clastic sediment in Kaser (2001) modeled the vertical mass balance profiles of cores as providing evidence for an interval of ice expansion and/or glaciers in the humid inner tropics, the subtropics, and the mid- moraine construction in the Andes (e.g., Ariztegui et al., 1997; latitudes, and evaluated the sensitivity of the equilibrium line Stansell et al., 2005; Polissar et al., 2006; Rodbell et al., 2008). altitude (ELA) to variations in precipitation, temperature, and net However, other sources of sediment such as the breaching of short wave radiation. Whereas modeled glaciers in both the humid upvalley moraine dams, subaerial or sub-lacustrine slope failures, inner tropics and the mid-latitudes are far more sensitive to and changes in the trajectory of inflow streams can significantly changes in temperature than those in the dry subtropics (discussed affect clastic sediment delivery to coring localities in alpine lakes. below), humid tropical glaciers experienced a 40% larger ELA Paraglacial sedimentation (Church and Ryder,1972) associated with response to temperature change and a 55% smaller ELA response to deglaciation can also be a significant source of clastic sediment to precipitation change than did modeled mid-latitude glaciers (Kaser, glacial lakes. Few workers have followed the examples of Leonard 2001). Humid tropical glaciers, with their steep mass balance (1986, 1999) or Rosenbaum and Reynolds (2004) to chemically or gradients, are also likely to respond to climatic change with little physically fingerprint glacigenic sediment. Thus, while sediment lag time, as demonstrated by the synchrony between hydrologi- cores may be far more readily dated, the interpretation of changes cally-derived mass balance estimates and observed variations in in upvalley glacier extent, and thus of climatic change, should be glacier terminus position (Kaser et al., 2003). viewed skeptically until it can be demonstrated that non-glacial A decrease in temperature would have very little effect on the sources of clastic sediment have been insignificant. As with calving glaciers in the high, dry western Andes of southern Peru, Bolivia, glaciers, the burden of proof should be on the investigator to and northern Chile. Cooling these glaciers, which already lie above demonstrate the linkage between a sediment record and the the 0C isotherm, would do little to add to their net mass balance. In activity of a nearby glacier. Thus, for this review we consider only contrast, a small increase in precipitation would dramatically moraines as providing unambiguous evidence of a former glacier’s increase the net mass balance of these glaciers; Messerli (1967) extent. Author's personal copy

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3.2. Lateglacial and Holocene moraines plants without eroding them. If rooted plants can survive being overridden by glacial ice in some circumstances, then we cannot Below we summarize results of numerous studies that employ assume a priori that all basal ages from upvalley lakes and peat a variety of methods to date moraines. These include biological lands are necessarily minimum-limiting ages for downvalley chronometers (dendrochronology and lichenometry), and radio- moraines. It seems likely, however, that organic matter preserved in metric and other geochemical-based methods. The most commonly lacustrine sediments near the base of sediment cores and overlying applied of the latter is radiocarbon dating, though numerous proglacial lacustrine and fluvial sediments are safe bets for workers have also used surface-exposure dating with cosmogenic minimum-limiting ages, but we must keep in mind the potential for radionuclides (CRN), and two papers report results of the applica- ice overriding, and not eroding, organic matter. tion of optically stimulated luminescence dating (OSL) to date Radiocarbon ages of organic material incorporated in till that a former ice position. underlies a moraine or in soil A-horizons buried by till (e.g., Ro¨th- Biological techniques are especially useful in dating moraines lisberger, 1987) provide maximum-limiting ages for moraine deposited during the last few centuries. The application of deposition. Organic matter in these stratigraphic settings is dendrochronology is limited to the southern Andes, where generally far less abundant than that in the aforementioned moraines are forested (e.g., Villalba, 1990; Villalba et al., 1990; Koch (minimum-limiting) setting. Maximum-limiting ages are most and Kilian, 2005). Lichenometry, which has been widely applied in commonly reported from the southern Andes where glaciers the Northern Hemisphere and New Zealand, has not been used advanced into forests or peat lands (e.g., Lowell et al., 1995). It is extensively in the Andes. The few lichenometric studies under- commonly assumed that the glacial advance killed the organic taken (Rodbell, 1992; Harrison and Winchester, 2000; Rabatel et al., matter that was dated and thus the radiocarbon age provides 2005; Solomina et al., 2007; Jomelli et al., 2008; in press)have a close maximum-limiting age for an ice advance, but only in the demonstrated the utility of the technique in the central and rare instances where minimum-limiting radiocarbon ages are southern Andes to date LIA and older moraines. available for the same moraine is this demonstrable. The bulk of the moraines summarized in this review have been Organic matter subjacent to outwash sand and gravel down- dated by radiocarbon analysis. It is important to note that this valley from moraines has been used in an attempt to provide technique can only provide limiting ages for moraines, and it is maximum-limiting ages for the upvalley moraines and/or glacial rarely possible to ascertain the degree to which a particular advances (e.g., Gonzalez et al., 1965; Mercer and Palacios, 1977; radiocarbon age underestimates or overestimates the true age of Helmens, 1988). However, because the stratigraphic relationship a moraine. Radiocarbon ages from organic matter in lakes and peat between the outwash deposits and the moraines is rarely exposed, lands upvalley from moraines provide only minimum-limiting ages it is seldom known whether the outwash correlates with the glacial for downvalley moraines. The stratigraphically basal-most organics advance that deposited the upvalley moraine in question, or at these sites provide the closest minimum-limiting age for whether the outwash correlates with another moraine that lies deglaciation from a downvalley moraine position providing that farther upvalley. It is also possible that the sand and gravel was not contamination and hard water issues are not a problem. However, associated with the deposition of any moraine but rather was in many cases basal-most organic sediments upvalley from deposited during a flood generated by the breaching of an upvalley moraines are underlain by decimeters to meters of inorganic glacial moraine (e.g., Fig. 4). These ‘‘aluviones’’ have been frequent and flour, sand and gravel, and it is difficult to accurately estimate the devastating in such tectonically active regions as the Cordillera rate at which these proglacial sediments were deposited. Further- Blanca, Peru (Lliboutry et al., 1977; Ames, written communication, more, it is possible that a significant interval of time passed 2000), and their distal deposits can be difficult to distinguish from between ice retreat and the attainment of conditions conducive to glacial outwash. Thus, radiocarbon ages from organic matter in peat growth, which are dependent on site-specific environmental these stratigraphic settings generally cannot provide an unambig- and hydrologic conditions (e.g., Marden and Clapperton, 1995; uous age for nearby moraines. Sugden et al., 2005). Thus, because an unknown interval of time elapsed between glacier recession from a coring locality and the start of organic sedimentation or peat growth at that locality, it is not possible to accurately estimate the temporal offset between a radiocarbon age and the time of either deglaciation or moraine deposition. It has been commonly asserted or implied that such radiocarbon ages provide close minimum-limiting age constraints for downvalley moraines, but only in the rare instances that maximum-limiting ages are also available can this relationship be demonstrated. Moraines that are dated by both maximum- and minimum-limiting ages are indeed rare, and one of the limitations of attempting to identify temporal patterns of glaciation in a region is the uncertainty of the temporal relationship between limiting radiocarbon ages and the age of moraine deposition. Recently published evidence suggests that we need to be somewhat more skeptical than we have been about whether or not the basal-most sediments upvalley from moraines can even be assumed to postdate glaciation and thus provide minimum- limiting age constraints for a glacial advance. The recent evidence comes from the west side of the Quelccaya Ice Cap (QIC) where Fig. 4. Laguna Jahuacocha (4076 m a.s.l.) on the west side of the northern end of the Thompson et al. (2006) dated numerous cushion plants (Distichia Cordillera Huayhuash, Peru (Fig. 1). The large alluvial fan (arrow) was deposited in AD 1932 during an outburst flood that resulted from the breaching of the upvalley muscoides), many in growth position, that have emerged from moraine. This event resulted in the rapid deposition of w50 cm of glacial flour in the beneath the rapidly-receding margin of the QIC. The average age of center of the lake. Lacustrine deposits from such events can be easily mistaken for the plants is w5.1 ka, and apparently the QIC advanced over the glacigenic outwash associated with an ice advance. Author's personal copy

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Some workers have attempted to date moraines by correlating date Lateglacial and Holocene moraines in the Andes have dated them with radiocarbon-dated paleobotanical or paleoecological between one and three boulders per moraine. Thus, in this paper evidence for cooler or wetter conditions, preserved in nearby we interpret CRN ages to provide minimum-limiting ages for the sediment cores or stratigraphic exposures (e.g., van der Hammen glacial advance in question. et al., 1981; Heusser and Rabassa, 1987). This approach assumes CRN ages are calculated using derived isotope production rates. that the glacier in question responded to the same climatic forcing, If the sample area is not at sea level and high latitude (SLHL), and with the same lag time, as did the particular fauna or flora. altitudinal and latitudinal scaling factors are needed to account for Because this relationship cannot be demonstrated, these ages differences in atmospheric density and geomagnetic shielding should also be viewed with skepticism and are not included in this (Gosse and Phillips, 2001). Several CRN scaling methods are in use review. (e.g., Lal, 1991; Stone, 2000; Lifton et al., 2005) and an unequivocal Numerous workers have applied CRN methods (reviewed in best choice has yet to emerge. At high latitudes, the choice of Gosse and Phillips, 2001) to date moraines deposited before and scaling method has little effect on the resulting ages, but at low during marine isotope (MIS) 2 in the Andes (e.g., Kaplan et al., 2004, latitudes the choice can make a difference of between w10% and 2005, 2008; Farber et al., 2005; McCulloch et al., 2005; Smith et al., 25%. Uncertainty in the SLHL production rate used in calculations, 2005a,b; Douglass et al., 2006; Zech et al., 2006, 2007; Ackert et al., however, affects ages from the Andes at all latitudes equally and is 2008), but relatively few workers (e.g., Douglass et al., 2005; Glasser independent of the scaling method used. The CRN ages cited in this et al., 2006) have used CRN methods to date Holocene moraines. CRN review are 10Be ages calculated using the scaling method of Lal methods are based on the formation and quasi-steady accumulation (1991) and Stone (2000) and are cited as published, with the over time of isotopes (e.g., 10Be, 26Al) in rocks exposed to cosmic rays. following exceptions. The published CRN ages of Smith et al. Boulders that are transported and eroded by glaciers, then deposited (2005a) for the Bolivian Andes were based on the scaling factors of on moraines, are assumed to have been ‘‘scraped clean’’ of previ- Lal (1991) and Stone (2000), but the ages presented here were ously-formed CRNs. Measuring the concentration of CRNs in the top recalculated using a revised geomagnetic correction subroutine surface of a boulder on a moraine is thus a means of determining (Farber et al., 2005) and are slightly younger than the published the amount of time since the boulder was deposited, and, under ages. The published ages of Zech et al. (2006, 2007) for the Bolivian ideal conditions, provides an age for the last moments of deposition and Chilean Andes were calculated using the scaling method of on the moraine. Geomorphologic processes such as boulder erosion Desilets and Zreda (2003) and Lifton et al. (2005), respectively. We and moraine degradation can, however, complicate this ideal have recalculated the Zech et al. (2006, 2007) ages using the relationship and must be considered site by site. CRONUS-Earth Online Calculator (henceforth, CRONUS Calculator; The interpretation of CRN ages from a single moraine requires http://hess.ess.washington.edu/math/index_dev.html; Balco et al., an understanding of the processes that can result in a range of ages. 2008) with the Lal (1991)/Stone (2000) time-dependent scaling Those boulders that have remained in a stable position on a mor- method for consistency and to facilitate comparisons between aine’s surface since deposition will yield ages that are closest to the regions. culmination of the ice advance. CRN ages from boulders that have One particularly challenging aspect of CRN dating in the Andes been post-depositionally exhumed or eroded, or that were depos- as applied to Early Holocene moraines is to distinguish the origin of ited by a post-glacial rockfall, will yield ages that underestimate the Holocene CRN ages; that is, whether the ages come from exhumed age of the moraine; similarly, boulders that have been buried by boulders on Lateglacial moraines or from boulders that have been snow for significant intervals will yield anomalously young CRN exposed since deposition on ‘‘truly’’ Holocene moraines (e.g., ages. Conversely, boulders previously exposed to CRNs prior to Douglass et al., 2005). This distinction is especially important for glacial entrainment and deposition, as would occur perhaps in the Middle and Early Holocene moraines as there is considerable doubt case of rockfall onto a glacier surface, will ‘‘inherit’’ CRNs and thus as to the veracity of many published radiocarbon ages on buried yield ages that predate the age of the advance. Shanahan and Zreda organics from the Andes that have been suggested to date (2000) and Putkonen and Swanson (2003) suggested that the episode(s) of glacial expansion during this interval (Porter, 2000). probability of inheritance may be as low as 3%; this is likely espe- We converted all radiocarbon ages to the calendar year time cially true where glaciers were warm-based (M.R. Kaplan, written scale using CALIB 5.0.1 using the INTCal04 calibration data set communication, 2008), a probable trait of most Andean (Stuiver and Reimer, 1993). In order to derive a single cal yr value paleoglaciers. with bounding error estimates (for plotting purposes) from the Workers have taken various approaches to interpreting pop- multiple intersection points that result from this calibration, we use ulations of CRN ages. Zech et al. (2006) interpreted the oldest age in the mean probability as calculated by CALIB 5.0.1 and calculate a population of CRN ages from a single moraine as being the closest errors to be the range (þ and ) from the mean probability that to the age of the advance, whereas all younger ages were taken to include all intersection points between a given radiocarbon age date the time of moraine stabilization, which may postdate the age with 1s analytical errors and the 14C yr-cal yr calibration curve. of the advance by centuries to millennia. Others have opted to identify age plateaus in a sequence of ages from a single moraine 4. Lateglacial and Holocene advances (e.g., Briner et al., 2002), and given sufficient CRN ages this approach should allow one to identify outliers both older and 4.1. Tierra del Fuego, southern Argentina and Chile younger than the true age of the moraine. Smith et al. (2005a) employed probability density curves on over 100 CRN ages from the Deglaciation from the maximum MIS 2 ice position (the Moat Peruvian and Bolivian Andes to distinguish populations of Glaciation) in the Beagle Channel (Tierra del Fuego, Fig. 2) began moraines, but relied primarily on older ages on moraines to esti- more than w17.7 ka (14.6 0.3 14C kyr BP; Table 1; Heusser, 1989). mate the timing of individual advances. These latter methods of Rabassa et al. (2000) envisioned a calving margin of the eastward- identifying outliers can be applied only if numerous CRN ages are flowing glacier that occupied the Beagle Channel, one that retrea- available for a given moraine, and Putkonen and Swanson (2003) ted rapidly westward toward the Cordillera Darwin. Midway suggests that at least six to seven ages are needed to ensure that through this first phase of deglaciation, moraines were deposited at one can distinguish outliers from ‘‘valid’’ ages for large moraines. Isla Gable and Pista de Ski; minimum ages for deglaciation from However, many workers who have employed the CRN method to these ice positions are w15 ka (12.7 0.1 14C kyr BP) and w14 ka Author's personal copy

Table 1 Chronological data for Late glacial moraines in the Andes.

a,b a,b a Country Region/ Approximate Approximate Radiocarbon CRN Luminescence Lab Notes Reference Locality latitude of longitude of number 1s Minimum- s 1s Maximum- 1s Maximum- s 1s Age s studies studies Minimum- þ1 þ1 (cal Age 1 limiting limiting (cal yr) (cal yr) limiting limiting (cal yr) (cal yr) (cal yr yr) (cal yr age age age age BP) BP) 14 14 ( C yr BP) (cal yr BP) ( C yr BP) (cal yr BP) Argentina Tierra del 53–55 S 66–74 W 10080 250 RL-2001 Minimum age Heusser and Fuego for Ushuaia Rabassa (1987) morainal complex minimum age for Ushuaia 10080 280 RL-1998 Morainal Heusser and complex Rabassa (1987) minimum age for deglaciation, Bahia 10920 70 UTC5402 Aguirre Rabassa et al., minimum age 2000 for ice retreat Rabassa et al., from Pista de 2000 Ski Moraine (late Moat Glaciation) 12060 60 13910 70 80 12100 50 13950 70 80 QL-4162 Minimum age Rabassa et al., for deglaciation 2000 in Ushuaia 12430 80 14480 180 260 Beta-55681 Minimum age Rabassa et al., for deglaciation 2000 in Ushuaia minimum age for deglaciation from the Isla 12730 90 15020 170 140 QL-1685 Gable moraine Heusser and (late Moat Rabassa (1987) Glaciation) 14640 260 17690 400 560 QL-4279- Minimum age Heusser, 1989 80 for deglaciation from maximum Moat ice extent S 69–71 W 10050 70 11580 170 180 A-8614 Minimum age McCulloch and Chile Straits of 53–55 for Stage E Bentley, 1998 Magellan/ (San Francisco) Bahı´a Inu´ til moraine limit minimum age for Stage E (San Francisco) moraine 10310 80 12130 220 150 AA-23077 limit weighted McCulloch mean age ( n¼8) et al., 2005 of Reclus tephra; maximum age for Stage E (San Francisco) moraine 12010 60 limit weighted McCulloch and mean age ( n¼2) Bentley, 1998 of Reclus tephra; maximum age for Stage E (San Francisco) moraine 12640 60 14910 140 150 limit Maximum McCulloch et al., age for Stage E 2005 (San Francisco) moraine 12720 60 15020 130 110 SRR-6501 limit Maximum McCulloch et al., age for Stage E 2005 (San Francisco) moraine Author's personal copy ) in in in in in McCulloch McCulloch McCulloch McCulloch Porter et al., 1992 in and Bentley, 1998 Porter et al., 1992 in and Bentley, 1998 McCulloch, 1994 in and Bentley, 1998 Clapperton et al., 1995 McCulloch et al., 2005 McCulloch et al., 2005 McCulloch et al., 2005 Clapperton et al., 1995 Mercer (1976) Clapperton et al., 1995 McCulloch et al., 2005 McCulloch et al., 2005 McCulloch et al., 2005 McCulloch et al., 2005 Porter, 1990 McCulloch and Bentley, 1998 Porter, 1990 McCulloch and Bentley, 1998 Clapperton et al., 1995 McCulloch and Bentley, 1998 Porter et al., 1992 in and Bentley, 1998 McCulloch et al., 2005 Clapperton et al., 1995 McCulloch and Bentley, 1998 Clapperton et al., 1995 McCulloch et al., 2005 McCulloch et al., 2005 continued on next page ( for Stage D moraine for Stage D moraine for Stage D moraine for Stage D moraine age for Stage E (San Francisco) Moraine limit Maximum age for Stage E (San Francisco) moraine age for deglaciation of Seno Minimum age for Stage D for Stage D moraine for Stage D moraine for Stage D moraine for Stage D moraine for Stage D moraine for Stage D moraine for Stage D moraine for Stage D moraine for Stage D moraine for Stage D moraine for Stage D moraine for Stage D moraine for Stage D moraine UtC-1635 Minimum age A-6362 Minimum age SRR-5143 Minimum age AA-12872 Minimum age A-7569Beta- 117943 limit Maximum SRR-6502 limit Minimum I-3512A-7569 Otway Moraine A-6791 Minimum age AA-30919 Minimum age SRR-6502 Minimum age AA-42415 Minimum age QL-1683 Minimum age QL-1470 Minimum age A-6807 Minimum age A-6357 Minimum age AA-42414 Minimum age A-6814 Minimum age A-7567AA-42416 Minimum age Minimum age AA-35082 Minimum age 13160 60 12740 120 15020 220 200 12820 100 0 0 1 3880 13160 60 13190 80 13610 90 12740 120 13720 260 12770 300 13590 200 13880 160 13890 50 13950 110 13050 100 13280 80 13430 310 13650 310 1385013850 80 90 1 12460 190 13400 140 Author's personal copy

Table 1 (continued )

10contaminated byBe lignite exposure Kaplan et al., 16000 1500 age from Stage 2008a D moraine, Bahıá Inu´ til 17170 1790 BI:C1 10 Be exposure McCulloch et al., age from Stage 2005 D moraine, Bahıá Inu´ til 17600 2880 BI:C2 10 Be exposure McCulloch et al., age from Stage 2005 D moraine, Bahıá Inu´ til 17700 2200 BI:C3 10 Be exposure McCulloch et al., age from Stage 2005 D moraine, Bahıá Inu´ til 10 18300 5300 Be exposure Kaplan et al., age from Stage 2008a D moraine, Bahıá Inu´ til 10 17500 1100 SM-02-07 Be exposure Kaplan et al., age from Stage 2008a D moraine, Strait of Magellan 10 17700 4200 SM-02-08 Be exposure Kaplan et al., age from Stage 2008a D moraine, Strait of Magellan Author's personal copy ) in Strelin and Marden and Clapperton, 1995 Marden and Clapperton, 1995 Marden and Clapperton, 1995 Kaplan et al., 2008a Kaplan et al., 2008a Fogwill and Kubik, 2005 Fogwill and Kubik, 2005 Fogwill and Kubik, 2005 Fogwill and Kubik, 2005 Ackert et al., 2008 Ackert et al., 2008 Ackert et al., 2008 Mercer, 1976 S. Stein (personal communication) in Malagnino, 2000 Strelin and Malagnino, 2000 Strelin and Malagnino, 2000 Marden and Clapperton, 1995 Stern (1990) Marden and Clapperton, 1995 Marden and Clapperton, 1995 Marden and Clapperton, 1995 Marden and Clapperton, 1995 continued on next page ( Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure for Advance F for Advance F for Advance F 10 10 10 10 10 10 10 10 10 age from youngest Stage D moraine, Strait of Magellan age from youngest Stage D moraine, Strait of Magellan age from Advance D moraine age from Advance D moraine age from Advance D moraine age from Advance D moraine age from Puerto Bandera II moraine age from Puerto Bandera I moraine age from Puerto Bandera II moraine for Puerto Bandera moraines Minimum age for Puerto Bandera moraines Maximum age for Puerto Bandera II moraine Maximum age for Puerto Bandera I moraine for Advance F Minimum age for Advance F for Advance E for Advance D for Advance D A-6805 Minimum age SRR-4582 Minimum age A-6354.1 Minimum age SM-02-01 PBS-04-19 SM-02-04 HT/3/99 HT/1/99 HT/4/99 PBN-04-15 I-2209 Minimum age INGEIS AC 1468 INGEIS AC 1469 PBS-04-05 A-6812 Minimum age A-6361QL-1475 Minimum age Minimum age A-6364HT/2/99 Minimum age 11300 2600 11300 1600 11900 1600 14500 1000 13400 1400 10500 1600 12400 1600 14800 1600 12900 1700 11100 730 12920 910 1080 13000 900 15370 1100 1340 12290 0 2 01 1 7 9180 120 10370 120 140 8150 50 9760 100 11160 110 290 8750 170 9820 300 270 8340 120 11250 90 13140 90 70 10390 10880 70 12870 30 40 10000 140 11550 200 290 W6 W 3 3 S7 S7 51.5 Paine National Park Chile Torres del Argentina Lago Argentina 49 Author's personal copy

Table 1 (continued )

a,b a,b a Country Region/ Approximate Approximate Radiocarbon CRN Luminescence Lab Notes Reference Locality latitude of longitude of number Minimum- 1s Minimum- þ1s 1s Maximum- 1s Maximum- þ1s 1s Age (cal Age 1s studies studies limiting limiting (cal yr) (cal yr) limiting limiting (cal yr) (cal yr) (cal yr yr) (cal yr age age age age BP) BP) 14 14 ( CyrBP) (cal yr BP) ( C yr BP) (cal yr BP) 9800 1400 PBS-04-30 10 Be exposure Ackert et al., age from Puerto 2008 Bandera I moraine 10500 1300 PBN-04-60 10 Be exposure Ackert et al., age from Puerto 2008 Bandera I moraine 11000 2600 PBN-04-61 10 Be exposure Ackert et al., age from Puerto 2008 Bandera I moraine 8500 2100 PBN-04-62 10 Be exposure Ackert et al., age from Puerto 2008 Bandera I moraine 12200 2200 PBN-04-66 10 Be exposure Ackert et al., age from Puerto 2008 Bandera I moraine 11900 2200 PBN-04-67 10 Be exposure Ackert et al., age from Puerto 2008 Bandera I moraine 13400 3400 PAT-98-001 36 Cl exposure Ackert et al., age from Puerto 2008 Bandera I moraine 11700 2000 PAT-98- 36 Cl exposure Ackert et al., 002 age from Puerto 2008 Bandera I moraine 36 9200 3800 PAT-98-050 Cl exposure Ackert et al., age from Puerto 2008 Bandera I moraine 36 9600 1800 PAT-98-051 Cl exposure Ackert et al., age from Puerto 2008 Bandera I moraine 10800 2000 PAT-98-100 36 Cl exposure Ackert et al., age from Puerto 2008 Bandera I moraine 11600 2800 PAT-98-101 36 Cl exposure Ackert et al., age from Puerto 2008 Bandera I moraine 11300 1600 PBS-04-05 10 Be exposure Ackert et al., age from Puerto 2008 Bandera II moraine 11300 2600 PBS-04-19 10 Be exposure Ackert et al., age from Puerto 2008 Bandera II moraine 8500 1400 PAT-98-057 36 Cl exposure Ackert et al., age from Puerto 2008 Bandera II moraine 10700 2400 PAT-98-054 36 Cl exposure Ackert et al., age from Brazo 2008 Rico moraine 12100 4600 PAT-98- 36 Cl exposure Ackert et al., 005 age from Brazo 2008 Rico moraine Author's personal copy ) Mercer, 1976 Mercer, 1976 Glasser et al., 2006 Glasser et al., 2006 Glasser et al., 2006 Glasser et al., 2006 Mercer, 1976 Mercer, 1982 Mercer, 1982 Mercer, 1982 Turner et al., 2005 Turner et al., 2005 Turner et al., 2005 Sylwan, 1989; Kaplan et al., 2004 Kaplan et al., 2004 Turner et al., 2005 continued on next page ( n n n n n ´ ´ ´ ´ ´ Be exposure Be exposure Be exposure 10 10 10 for deglaciation of west side of the SPIF to ‘‘modern’’ limits for deglaciation of west side of the SPIF to ‘‘modern’’ limits age for moraine in Rio Bayo Valley age for moraine in Rio Bayo Valley age for cirque moraine OSL age for ice contact sediments in Rio Bayo Valley for terminal Pleistocene deglaciation of eastern outlet of Lago Pueyrredo for terminal Pleistocene deglaciation of eastern outlet of Lago Pueyrredo for terminal Pleistocene deglaciation of eastern outlet of Lago Pueyrredo for terminal Pleistocene deglaciation of eastern outlet of Lago Pueyrredo for terminal Pleistocene deglaciation of eastern outlet of Lago Pueyrredo for deglaciation for deglaciation for Fenix I moraine, Lago Buenos Aires Minimum age for Fenix I moraine, Lago Buenos Aires for deglaciation LTE2 I-3507 Minimum age I-3825 Minimum age LTW1 LTE1 Aber79/ RN 1 GX-4168 Minimum age Beta-1404 Minimum age Beta-1237 Minimum age Beta-1236 Minimum age AA-42405 Minimum age AA-42409AA-35092 Minimum age St Minimum 10503 age Minimum age UZ-3921/ ETH-15654 AA-42408 Minimum age 9700 700 1140 0 90 0 10500 800 12500 900 13110 80 15510 170 200 12110 80 13960 80 100 11100 170 13030 110 140 11070 160 13010 100 130 11860 140 11850 80 11580 70 11660 195 11250 250 14620 150 12840 13012880 15160 160 200 15220 200 240 240 W W S 71–73 S74 46–48 48.75 mpano ´ Patagonia Iceﬁeld (SPIF) Te Chile North Chile Glaciar Author's personal copy

Table 1 (continued )

a,b a,b a Country Region/ Approximate Approximate Radiocarbon CRN Luminescence Lab Notes Reference Locality latitude of longitude of number Minimum- 1s Minimum- þ1s 1s Maximum- 1s Maximum- þ1s 1s Age (cal Age 1s studies studies limiting limiting (cal yr) (cal yr) limiting limiting (cal yr) (cal yr) (cal yr yr) (cal yr age age age age BP) BP) 14 14 ( CyrBP) (cal yr BP) ( C yr BP) (cal yr BP) 13550 100 16120 220 230 AA-35091 Minimum age Turner et al., for deglaciation 2005 14065 345 16840 530 570 St 10503 Minimum age Sylwan, 1989; for Fenix I Kaplan et al., moraine, Lago 2004 Buenos Aires 10540 1300 n/a Minimum age Turner et al., of kame delta 2005 12230 1500 n/a Minimum age Turner et al., of kame delta 2005 14400 900 Weighted mean Douglass et al., age for 2006 Menucos moraine 10 Be and 26Al 12800 3900 LBA-01-01 Kaplan et al., exposure age 2004 for Fenix I moraine, Lago Buenos Aires 10 15800 1700 LBA-01-06 Be and 26Al Kaplan et al., exposure age 2004 for Fenix I moraine, Lago Buenos Aires 10 16000 1600 LBA-01-05 Be and 26Al Kaplan et al., exposure age 2004 for Fenix I moraine, Lago Buenos Aires 15800 600 Weighted mean Douglass et al., age for Fenix I 2006 moraine 170 00 800 Weighted mean Douglass et al., age for Fenix II 2006 moraine Chile Lake District 41–42 S72–74W 13200 320 GX-4169 Maximum age Mercer, 1976 for Llanquihue III Advance 13300 550 GX-2954 Maximum age Mercer, 1976 for Llanquihue III Advance 13750 300 GX-4170 Maximum age Mercer, 1976 for Llanquihue III Advance 14820 230 I-5033 Maximum age Mercer, 1976 for Llanquihue III Advance 10820 900 I-1063 Minimum age Heusser, 1966 in for Llanquihue Porter, 1981 III Advance 12170 900 I-1062 Minimum age Heusser, 1966 in for Llanquihue Porter, 1981 III Advance 12200 400 GX-2935 Minimum age Mercer, 1976 for ﬁnal deglaciation of Lago Llanquihue 13900 120 TK-74 Maximum age Kobayashi et al., for Llanquihue 1974 in Porter, III Advance 1981 13970 240 UW-481 Maximum age Kobayashi et al., for Llanquihue 1974 in Porter, III Advance 1981 14200 140 UW-421 Maximum age Kobayashi et al., for Llanquihue 1974 in Porter, III Advance 1981 14250 400 GX-2948 Maximum age Heusser, 1974 in for Llanquihue Porter, 1981 III Advance Author's personal copy ) in Heusser, 1974 Porter, 1981 Lowell et al., 1995 Lowell et al., 1995 Lowell et al., 1995 Lowell et al., 1995 Lowell et al., 1995 Lowell et al., 1995 Lowell et al., 1995 Lowell et al., 1995 Lowell et al., 1995 Lowell et al., 1995 Lowell et al., 1995 Lowell et al., 1995 Lowell et al., 1995 Lowell et al., 1995 Denton et al., 1999 continued on next page ( of Llanquihue III advance from weighted mean of 5 wood and peat samples from beneath Llanquihue III outwash at Puerto Varas for Llanquihue III Advance of Llanquihue III advance from weighted mean of 35 wood and peat samples from beneath Llanquihue III outwash at Isla Grande de Chiloe of Llanquihue III advance from weighted mean of 8 wood samples from beneath Llanquihue III outwash at Lago Llanquihue for Llanquihue III Advance for Llanquihue III Advance for Llanquihue III Advance for Llanquihue III Advance for Llanquihue III Advance for Llanquihue III Advance for Llanquihue III Advance for Llanquihue III Advance for Llanquihue III Advance for Llanquihue III Advance for Llanquihue III Advance maximum- limiting age for youngest Llanquihue Advance Various Maximum age UW-479 Maximum age Various Maximum age Various Maximum age AA-13840 Minimum age Beta-10481 Minimum age GX-3809 Minimum age Beta-10485 Minimum age AA-13845 Minimum age AA-13844 Minimum age TUa-258A Minimum age A-8258 Minimum age T-10307A Minimum age AA-13842 Minimum age T-9662A Minimum age Numerous Close 17020 250 250 18020 440 240 18200 280 210 17600– 18220 14810 14240 14890 14490 120 14550– 14870 13160 100 13100 260 13370 100 13070 320 13350 110 13560 100 16130 220 230 13580 90 16160 210 220 13020 90 13940 270 16630 390 430 13040 210 13300 90 Author's personal copy

Table 1 (continued )

Bolivia Altiplano 19–20 S 66.5–67.5 W 13330 90 15820 200 220 A-7574 Maximum age Clapperton et al., for Advance 3 1997a 14020 100 16710 230 220 A-7572 Maximum age Clapperton et al., for Advance 3 1997a 12900– 15240– Not Range of 10 Clapperton, 1998 13400 16710 provided dates from peat-maximum age for Advance 3 10 Bolivia Cordillera 17.2 S 66.26 10900 700 RM-14 Be exposure Zech et al., 2007 Cochabamba 66.45 W age for younger recessional moraine, Rio Suturi 13300 800 RM-13 10 Be exposure Zech et al., 2007 age for younger recessional moraine, Rio Suturi Author's personal copy ) Lal/ Lal/ Lal/ Lal/ d d d d revised revised revised revised d d d d Zech et al., 2007 Zech et al., 2007 Zech et al., 2007 Zech et al., 2007 Zech et al., 2007 Zech et al., 2007 Zech et al., 2007 Zech et al., 2007 Zech et al., 2007 Zech et al., 2007 Zech et al., 2007 Zech et al., 2007 Smith et al., 2005a (CRONUS Smith et al., 2005a (CRONUS Smith et al., 2005a (CRONUS Smith et al., 2005a (CRONUS Stone time dependent) Stone time dependent) Stone time dependent) Stone time dependent) continued on next page ( Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 age for older recessional moraine, Rio Suturi age for older recessional moraine, Rio Suturi age for older recessional moraine, Rio Suturi age for recessional moraine, Huara Loma age for recessional moraine, Huara Loma age for recessional moraine, Huara Loma age for recessional moraine, Huara Loma age for younger recessional moraine age for younger recessional moraine age for older recessional moraine age for older recessional moraine age for older recessional moraine age for Moraine Group A, upper moraine age for Moraine Group A, upper moraine age for Moraine Group A, upper moraine age for Moraine Group A, upper moraine SF-23 ZONG-00- HH-11 RM-33 RM-31 HH-43 HH-22 HH-41 SF-51 SF-53 SF-52 ZONG-00- 05 ZONG-00- 04 ZONG-00- 01 RM-22 03 SF-21 11630 540 11630 600 15100 700 12130 490 11600 500 1100 0 500 10850 790 10700 800 10300 600 14600 600 12300 600 12600 60 12900 500 14000 800 13000 600 13000 500 W W 68.5 S 68.19 S 16.5 16.13 San Francisco Valley Zongo Valley Bolivia Cordillera Real/ Bolivia Cordillera Real/ Author's personal copy

Table 1 (continued )

a,b a,b a Country Region/ Approximate Approximate Radiocarbon CRN Luminescence Lab Notes Reference Locality latitude of longitude of number Minimum- 1s Minimum- þ1s 1s Maximum- 1s Maximum- þ1s 1s Age (cal Age 1s studies studies limiting limiting (cal yr) (cal yr) limiting limiting (cal yr) (cal yr) (cal yr yr) (cal yr age age age age BP) BP) 14 14 ( CyrBP) (cal yr BP) ( C yr BP) (cal yr BP) 12270 750 ZONG-00- 10 Be exposure Smith et al., 02 age for Moraine 2005adrevised Group A, upper (CRONUSd Lal/ moraine Stone time dependent) 10 12650 600 ZONG-00- Be exposure Smith et al., 11 age for Moraine 2005adrevised Group A, upper (CRONUSd Lal/ moraine Stone time dependent) 10 12810 440 ZONG-00- Be exposure Smith et al., 12 age for Moraine 2005adrevised Group A, upper (CRONUSd Lal/ moraine Stone time dependent) 10 16.13 S 68.20 W 13030 470 ZONG-00- Be exposure Smith et al., 09 age for Moraine 2005adrevised Group A, upper (CRONUSd Lal/ moraine Stone time dependent) 10 14240 500 ZONG-00- Be exposure Smith et al., 08 age for Moraine 2005adrevised Group A, upper (CRONUSd Lal/ moraine Stone time dependent) 10 14300 590 ZONG-00- Be exposure Smith et al., 10 age for Moraine 2005adrevised Group A, upper (CRONUSd Lal/ moraine Stone time dependent) 10 14390 660 ZONG-00- Be exposure Smith et al., 06 age for Moraine 2005adrevised Group A, upper (CRONUSd Lal/ moraine Stone time dependent) 10 15830 680 ZONG-00- Be exposure Smith et al., 07 age for Moraine 2005adrevised Group A, upper (CRONUSd Lal/ moraine Stone time dependent) 10 16.13 S 68.17 W 3420 200 ZONG-03- Be exposure Smith et al., 11 age for Moraine 2005adrevised Group B, upper (CRONUSd Lal/ moraine Stone time dependent) 10 5510 240 ZONG-03- Be exposure Smith et al., 08 age for Moraine 2005adrevised Group B, upper (CRONUSd Lal/ moraine Stone time dependent) 10 5940 220 ZONG-03- Be exposure Smith et al., 10 age for Moraine 2005adrevised Group B, upper (CRONUS -Lal/ moraine Stone time dependent) 10 7500 350 ZONG-03- Be exposure Smith et al., 04 age for Moraine 2005adrevised Group B, upper (CRONUSd Lal/ moraine Stone time dependent) 10 11030 330 ZONG-03- Be exposure Smith et al., 12 age for Moraine 2005adrevised Group B, upper (CRONUSd Lal/ moraine Stone time dependent) 10 12730 460 ZONG-03- Be exposure Smith et al., 03 age for Moraine 2005adrevised Group B, upper (CRONUSd Lal/ moraine Stone time dependent) Author's personal copy ) Lal/ Lal/ Lal/ Lal/ Lal/ Lal/ d d d d d d revised revised revised revised revised revised d d d d d d - - - - Seltzer, 1990 Seltzer, 1990 Lauer and Raﬁqpoor, 1986 Seltzer, 1990 Gouze et al., 1986 in Smith et al., 2005a (CRONUS Stone time dependent) Smith et al., 2005a (CRONUS Stone time dependent) Smith et al., 2005a (CRONUS Stone time dependent) Smith et al., 2005a (CRONUS Stone time dependent) Smith et al., 2005a (CRONUS Stone time dependent) Smith et al., 2005a (CRONUS Stone time dependent) Muller, 1985 Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Seltzer, 1992 Seltzer, 1992 Gouze et al., 1986 in Seltzer, 1992 Seltzer, 1992 Seltzer, 1992 Seltzer, 1992 Seltzer, 1992 Seltzer et al., 1995 continued on next page ( Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure 10 10 10 10 10 10 10 10 10 10 for late glacial moraines for late glacial moraines Minimum age for late glacial moraines age for Moraine Group B, upper moraine age for Moraine Group B, upper moraine age for Moraine Group B, upper moraine age for Moraine Group B, upper moraine age for Moraine Group B, upper moraine age for Moraine Group B, upper moraine Minimum age for late age for age for age for age for Minimum age for late glacial moraines Minimum age for late glacial moraines for late glacial moraines for Choqueyapu moraines for Choqueyapu moraines for Choqueyapu moraines for Choqueyapu moraines for Choqueyapu moraines Minimum age for Choqueyapu moraines MIL-00-16- SI-6997MS-80-15 Minimum age Minimum age ZONG-03- 01 MIL-00-17 ZONG-03- 05 ZONG-03- 09 T.520 Minimum age ZONG-03- 07 ZONG-03- 06 ZONG-03- 02 MIL-00-18 MIL-00-15 Beta-35048 Minimum age Beta-35069 Minimum age Beta-35050 Minimum age Beta-35068 Minimum age Beta-35071 Minimum age 9810 900 8230 900 9700 960 16120 480 17940 950 15280 660 15530 630 15920 1450 13660 550 14680 400 8160 160 9100 300 310 9720 120 9790 70 9920 80 11380 220 140 8090 170 9560 70 9980 90 10510 140 12460 260 270 10410 160 12300 340 240 10970 230 10790 60 12820 30 30 10460 140 12390 260 230 10020 120 W W W W 9 S 68.14 S 68.18 S 68.3 S6 16.17 16.14 15 Cordillera Real 16.32 Cordillera Real/ Palcoco Valley Apolobamba Bolivia Cordillera Author's personal copy

Table 1 (continued )

a,b a,b a Country Region/ Approximate Approximate Radiocarbon CRN Luminescence Lab Notes Reference Locality latitude of longitude of number studies studies Minimum- 1s Minimum- þ1s 1s Maximum- 1s Maximum- þ1s 1s Age (cal Age 1s limiting limiting (cal yr) (cal yr) limiting limiting (cal yr) (cal yr) (cal yr yr) (cal yr age age age age BP) BP) 14 14 ( CyrBP) (cal yr BP) ( C yr BP) (cal yr BP)

Peru Quelccaya Ice 14 S71 W 10910 160 12890 150 100 I-8209 Maximum age Mercer and Cap for Huancane II Palacios, 1977 moraine 11070 130 13010 90 110 DIC-686 Maximum age Mercer and for Huancane II Palacios, 1977 moraine 11190 190 13100 130 160 GX-4325 Maximum age Mercer and for Huancane II Palacios, 1977 moraine 12230 180 DIC-687 Maximum age Mercer and for Huancane II Palacios, 1977 moraine 9980 260 11570 460 390 DIC-685 Minimum-age Mercer and for Huancane II Palacios, 1977 moraines 10870 70 12860 30 40 AA-27032 Minimum-age Rodbell and for Huancane II Seltzer, 2000 moraines 11460 170 13330 140 190 I-8210 Minimum age Mercer and for Huancane III Palacios, 1977 moraine 12240 170 14210 270 330 I-8443 Minimum age Mercer and for Huancane III Palacios, 1977 moraine S 71.25 W 13880 150 16540 260 270 GX-23725 Maximum age Goodman et al., Peru Cordillera 13.75 for late glacial 2001 Vilcanota advance 13950 400 16680 590 650 GX-8081 Maximum age Mercer, 1984 for late glacial advance 14010 190 16710 300 320 I-9623 Maximum age Mercer, 1984 for late glacial advance 14500 110 Beta-1725 Maximum age Mercer, 1984 for late glacial advance 14830 450 GX-8189 Maximum age Mercer, 1984 for late glacial advance 10360 70 12230 150 150 AA-27041 Minimum age Goodman et al., for all late 2001 glacial moraines Peru Laguna Junin 10.75– 75.75– 10050 100 WIS-1068 Minimum age Wright, 1983 S W for deglaciation Plain/Western 11.25 76.5 Cordillera from the Punrun Glaciation; late glacial moraines are present downvalley from each of these dated localities 11950 150 13810 170 150 S-1489 Minimum age Wright, 1983 for deglaciation from the Punrun Glaciation; late glacial moraines are present downvalley from each of these dated localities Author's personal copy ) Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Wright, 1983 Wright, 1983 Wright, 1983 continued on next page ( Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure 10 10 10 10 10 10 10 10 10 age for Moraine Group B, lake damming moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, moraine from tributary valley age for Moraine Group B, moraine from tributary valley for deglaciation from the Punrun Glaciation; late glacial moraines are present downvalley from each of these dated localities Peat between two tills for deglaciation from the Punrun Glaciation; late glacial moraines are present downvalley from each of these dated localities 03 05 PE01-ALC- 06 PE01-ALC- 04 AL006 PE01-ALC- 25 WIS-1204 Minimum age AL010 PE01-ALC- 05 PE01-ALC- 07 WIS-1203 Minimum age 21310 620 15210 650 17730 450 27710 790 14750 520 PE02-ALC- 15750 540 PE01-ALC- 18460 470 15960 580 16340 530 12100 120 13540 130 16100 250 250 12800 130 15110 210 200 W W S 75.90 S 75.94 11.07 11.05 Laguna Junin Plain/Eastern Cordillera/ Alcacocha Valley Laguna Junin Plain/Eastern Cordillera/ Alcacocha Valley Author's personal copy

Table 1 (continued )

a,b a,b a Country Region/ Approximate Approximate Radiocarbon CRN Luminescence Lab Notes Reference Locality latitude of longitude of number Minimum- 1s Minimum- þ1s 1s Maximum- 1s Maximum- þ1s 1s Age (cal Age 1s studies studies limiting limiting (cal yr) (cal yr) limiting limiting (cal yr) (cal yr) (cal yr yr) (cal yr age age age age BP) BP) 14 14 ( C yr BP) (cal yr BP) ( C yr BP) (cal yr BP) 15260 870 PE01-ALC- 10 Be exposure Smith et al., 24 age for Moraine 2005a Group B, moraine from tributary valley 10 15370 650 PE01-ALC- Be exposure Smith et al., 23 age for Moraine 2005a Group B, moraine from tributary valley 10 15460 880 PE02-ALC- Be exposure Smith et al., 01 age for Moraine 2005a Group B, moraine from tributary valley 10 Laguna Junin 11.07 S 75.94 W 14750 520 PE02-ALC- Be exposure Smith et al., Plain/Eastern 05 age for Moraine 2005a Cordillera/ Group B, Alcacocha moraine from tributary valley Valley 10 15210 650 PE01-ALC- Be exposure Smith et al., 25 age for Moraine 2005a Group B, moraine from tributary valley 10 15260 870 PE01-ALC- Be exposure Smith et al., 24 age for Moraine 2005a Group B, moraine from tributary valley 10 15370 650 PE01-ALC- Be exposure Smith et al., 23 age for Moraine 2005a Group B, moraine from tributary valley 10 15460 880 PE02-ALC- Be exposure Smith et al., 01 age for Moraine 2005a Group B, moraine from tributary valley 10 Laguna Junin 11.07 S 75.93 W 12180 490 AL002 Be exposure Smith et al., Plain/Eastern age for Moraine 2005a Cordillera/ Group A, Alcacocha bedrock/ Valley ground moraine 10 13690 650 AL003 Be exposure Smith et al., age for Moraine 2005a Group A, ground moraine 10 13740 540 PE01-ALC- Be exposure Smith et al., 02 age for Moraine 2005a Group A, ground moraine 10 13750 520 AL001 Be exposure Smith et al., age for Moraine 2005a Group A, bedrock 16430 600 PE01-ALC- 10 Be exposure Smith et al., 01 age for Moraine 2005a Group A, bedrock 17770 620 AL005 10 Be exposure Smith et al., age for Moraine 2005a Group A, ground moraine Author's personal copy ) Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a Smith et al., 2005a continued on next page ( Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure Be exposure 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 age for Moraine Group A, ground moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, lake damming moraine age for Moraine Group B, nested lake-damming moraines age for Moraine Group B, nested lake-damming moraines age for Moraine Group B, nested lake-damming moraines age for Moraine Group B, nested lake-damming moraines age for Moraine Group B, nested lake-damming moraines age for Moraine Group B, nested lake-damming moraines age for Moraine Group B, nested lake-damming moraines AL004 PE01-ANT- 05 05 PE01-CAL- 04 PE01-CAL- 02 PE01-CAL- 03 PE01-ANT- 01 PE01-ANT- 03 PE01-CAL- 07 PE01-CAL- 06 PE01-ANT- 06 PE01-ANT- 07 PE01-ANT- 02 PE01-ANT- 04 PE01-CAL- 01 15140 720 17260 710 14570 600 15750 560 16730 510 13550 580 PE01-CAL- 14280 1320 15030 1720 14830 500 15060 470 16040 590 16690 470 14490 550 27890 480 18000 940 W W S 75.99 S 75.95 11.03 10.95 Laguna Junin Plain/Eastern Cordillera/ Antacocha Valley Laguna Junin Plain/Eastern Cordillera/ Calcacocha Valley Author's personal copy

Table 1 (continued )

a,b a,b a Country Region/ Approximate Approximate Radiocarbon CRN Luminescence Lab Notes Reference Locality latitude of longitude of number Minimum- 1s Minimum- þ1s 1s Maximum- 1s Maximum- þ1s 1s Age (cal Age 1s studies studies limiting limiting (cal yr) (cal yr) limiting limiting (cal yr) (cal yr) (cal yr yr) (cal yr age age age age BP) BP) 14 14 ( C yr BP) (cal yr BP) ( CyrBP) (cal yr BP) 10 Laguna Junin 10.96 S 76.00 W 15790 510 PE01-CAL- Be exposure Smith et al., Plain/Eastern 08 age for Moraine 2005a Cordillera/ Group B, lower Calcacocha moraine Valley 16420 650 PE01-CAL- 10 Be exposure Smith et al., 09 age for Moraine 2005a Group B, lower moraine 16970 600 PE01-CAL- 10 Be exposure Smith et al., 13 age for Moraine 2005a Group B, lower moraine 17500 610 PE01-CAL- 10 Be exposure Smith et al., 11 age for Moraine 2005a Group B, lower moraine 18090 640 PE01-CAL- 10 Be exposure Smith et al., 14 age for Moraine 2005a Group B, lower moraine 18320 620 PE01-CAL- 10 Be exposure Smith et al., 10 age for Moraine 2005a Group B, lower moraine 20180 1800 PE01-CAL- 10 Be exposure Smith et al., 12 age for Moraine 2005a Group B, lower moraine Peru Cordillera 10.5–10.75 S77 W 12500 340 14610 460 520 Minimum age Cardich et al., Raura for deglaciation 1977 Peru Cordillera 9.25–9.75 S77.3–77.5 W 10430 420 PE98RUC41 10 Be exposure Farber et al., Blanca age for Breque 2005 moraine 10650 370 PE98RUC42 10 Be exposure Farber et al., age for Breque 2005 moraine 10660 390 PE98RUC45 10 Be exposure Farber et al., age for Breque 2005 moraine 11340 530 HU-42 10 Be exposure Farber et al., age for Breque 2005 moraine 11800 290 HU-41 10 Be exposure Farber et al., age for Breque 2005 moraine 12590 450 PE98RU- 10 Be exposure Farber et al., 43b age for Breque 2005 moraine 12670 420 PE98RUC44 10 Be exposure Farber et al., age for Breque 2005 moraine 13160 460 PE98RU- 10 Be exposure Farber et al., 43a age for Breque 2005 moraine 10990 60 12930 40 60 GX-19558 Minimum age Rodbell and for Breque Seltzer, 2000 moraine 11280 110 13160 100 90 GX-17674 Maximum age Rodbell and for Breque Seltzer, 2000 moraine 13280 190 15750 290 320 GX-15850 Maximum age Rodbell and for Breque Seltzer, 2000 moraine Peru Cordillera 7.5–7.75 S77.5W 9700 270 GX-12853 Minimum age Birkeland et al., Oriental for late glacial 1989 moraines 10300 550 11950 820 640 GX-15851 Minimum age Rodbell, 1993a, for complete 1993b ﬁnal complete of Range Author's personal copy ) Heine, 1993 Clapperton and McEwan, 1985 Heine, 1993 Clapperton and McEwan, 1985 Heine and Heine, 1996 Heine and Heine, 1996 Heine and Heine, 1996 Heine and Heine, 1996 Heine and Heine, 1996 Heine and Heine, 1996 Heine and Heine, 1996 Clapperton et al., 1997b Clapperton et al., 1997b Birkeland et al., 1989 Birkeland et al., 1989 Rodbell et al., 2002 Rodbell et al., 2002 Heine and Heine, 1996 Heine and Heine, 1996 Heine and Heine, 1996 Heine and Heine, 1996 Rodbell et al., 1999 Rodbell et al., 2002 Rodbell et al., 2002 Rodbell et al., 2002 continued on next page ( ¼ 7) for Sucus ¼ 11) for n n for late glacial moraines for late glacial moraines for late glacial moraines for late glacial moraines for M4 moraine for M4 moraine for M4 moraine for M4 moraine for M6 and M5 moraines for M6 and M5 moraines Minimum age for M6 and M5 moraines Weighted mean minimum age ( moraines Weighted mean maximum age ( Potrerillos Advance for late glacial moraines for late glacial moraines Minimum age for late glacial moraines Minimum age for late glacial moraines Age of HL5 tephra; maximum age for M6 moraine Age of HL4 tephra; minimum age for M6 moraine for M5 moraine for M5 moraine Minimum age for late glacial moraines Minimum age for late glacial moraines Minimum age for late glacial moraines Minimum age for late glacial moraines HV-18066 Minimum age SRR-2581 Minimum age HV18077 Minimum age SRR-2582 Minimum age HV-17062 Minimum age HV-17529 Minimum age HV-18069 Minimum age HV-17069 Minimum age HV-17063 Maximum age HV-18068 Maximum age GX-16104 Minimum age GX-12852 Minimum age CAMS- 26409 CAMS- 26414 HV-17059 Minimum age HV-18076 Minimum age CAMS- 11967 CAMS- 26412 CAMS- 26411 CAMS- 34965 60 50 12860 12620– 13050 10510 80 12500 190 240 10850 100 12850 10860 10600– 11150 15450 1080–1011 11770 70 13160 80 15580 180 210 12100 190 14000 210 280 13070 60 15450 150 180 12080 610 14170 730 780 12220 60 14080 70 80 10800 60 10650 60 12720 80 50 10980 90 12930 60 80 11370 60 13240 50 50 12210 130 14110 150 260 12250 130 14180 230 250 12280 90 14190 170 190 7880 13070 8200– 90900 11160 100 13060 80 110 13010 100 15370 170 200 W 10210 60 W 10620 90 W .25W 12140 80 8 78.5 78.75 S 79–79.5 S7 S 0 2.5–3 1.5 Volcano National Park Carihuairazo Volcanoes Ecuador Pinchincha Ecuador Las Cajas Ecuador Papallacta Pass 0.25 Ecuador Chimborazo- Author's personal copy

Table 1 (continued )

Colombia High Plain of 4.25–4.75 N 74–74.25 12760 160 15030 280 270 GrN-14058 Minimum age Helmens, 1988 Bogota for moraine complex 4 12990 190 GrN-14052 Minimum age Helmens, 1988 for moraine complex 3 13210 170 15650 270 300 GrN-14422 Minimum age Helmens, 1988 for moraine complex 3 13710 80 16330 200 220 GrN-14061 Minimum age Helmens, 1988 for moraine complex 3 14660 280 17730 720 560 GrN-14060 Minimum age Helmens, 1988 for moraine complex 3 Colombia Cordillera 4.75–5 N 75.25– 12410 70 14440 170 230 GrN-10269 Minimum age Thouret et al., Central 75.5 W for Late Otun 1996 moraines 12430 70 14480 170 250 GrN-10265 Minimum age Thouret et al., for Late Otun 1996 moraines 12430 70 14480 170 250 GrN-9812 Minimum age Thouret et al., for Late Otun 1996 moraines 13000– 15360– Maximum age Thouret et al., 14000 16690 for Late Otun 1996 moraines

N71 W 10520 200 12420 350 250 Ta-2713 Maximum age Venezuela Sierra Nevada 8.25–9 Mahaney et al., for late glacial de Me´ rida 2008 advance 11440 100 13300 90 90 TO-9278a Maximum age Mahaney et al., for late glacial 2008 advance 11760 80 13610 110 110 TO-9011 Maximum age Mahaney et al., for late glacial 2008 advance 11850 180 TO-9278c Maximum age Mahaney et al., for late glacial 2008 advance a All radiocarbon and CRN ages and associated errors are rounded to nearest decade. b Ages in bold are the 3 oldest minimum-limiting ages and the 3 youngest maximum-limiting ages published for a given moraine; only the oldest and younges t of these, respectively, are used for Figs. 6–8 . Author's personal copy

D.T. Rodbell et al. / Quaternary Science Reviews 28 (2009) 2165–2212 2191

(12.1 0.1 14C kyr BP), respectively. However, the likely calving argued on the basis of seismic stratigraphy that the Puerto del nature of the ice margin during deglaciation raises the possibility Hambre site has been seismically displaced and thus the absence of that these moraines record an interval of grounded ice rather than lacustrine sediments at this locality does not necessarily require an a significant climatic reversal. Subsequent to the deposition of early deglaciation. More important, these apparently anomalously these moraines, the ice margin retreated farther west before old radiocarbon ages may reflect contamination by lignite (see pausing to deposit the Ushuaia morainal complex. Heusser and discussion in McCulloch et al., 2005) as numerous other minimum- Rabassa (1987) reported two minimum ages for the Ushuaia Drift of limiting radiocarbon ages range from w15.8 to 17.1 ka (13.3– w11.8 ka (10.1 0.3 14C kyr BP), and coupled with the aforemen- 14.3 14C kyr BP), and these have been suggested to provide a close tioned minimum age of w15 ka age for deglaciation from Isla de minimum-limit for the age of Advance D (McCulloch and Bentley, Gable they asserted that the Ushuaia Drift represented a Younger 1998; McCulloch et al., 2005). McCulloch et al. (2005) reported Dryas equivalent in the region. Fundamental to their assertion was three 10Be exposure ages from erratics on the surface of one of the correlation of the Ushuaia Drift with an interval of reduced inset right lateral moraines deposited during Advance D in Bahıá Nothofagus pollen in a well-dated core from Caleta Ro´ balo, w70 km Inu´ til; these range from 17.2 2.0 to 17.7 2.2 ka. Kaplan et al. east of Ushuaia. However, the Ushuaia Drift is now known to (2008a) confirmed these ages with two additional ages from this predate w14.5 ka (12.4 0.1 14C kyr BP) based on basal bog ages same moraine and calculated the resultant average of all five ages of from Ushuaia (Rabassa et al., 2000). Thus, it appears that all Late- 17.3 0.8 ka. Additionally, the oldest D moraine in the Strait of glacial ice positions in Tierra del Fuego predate w14.5 ka, and in the Magellan yielded an average 10Be exposure age of 17.6 0.2 ka, and absence of maximum-limiting ages their true ages remain elusive. the youngest D moraine in the Strait of Magellan yielded an average Kuylenstierna et al. (1996) mapped Holocene moraines in the age of 13.7 1.1 ka (Kaplan et al., 2008a). Cordillera Darwin and concluded that the Bahia Pia glaciers The age of the subsequent advance (Advance E) has also been the advanced and retreated several times during the Late Holocene. subject of some disagreement, and hinges on the age of the Reclus Minimum-limiting radiocarbon ages from peat lands and expo- tephra and the stratigraphic relationship of the tephra with lacus- sures of lacustrine sediments indicate that an older Neoglacial trine sediments associated with Advance E. The advance was advance culminated before w3.3 ka (3.1 0.1 14C kyr BP) and recognized on the basis of paleoshorelines in the Strait that are a younger Neoglacial advance occurred before w2.7 ka presumed correlative with Advance E (Clapperton et al., 1995), and (2.6 0.1 14C kyr BP). Kuylenstierna and colleagues also docu- subsequently a prominent moraine limit (the San Francisco mented the stratigraphy of diamictons, laminated sediment, and moraine) was identified on Isla Dawson and correlated with peat, and interpreted these stratigraphic relationships in terms of Advance E (McCulloch and Bentley, 1998; Bentley et al., 2005). fluctuations in the margins of the Bahia Pia glaciers. While the Clapperton et al. (1995) reported that the lake sediments associated stratigraphy documented by Kuylenstierna et al. (1996) is reason- with Advance E underlie the Reclus tephra whereas McCulloch and ably well dated, it hinges entirely on the correct interpretation of Bentley (1998) assert that the lacustrine sediments overlie the diamicts as tills, and the interpretation that the stratigraphic tephra. Furthermore, these latter workers observed no occurrence changes noted necessarily record discrete glacial advances. In spite of the Reclus tephra inside the mapped limits of Advance E, whereas of the numerous glacial advances envisaged by these workers, only the Reclus tephra has been noted at numerous localities outside the a single moraine was documented in their study area. We interpret limit of Advance E. If the latter observations are correct, then their radiocarbon ages to be minimum-limiting radiocarbon ages Advance E must post-date the Reclus tephra. The age of the Reclus for two Neoglacial advances. tephra itself has been the focus of considerable chronostratigraphic In the nearby valley of Ema Glacier in the Cordillera Darwin, effort. Based on a weighted mean of eight radiocarbon ages, Strelin et al. (2008) mapped multiple moraine ridges and docu- McCulloch and Bentley (1998) concluded that the tephra is mented the stratigraphy of till, proglacial outwash and lacustrine w13.9 ka (12.0 0.1 14C kyr BP) whereas McCulloch et al. (2005) deposits, and organic interstadial deposits. Some of the till units concluded that the tephra is w14.8 ka (12.6 0.1 14C kyr BP). The contain tree trunks, and Strelin et al. (2008) obtained seven latter age may be a better estimate because the organic matter dated radiocarbon ages between w0.3 and 3.4 ka (0.3–3.1 14C kyr BP). was found immediately subjacent to the tephra. Minimum-limiting These ages are interpreted to provide close maximum-limiting ages ages of w11.5–12.1 ka (10.0–10.3 14C kyr BP; Table 1) for Advance E for Neoglacial advances (Table 2). are provided by basal peat just inside the Advance E limit on Isla Dawson (McCulloch et al., 2005). Thus, Advance E appears to be 4.2. Strait of Magellan, southern Chile well-dated to between 12.6 ka and 14.8 ka. Just to the north of the Strait of Magellan, on the eastern side of Low-gradient glaciers advanced north-northeastward from the the Gran Campo Nevado Ice Cap, Koch and Kilian, 2005 dated a six- Cordillera Darwin into the Strait of Magellan at least five times fold sequence of LIA moraines using dendrochronology; accord- during the last glacial cycle (Clapperton et al., 1995; McCulloch ingly, ice was in advanced positions at wAD 1628, 1872/75, 1886, et al., 2005; Kaplan et al., 2008a), and two of these advances 1902, 1912, 1941. One important conclusion of their work is the apparently occurred during the Lateglacial (McCulloch and Bentley, observation that the LIA represents the most extensive Holocene 1998). During the ultimate and penultimate of these five advances, advance in this region, which contrasts markedly with other ice reached positions that are respectively 150 km and 80 km from records from southern South America. modern ice limits in the Cordillera Darwin, and dammed deep proglacial lakes in the central part of the Strait. The age of lacustrine 4.3. Torres del Paine National Park, southern Chile sediments in the Strait thus provides important age constraints on ice margin positions. The age of the penultimate advance (termed Marden and Clapperton (1995) and Marden (1997) mapped the Advance D, Clapperton et al., 1995) has been the subject of some limits of eight glacial advances (A–H) in and around Torres del uncertainty. Minimum-limiting radiocarbon ages from a bog at Paine National Park. Advances G and H are believed to be Holocene, Puerto del Hambre, some 100 km south of the Advance D limit, and Advances D–F appear to be Lateglacial. Moraines from Advance range from w19.0 to 19.7 ka (15.8–16.6 14C kyr BP; Table 1) and D are blanketed by the Reclus tephra, and thus the advance must were initially suggested to indicate early and rapid deglaciation of pre-date the tephra, which Marden and Clapperton (1995) assign to the Strait (Porter et al., 1992). McCulloch and Bentley (1998) have 13.8 ka. However, if we accept the aforementioned revised age for Author's personal copy

Table 2 Chronological data for Holocene moraines in the Andes.

Country Region/Locality Approximate Approximate Radiocarbon a,b CRNa,b Luminescence a Biological dating methods (cal yr BP) a,b,c Historical Lab Notes Reference latitude of longitude of records number studies studies Minimum- 1s Minimum- þ1s 1s Maximum- 1s Maximum- þ1s 1s Age (cal Age 1 Dendro- Licheno- Licheno- (cal yr BP) limiting limiting (cal (cal limiting limiting (cal (cal (cal yr yr) (cal yr s chronologic metric metric age age yr) yr) age age yr) yr) BP) BP) Age Age Age 14 14 ( C yr BP) (cal yr BP) ( C yr BP) (cal yr BP) Chile Cordillera 54 s70w 1790 80 1720 100 100 Ua- Minimum age for Kuylenstierna Darwin 4889 a younger et al., 1996 Neoglacial moraine minimum age for a younger 1950 80 1900 100 90 Ua- Neoglacial moraine Kuylenstierna 4888 minimum age for et al., 1996 a younger 2610 80 2720 130 210 Ua- Neoglacial moraine Kuylenstierna 4887 minimum age for an et al., 1996 older 2010 70 1970 80 90 Ua- Neoglacial moraine Kuylenstierna 4890 minimum age for an et al., 1996 older 3060 60 3270 90 60 Ua- Neoglacial moraine Kuylenstierna 4266 close maximum et al., 1996 limiting age 250 70 300 140 300 Ua- For Neoglacial Strelin et al., 13424 advance close 2008 maximum limiting age 340 70 390 70 80 Ua- For Neoglacial Strelin et al., 13420 advance maximum 2008 limiting age for 380 80 420 90 100 Ua- Neoglacial advance Strelin et al., 13419 maximum limiting 2008 age for 700 100 650 70 100 Ua- Neoglacial advance Strelin et al., 13425 close maximum 2008 limiting age 1290 80 1210 90 70 Ua- For Neoglacial Strelin et al., 13422 advance maximum 2008 limiting age for 1330 70 1250 60 70 Ua- Neoglacial advance Strelin et al., 13423 maximum limiting 2008 age for S 72.93 W 3140 80 3360 90 90 9 Ua- EcesisNeoglacial time advance¼15 KochStrelin and et al.,Kilian, 13421 years 20052008 Gran Campo 53 38 Ecesis time ¼15 Koch and Kilian, Nevado years 2005 48 Ecesis time ¼15 Koch and Kilian, years 2005 64 Ecesis time ¼15 Koch and Kilian, years 2005 77 Ecesis time ¼15 Koch and Kilian, years 2005 322 Ecesis time ¼15 Koch and Kilian, years 2005 Torres del Paine 51.5 S73W <60 Advance H; ecesis Marden and National Park time¼100 years Clapperton, 1995 105 Advance H; ecesis Marden and time¼100 years Clapperton, 1995 145 Advance H; ecesis Marden and time¼100 years Clapperton, 1995 225 Advance H; ecesis Marden and time¼100 years Clapperton, 1995 290 Advance H; ecesis Marden and time¼100 years Clapperton, 1995 S 73.25 W 1330 80 1240 80 70 Minimum age of Aniya, 1995 East side SPIF/ 51.25 Neoglaciation II Tyndall Glacier 3630 100 3950 190 120 HU-640 Minimum age of Aniya, 1995 Neoglaciation I 290 380 NU-637 Maximum age of Aniya, 1995 Little Ice Age close maximum age of 1370 80 1290 70 110 NU-356 Neoglaciation III Aniya, 1995 East side SPIF/ 50.03 S 73.3 W 1270 120 2850 150 120 GX- Minimum age for Mercer, 1976 Upsala Glacier 4162 Neoglacial maximum minimum age for Neoglacial 1425 130 1340 170 160 GX- Maximum Mercer, 1976 4163 minimum age for Neoglacial Author's personal copy ) Aniya, 1995 Aniya, 1995 Aniya, 1995 Mercer, 1965 Aniya, 1996 Aniya, 1995 Aniya, 1995 Mercer, 1976 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Mercer, 1965 Aniya, 1995 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 Masiokas et al., 2008 continued on next page ( close maximum age of Little maximum age for moraine outermost Neoglacial moraine close maximum age of Little maximum age of Neoglaciation a Little Ice Age moraine close maximum age of Little Minimum age for moraine minimum age of Neoglaciation minimum age of Neoglaciation NU-355 Ice Age moraine NU-657 Ice Age moraine NU-635 III (Pearson I) 1–988 6 km inside NU-658 Ice Age moraine NU-629 II (Hermanita) NU-659 Maximum age for GX- 4164 1–985 Maximum NU-630 II (Hermanita) 10 70 50 60 20 20 30 50 80 310 130 150 190 140 130 220 290 320 360 250 280 320 340 220 220 330 200 300 400 400 L 90 110 90 100 90 80 310 190 140 80 120 180 80 760 80 510 90 1520 80 420 80 380 120 2340 820 380 320 480 2310 1620 90 2430 270 220 2180 130 2180 160 170 3470 130 3750 150 180 2360 2000 100 1960 150 130 W W W W W 73.25 73.25 S 73.02 S 72.92 S 72.97 S S 50.6 50.5 49.32 49.27 49.08 East side SPIF/ Frias Glacier East side SPIF/ Ameghino Glacier East side SPIF/ Torre Glacier East side SPIF/ Piedras Blancas East side SPIF/ Lago del Desierto III Author's personal copy

Table 2 (continued )

Country Region/Locality Approximate Approximate Radiocarbon a,b CRNa,b Luminescence a Biological dating methods (cal yr BP) a,b,c Historical Lab Notes Reference latitude of longitude of records number Minimum- 1s Minimum- þ1s 1s Maximum- 1s Maximum- þ1s 1s Age (cal Age Dendro- Licheno- Licheno- studies studies 1 (cal yr BP) limiting limiting (cal (cal limiting limiting (cal (cal (cal yr yr) (cal yr s chronologic metric metric age age yr) yr) age age yr) yr) BP) BP) Age Age Age 14 14 ( C yr BP) (cal yr BP) ( C yr BP) (cal yr BP) L Chile East side SPIF/ 49.07 S 72.90 W 10 Masiokas et al., Lago del Desierto 2008 II 10 Masiokas et al., 2008 50 Masiokas et al., 2008 210 Masiokas et al., 2008 290 Masiokas et al., 2008 340 Masiokas et al., 2008 East side SPIF/ 49.05 S 72.90 W 50 Masiokas et al., Lago del Desierto 2008 I 50 Masiokas et al., 2008 120 Masiokas et al., 2008 210 Masiokas et al., 2008 320 Masiokas et al., 2008 East side SPIF/ 48.48 S 72.33 W 4320 110 4920 340 270 100 1–2204 Minimum age for Mercer, 1968 Narvaez Glacier moraine 250 ‘‘middle 19th Mercer, 1982 century age’’ for moraine Late 17th to early Mercer, 1982 18th century East side SPIF/ 47.65 S 72.25 W 4590 115 5260 200 210 1–2208 Close maximum age Mercer, 1976 San Lorenzo Este for moraine Glacier West side SPIF/ 49.2 S74 W 21 Mercer, 1982 Bru¨ ggen (Pio XI) Glacier West side SPIF/ 48.87 S 74.22 W 110 Ecesis time estimate Mercer, 1982 Hammick to be 70 years Glacier 200 Ecesis time estimate Mercer, 1982 to be 70 years West side SPIF/ 48.75 S74 W 4120 110 4640 180 120 12 1–3508 Minimum age for Mercer, 1970 Tempano Glacier moraine 190 Mercer, 1982 Mercer, 1970 West side SPIF/ 48.43 S 74.92 W 3740 110 4110 170 180 1–3511 Minimum age for Mercer, 1970 Ofhidro Sur moraine inset into Glacier older moraine(below) 4060 110 4570 240 150 1–3510 Minimum age for Mercer, 1970 moraine West side SPIF/ 48.42 S 73.88 W 100 Ecesis time estimate Mercer, 1982 Ofhidro Norte to be 70 years Glacier 160 Ecesis time estimate Mercer, 1982 to be 70 years 190 Tree tilted during Mercer, 1970 advance West side SPIF/ 135 Ecesis time estimate Mercer, 1982 Bernardo Glacier to be 70 years 175 Ecesis time estimate Mercer, 1982 to be 70 years East side NPIF/ 47.27 S 73.22 W 5 Harrison and Glaciares Winchester, Colonia, 2000 Arenales, Arco 45 Harrison and Winchester, 2000 75 Harrison and Winchester, 2000 East side NPIF/ 47.17 S73.15W 15 Winchester Glaciar Nef et al., 2001 66 Winchester et al., 2001 87 Winchester et al., 2001 Chile East side NPIF/ 46.27 S 73.22 W 540 40 550 70 30 2480 130 Winchester Leon Glacier et al., 2001 East side NPIF/ 46.95 S 600 40 600 40 50 SRR- Close maximum age Glasser et al., Soler Glacier 6605 for ice advance 2002 73.12 W 610 60 600 50 50 SRR- Maximum age for Glasser et al., 6604 advance 2002 Author's personal copy ) Mercer, 1982 Mercer, 1982 Aniya and Naruse, 1999 Aniya and Naruse, 1999 Sweda, 1987 Sweda, 1987 Sweda, 1987 Sweda, 1987 Glasser et al., 2002 Glasser et al., 2002 Glasser et al., 2002 Glasser et al., 2002 Glasser et al., 2002 Glasser et al., 2002 Glasser et al., 2002 Glasser et al., 2002 Douglass et al., 2005 Douglass et al., 2005 Douglass et al., 2005 Douglass et al., 2005 Douglass et al., 2005 Heusser, 1964 Lawrence and Lawrence, 1959 in Heusser, 1960 Lawrence and Lawrence, 1959 in Douglass et al., 2005 Douglass et al., 2005 Douglass et al., 2005 Douglass et al., 2005 Douglass et al., 2005 Douglass et al., 2005 Douglass et al., 2005 Douglass et al., 2005 Douglass et al., 2005 Douglass et al., 2005 Douglass et al., 2005 continued on next page ( Be age for Be age for Be age for Be age for Be age for Be age for Be age for Be age for 10 10 10 10 10 10 10 10 Be age for boulder Be age for boulder Be age for boulder Be age for boulder Be age for boulder Maximum age for advance Maximum age for advance Close maximum age for ice advance Maximum age for advance Maximum age for advance Maximum age for advance Maximum age for advance Reworked wood in lake sediments Maximum age for a pre-LIA advance Fachinal moraine Maximum age for advance Fachinal moraine on inner Fachinal moraine on inner Fachinal moraine on inner on inner Fachinal moraine weighted mean of 6 of 7 boulders from the inner Fachinal moraine on outer Minimum age for Tempanos I moraine ice advance 10 10 10 10 10 boulder on inner Fachinal moraine boulder on inner Fachinal moraine boulder on inner Fachinal moraine boulder on outer boulder on outer Fachinal moraine boulder on outer Fachinal moraine boulder on outer Fachinal moraine 10 Be age for boulder on outer Fachinal moraine 10 Be age for boulder on outer Fachinal moraine 10 Be age for boulder on outer Fachinal moraine boulder on outer Fachinal moraine SRR- 6611 SRR- 6608 SRR- 6603 SRR- 6612 SRR- 6606 SRR- 6609 SRR- 6607 FAC- 02-18 SRR- 6610 FAC- 02-06B FAC- 02-16A FAC- 02-04 FAC- 02-12 FAC- 02-07A Y-738- 2 Y-737 Maximum age for FAC- 02-20 FAC- 02-10 FAC- 02-16B FAC- 02-05B FAC- 02-02 FAC- 02-08A FAC- 02-06A FAC- 02-08B FAC- 02-05A 5 9 35 55 95 68 L 5700 6300 7700 1600 7300 1500 3900 1300 5200 2000 6200 800 6300 1300 7500 1700 7800 2500 8800 2200 6600 1200 6600 2000 8000 1200 11100 2800 11100 2100 10300 1800 10400 2000 7070 60 60 20 40 60 50 30 40 50 20 110 130 210 190 190 5060 860 60 860 940 50 710 50 50 1230 60 700 50 680 760 730 960 960 780 220 1020 1300 3030 6850 200 7710 3740 400 4130 650 550 W W 4 72.22 S7 46.67 46.57 West side NPIF/ San Rafael Glacier East side NPIF/ Fachinal Author's personal copy

Table 2 (continued )

S71 w 270 80 320 140 320 I-9624 Maximum age for Mercer and Peru Quelccaya Ice 14 LIA moraine Palacios, 1977 Cap 910 100 830 90 90 I-8441 Maximum age for Mercer and LIA moraine Palacios, 1977 Cordillera 13.75 S 71.25 w 330 50 390 60 80 AA- Maximum age for Goodman et al., Vilcanota 27050 LIA moraine in 2001 Upisamayo Valley 460 130 480 150 160 GX- Maximum age for Mercer, 1984 4925 LIA moraine in Upisamayo Valley 550 160 550 80 30 AA- Maximum age for Goodman et al., 27051 LIA moraine in 2001 Upisamayo Valley 630 70 DIC- Maximum age for Mercer and 678 LIA moraine in Palacios, 1977 Upisamayo Valley 4450 50 5100 180 130 NSRL- Maximum age for Mark et al., 10485 possible mid 2002 Holocene moraine in Paccanta Valley Peru Nevado 540 110 560 100 60 Minimum age for Seltzer, 1987 Huaytapallana late Holocene moraine Author's personal copy

Cordillera Raura 1010 50 930 50 120 SRR- Minimum age for Clapperton, 994 late Holocene 1981 moraine 2380 40 2420 40 70 SRR- Minimum age for Clapperton, 995 late Holocene 1983 moraine Cordillera 440 190 440 210 140 Hv- Maximum age for Ro¨thlisberger, Blanca/Glaciar 8704 advance of 1987 Ocshapalca Ocshapalca Glacier 2000 60 1960 80 80 Hv- Maximum age for Ro¨thlisberger, 8705 advance of 1987 Ocshapalca Glacier 3470 220 3760 310 300 Hv- Maximum age for Ro¨thlisberger, 8706 advance of 1987 Ocshapalca Glacier 4110 70 4640 170 120 Hv- Maximum age for Ro¨thlisberger, 11276 advance of 1987 Ocshapalca Glacier 4680 440 5320 580 490 Hv- Maximum age for Ro¨thlisberger, 12042 advance of 1987 Ocshapalca Glacier 6580 910 7410 950 1000 Hv- Maximum age for Ro¨thlisberger, 12041 advance of 1987 Ocshapalca Glacier Cordillera 3560 100 3860 120 150 HV- Maximum age for Ro¨thlisberger, Blanca/ Glaciar 8707 advance of 1987 Tulparaju Tulparaju Glacier 1370 60 1290 50 100 HV- Maximum age for Ro¨thlisberger, 8708 advance of 1987 age for ¨ Tulparaju Glacier Rothlisberger, advance of Glaciar 1987 Cordillera 690 50 650 30 90 Hv- Maximum Huallcacocha Blanca/ Glaciar 8703 1220 50 1150 80 80 Hv- Maximum age for Huallcacocha Ro¨thlisberger, 8709 advance of Glaciar 1987 Huallcacocha 1330 80 1240 80 70 Hv- Maximum age for Ro¨thlisberger, 8710 advance of Glaciar 1987 Huallcacocha 1530 220 1460 250 270 Hv- Maximum age for Ro¨thlisberger, 12040 advance of Glaciar 1987 Huallcacocha S77.15 W 1170 60 1100 80 110 Maximum age for ¨ Cordillera 9.6 Rothlisberger, Blanca/ advance of 1987 Quilcayhuanca Quilcayhuanca Glacier Glacier Cordillera 9.0 - 77.33 - 120 50 Solomina et al., 2007 Blanca 9.83 S 77.67 W 295 65 Solomina et al., 2007 1550 775 Age range for late Rodbell, 1992 Holocene ‘‘Quilloc’’ moraines Cordillera 9.7 S77.3W 1580 170 1500 190 190 GX- Maximum age for Rodbell, 1992 Blanca/ 14354 Quilloc moraine in Quebrada Quebrada Quilloc Quilloc 7290 320 8120 280 330 GX- Minimum age for Rodbell, 1992 14598 Rı´o Negro moraine, Quebrada Quilloc

Ecuador El Altar 1.7 S 78.5 W 2170 50 2190 120 70 SRR- Minimum age for Clapperton, 2587 moraine 1986 a All radiocarbon and CRN ages and associated errors are rounded to nearest decade. b Ages in bold are the 3 oldest minimum-limiting ages and the 3 youngest maximum-limiting ages published for a given moraine; only the oldest and younges t of these, respectively, are used for Figs. 6–8 . c The midpoint of age ranges is given for some published dendrochronologic and lichenometric ages; in these cases the errors represent the full age rang e(from the midpoint). Author's personal copy

2200 D.T. Rodbell et al. / Quaternary Science Reviews 28 (2009) 2165–2212 the Reclus tephra of w14.8 ka (McCulloch et al., 2005), then clarity over the stratigraphic setting of the minimum-limiting ages Advance D must be older than 14.8 ka. This older age is consistent (with respect to the PB I and PB II moraines) cast some uncertainty with minimum-limiting radiocarbon ages from within the Advance over this chronology. D limit, the oldest of which is w13.1 ka. CRN ages for the Advance D Ackert et al. (2008) applied surface exposure dating using the moraine have been reported by Fogwill and Kubik (2005); CRN 10Be and 36Cl to the PB I and PB II moraines and to the nearby a weighted mean based on four ages (Table 1) of 13.2 1.0 ka Brazo Rico moraine mentioned above. A total of 18 CRN ages were appears to be consistent with all aforementioned minimum- reported from these three moraines. The weighted mean of all ages limiting ages, yet inconsistent with either the older (14.8 ka) or the is 10.8 0.5 ka; the three moraines are indistinguishable from one younger (13.8 ka) age for the Reclus tephra (Fogwill and Kubik, another based on CRN ages. Thus, the weighted mean CRN age 2005). These latter authors suggest that there may be more than appears to violate the above mentioned minimum-limiting radio- one Reclus tephra, and that the tephra that mantles moraines of carbon age (w11.6 ka) of Mercer (1968). However, if the CRN ages Advance D is younger than the Reclus tephra dated by McCulloch are taken as minimum-limiting ages for the moraine, then the CRN et al. (2005). If, however, one assumes that the CRN ages for the and radiocarbon ages are not inconsistent. Also, it is important to Advance D moraines are minimum-limiting ages for the advance, note that this radiocarbon age is strictly only relevant to the Brazo then the CRN ages, the age of the tephra, and the minimum-limiting Rico moraine; the PB moraines dated by Ackert et al. (2008) and radiocarbon ages could be accordant. Strelin and Malagnino (2000) in the Lago Argentino basin may The age of Advance E is somewhat less clear. Marden and indeed be slightly younger than the Brazo Rico moraine. Clapperton (1995) report a minimum-limiting radiocarbon age of Heusser (1960) and Mercer (1970, 1976, 1982) pioneered w11.2 ka (9.8 0.1 14C kyr BP) from inside the Advance D limit. research into the timing of Holocene glacier variations in southern Furthermore, these workers observed thick deposits of reworked South America and much of their work was conducted around the Reclus tephra in deltaic deposits believed to be outwash from the Patagonian Ice Fields. Based on numerous radiocarbon ages, Mercer Advance E glacier, and they concluded that the glacier must have (1982) concluded that there are three broad groups of Neoglacial been in an advanced position during the eruption of Volcań Reclus, moraines in the region; these date to w4.5–4.0 ka, 2.7–2.0 ka, and and that the tephra was reworked by supraglacial meltwater. within the last few centuries. On the east side of the SPIF, three However, it is plausible that the tephra was reworked and depos- minimum-limiting radiocarbon ages between w3.8 and 4.9 ka ited by nonglacial streams during a time when ice was not in an (3.5 0.1–4.3 0.1 14C kyr BP) for the oldest Neoglacial moraine advanced position. are bracketed by a single maximum-limiting age of w5.3 ka Advance F is the best dated of the three Lateglacial advances. (4.6 0.1 14C kyr BP). These ages indicate that at least one Neo- Marden and Clapperton (1995) observed that drift of this advance glacial advance or stillstand occurred during the Middle Holocene. contains reworked Reclus tephra, and thus the advance must have However, it is important to note that these four ages came from four occurred after the Reclus eruption. Basal organic material from different valleys; no single moraine was dated by both maximum- a bog inside the Advance F moraine loop near Lago Pehoe yielded and minimum-limiting ages. The age of the next younger Neo- a radiocarbon age of w10.4 ka (9.2 0.1 14C kyr BP; Stern, 1990), glacial moraine is constrained by minimum-limiting ages of and thus Advance F must have occurred between 10.4 and 14.8 ka. w2.4 ka (2.2 0.1 and 2.4 0.1 14C kyr BP; Aniya, 1995). Moraines Moraines G and H were deposited during the Holocene, but only of the youngest Neoglacial moraines are dated by maximum- the latter have been dated closely (Marden and Clapperton, 1995). limiting ages between 1.3 and 1.5 ka (1.4–1.6 14C kyr BP) and Dendrochronology of the Group H moraines suggests a five-fold between w760 and 380 cal yr BP (820 80–320 80 14C yr BP; sequence of LIA moraines: AD 1725, 1660, 1805, 1845, and post AD Aniya, 1995); the latter are corroborated by dendrochronologic age 1890 (Table 2). estimates of AD 1850 and AD 1700 (Mercer, 1982). These two groups of maximum-limiting ages led Clapperton and Sugden 4.4. East Side of the South Patagonian Ice Field (SPIF) (1988) and Aniya (1995, 1996) to modify Mercer’s tripartite division of Holocene moraines into a four-fold subdivision. East of the SPIF, along the shores of Lago Argentina, Strelin and Detailed mapping and dendrochronology of five glacier forefields Malagnino (2000) mapped the extent of the Puerto Bandera (PB) in the Monte Fitz Roy and Lago del Desierto area by Masiokas et al. moraines and dated peat from within two of these moraines. The (2008) revealed large LIA moraines that date to the late 1500s to older of two peat samples yielded a maximum-limiting radio- early 1600s. Inset into these LIA moraines are moraines that record carbon age of w15.4 ka (13.0 1.0 14C kyr BP) for the PB I moraine a near synchronous advance in the early 1700s, and all five glaciers whereas the younger of the two peat samples yielded a maximum- show evidence of three to five subsequent advances between the limiting radiocarbon age for the younger PB II moraine of w12.9 ka mid-1800s and early 1900s, and significant ice retreat thereafter. (11.1 0.1 14C kyr BP). A minimum-limiting age for the PB moraines is reported to be an unpublished age of w12.3 ka (10.4 14C kyr BP) from the work of John Mercer (S. Stine, personal communication in 4.5. West Side of the South Patagonian Ice Field Strelin and Malagnino, 2000). Unfortunately, no stratigraphic or geomorphic context for this 12.3 ka age is provided by Strelin and Mercer’s work (summarized in Mercer, 1976) documented the Malagnino (2000), nor are the analytical errors or lab number complete and rapid deglaciation of the Glaciar Te´ mpano, an outlet included. However, Mercer (1968, 1976) did report a radiocarbon glacier on the west side of the SPIF. Peat exposed by recent ice age of w11.6 ka (10.0 0.1 14C kyr BP) for basal peat within the retreat yielded ages of around w13 ka (11.1 ka 14C kyr BP; Table 1), limit of a purported PB-correlative moraine at the outlet of paleo- which thus indicate that the Lateglacial ice limit was at or within lake Lago Brazo Rico, which is in an adjacent drainage basin to that modern limits by this time. Based in part on these data, Mercer containing the PB moraines dated by Strelin and Malagnino (2000). (1976) asserted that ice retreat region-wide began as early as ca Thus, the PB I moraines were apparently deposited between 11.6 15.4 ka (w13 14C kyr BP), and that there were no Lateglacial read- and 15.4 ka (10 and 13 14C kyr BP) and the PB II moraines between vances. However, Clapperton (1993b) correctly noted that the 11.6 and 12.9 (10.0–11.1 14C kyr BP); these appear to be among the Glaciar Te´mpano was a calving tidewater glacier, and that once its best-dated Lateglacial moraines in the Andes. However, the large retreat began and it had retreated into fiords during the Lateglacial analytical uncertainty of the maximum-limiting ages and a lack of interval of rising sea level, it would not have been able to respond to Author's personal copy

D.T. Rodbell et al. / Quaternary Science Reviews 28 (2009) 2165–2212 2201 the modest climatic reversals that may have occurred during the ages range from 940 to 550 cal yr BP (1020 60 to Lateglacial. 540 40 14C yr BP); these provide maximum-limiting ages for the Relatively few Holocene moraines have been dated on the west ice advance, though presumably the ages from the rooted tree side of the SPIF. The only radiocarbon dating consists of three provide a close maximum age (Table 2). Based on these ages, minimum-limiting ages for the oldest Neoglacial advance of Glasser et al. (2002) concluded that the Soler Glacier advanced between 4.1 and 4.6 ka (3.7 0.1–4.1 0.1 14C kyr BP); two between AD 1222 and 1342, which is several centuries earlier than moraines deposited during the youngest Neoglacial advance were the LIA as recorded in most regions of the world. The advance dated by dendrochronology to AD 1750 and 1850 (Mercer, 1970, documented by Glasser et al. (2002) appears to be a separate 1982). advance from the LIA as documented elsewhere in southern South America. It is important to note that Aniya and Naruse (1999) 4.6. North Patagonian Ice Field (NPIF) reported a maximum-limiting age for an advance of the Soler Glacier of wAD 1740, which corresponds with the LIA time frame. CRN dating of Lateglacial advances or stillstands comes from the From just south of the Soler Glacier, Winchester et al. (2005) numerous moraines that impound Lago Buenos Aires (Kaplan et al., reported a single OSL age of 2.5 0.1 ka, which appears to provide 2004; Douglass et al., 2006). CRN ages indicate that the ice front a minimum-limiting age for an advance of Glaciar Leon. advanced or stabilized near the eastern edge of Lago Buenos Aires On the east side of the northern end of the NPIF, Douglass et al. on at least three occasions during the Lateglacial depositing the (2005) reported results of the first attempt in South America to Menucos, Fenix I and Fenix II moraines w14.4 0.9 ka, intensively date Early Holocene moraines using CRNs. This study 15.8 0.6 ka, and 17.0 0.8 ka, respectively (Douglass et al., 2006). highlights both the potential of CRNs to date Early Holocene Kaplan et al. (2004) and Turner et al. (2005) reported radiocarbon moraines and the difficulty that one can encounter when inter- ages from varves that are stratigraphically between the Menucos preting such ages. Douglass and co-workers (2005) mapped the and Fenix I moraines; these ages range from w15.5 to 16.8 ka; inner and outer Fachinal moraines; seven CRN ages from the inner (12.8 0.1–14.1 0.3 14C kyr BP). The oldest radiocarbon age moraine range from 3.9 1.3 to 10.3 2.0 ka, and 12 CRN ages (w16.8 ka), which is a minimum-limiting age for the Fenix I from the outer moraine range from 6.6 2.0 to 15.2 3.5 ka (Table advance, appears to be inconsistent with the aforementioned CRN 2). As noted above, because of the low probability of encountering ages for the Fenix I moraine of 15.8 0.6 ka (Douglass et al., 2006). rocks with inherited CRNs, many workers take the oldest age or Mercer, 1976 reported four radiocarbon ages from the eastern ages to be closest to the true age of the moraine. In this case side of the NPIF, near the former outlet of Lago Pueyrredo´ n. Mercer however, Douglass et al. (2005) asserted that a weighted mean of interpreted these ages, which range from 13.2 to 13.8 ka (11.3 0.3 6.2 0.8 ka, which excluded the oldest CRN age, provided an to 11.9 0.2 14C kyr BP), to date the time that the lake became free accurate age of the inner Fachinal moraine. Similarly, a weighted to drain west to the Pacific Ocean via Rıó Baker, without subsequent mean of 8.5 0.7 ka that excluded the three oldest CRN ages, was interruption by Lateglacial ice readvances of the NPIF. Turner et al. asserted to be an accurate age for the outer Fachnial moraine. These (2005) confirmed Mercer’s chronology in reporting an age of workers suggest that the excluded ages reflect CRN inheritance, and w13.8 ka (11.9 0.1 14C kyr BP) for initial peat accumulation and that the reason for such a high proportion of inherited boulders is westward drainage of Lago Pueyrredo´ n. that the glacial interval was short-lived, so there was little time to From the northern end of the NPIF, Glasser et al. (2006) reported ‘‘dilute’’ the initial batch of boulders with inherited CRNs with CRN and OSL ages for moraines near Lago Tranquilo in the Rio Bayo ‘‘fresh’’ previously unexposed boulders. If correct, then Douglass Valley. The CRN ages suggest that the paleoglacier that occupied and co-workers (2005) have strong evidence for an Early Holocene this valley advanced by at least w10.9 1.0 ka (mean of two CRN glacial advance in South America, and a significant revision of the ages, Table 1). The glacier remained in an advanced position and Holocene glacial chronology is in order. However, their intriguing generated kame deposits, one stratum of which yielded a single OSL scenario remains to be tested; one such test would be to core bogs age of 9.7 1.0 ka. These authors note that the analytical uncer- and wetlands inside the Fachinal moraines to provide minimum- tainty associated with these ages precludes close correlation with limiting radiocarbon ages from basal organics. If Douglass and specific Lateglacial climatic events. At face value, these ages suggest coworkers are correct, there should be no pre-Holocene organic the possibility of an ice advance at least 20 km downvalley from the matter in this setting. modern ice limit during the Early Holocene, which contrasts with the aforementioned ages of deglaciation from similar geomorphic 4.7. Chilean Lake District settings in the southern part of the NPIF and elsewhere in southernmost South America. The glacial geology of this region is perhaps the most thoroughly The oldest radiocarbon-dated Neoglacial advance of the NPIF studied in South America (e.g., Heusser, 1966; Mercer, 1976; Porter, was established by Heusser (1960, 1964). He obtained a maximum- 1981; Lowell et al., 1995; Denton, 1999). Denton (1999) provide limiting age for an advance of the San Rafael Glacier, which is on the a helpful review of the history of work in this area. On numerous west side of the NPIF, of w7.7 ka (6.9 0.2 14C kyr BP) and occasions during the Late Quaternary, ice flowed westward onto a minimum age of w4.1 ka (3.7 0.4 14C kyr BP). Very recent the coastal plain to form large piedmont lobes, the youngest of advances of the San Rafael Glacier were dated by dendrochronology which, the Llanquihue III advance, occurred during the Lateglacial to AD 1880 and AD 1960. Numerous others have applied dendro- according to the radiocarbon chronology summarized by Lowell chronology to recent moraines around the NPIF (Lawrence and et al. (1995). During this advance, one ice lobe advanced into Lago Lawrence, 1959; Mercer, 1970; 1976; 1982; Sweda, 1987; Harrison Llanquihue (Fig. 1) and deposited the youngest set of moraines that and Winchester, 2000; Winchester et al., 2001). Results generally wrap around the western edge of the lake. In total, about 60 corroborate one another, with advances or stillstands occurring late maximum-limiting radiocarbon ages from wood and peat indicate in the 19th century and during the first half of the 20th century that the youngest Llanquihue advance postdates w17.0 ka (reviewed by Harrison et al., 2007). (w14.2 14C kyr BP; Lowell et al., 1995; Table 1). Denton, 1999 On the east side of the NPIF, Glasser et al. (2002) documented reported dozens of additional radiocarbon ages for the youngest a Late Holocene moraine that is partly composed of lake sediments Llanquihue advance and concluded that it occurred shortly after and rooted trees plowed up by the advancing ice. Ten radiocarbon w17.6–18.2 ka (w14.6–14.9 14C kyr BP), somewhat earlier than the Author's personal copy

2202 D.T. Rodbell et al. / Quaternary Science Reviews 28 (2009) 2165–2212 chronology reported by Lowell et al. (1995). Rapid deglaciation to 15.9 ka (12.9–13.4 14C kyr BP; no lab numbers or analytical errors followed this advance; deglaciation from the youngest Llanquihue were included). Thus, the advance culminated after w15.1 ka ice limit was underway by 16.6 ka (13.9 14C kyr BP) based on at least (12.9 14C kyr BP); no minimum-limiting ages were reported. Heine 14 minimum-limiting ages (Lowell et al., 1995), and ice had (2000), however, disputed the glacial origin of the diamict that retreated deep into the Andes, within 10 km of modern glaciers, by buries the peat, and he advocated a mass wasting origin for this w14.4 ka (12.3 0.4 14C kyr BP; Denton, 1999). deposit thus calling into question the glacial chronologic relevance Late Holocene moraines on the slopes of Cerro Tronador have of the radiocarbon ages. been mapped and dated by radiocarbon and dendrochronology (Lawrence and Lawrence, 1959; Ro¨thlisberger, 1987; Villalba et al., 4.10. Cordillera Cochabamba, central Bolivia 1990). Results indicate that, in addition to numerous LIA moraines that date from AD 1330 through the 19th century, there appear to Zech et al. (2007) developed a two-fold composite Lateglacial be moraines from an older, more extensive glaciation that occurred stratigraphy in two valleys based on nine Lateglacial CRN ages during the 11th and 13th centuries. (ages discussed here were recalculated). In the Rio Suturi Valley, the older of the two Lateglacial moraines yielded CRN ages of 4.8. Central Chile and Argentina 10.7 0.8–14.0 0.8 ka, and the younger moraine yielded ages 10.9 0.7–13.3 0.8 ka. In the nearby Huari Loma drainage, Zech et al. (2006) reported CRN ages from the Encierro Valley in a single Lateglacial moraine yielded CRN ages of 12.6 northern Chile (29S). Ten ages came from Lateglacial moraines and 0.6–15.1 0.7 ka. suggest a two-fold Lateglacial sequence. The older of the two Lateglacial moraines yielded six 10Be ages of between 11.9 1.1 and 4.11. Cordillera Real and Cordillera Apolobamba, northern Bolivia 18.2 1.8 ka (Table 1; recalculated using Lal (1991)/Stone (2000) scaling), and this advance was the most extensive advance of the From the westward draining Palcoco and Milluni Valleys of the past ca 30 ka, which is in clear contrast to either the southern Cordillera Real, Seltzer (1992) reported minimum-limiting radio- Andes or the wet tropical Andes (discussed below). The younger carbon ages from moraine-dammed lakes and peat lands that range four ages (13.8 1.3–15.2 1.4 ka, recalculated; Table 1)are between 10.9 and 12.8 ka (9.6 0.1–10.8 0.1 14C kyr BP). From interpreted by Zech et al. (2006) to date a recessional moraine inset the Milluni Valley, Smith et al. (2005a) reported four CRN ages that into the limits of the former moraine, although there is no provide minimum-limiting age constraints for Lateglacial compelling reason why this moraine does not record an ice read- moraines; these ages range from 8.2 0.6 to 16.2 0.5 ka. Farther vance at this time. north, in the San Francisco Valley, Zech et al. (2007) reported two No Holocene moraines were noted in the Encierro Valley study, sets of Lateglacial moraines. The younger of the two sets yielded but to the southeast in the Mendoza Andes, Espizua (2005) mapped two CRN ages, 11.0 0.5 and 11.6 0.5 ka, and the older set yielded and radiocarbon-dated a four-fold Holocene moraine sequence in three CRN ages between 10.3 0.6 and 14.6 0.6 ka. In the Zongo the Azufre and Penõ´ n Valleys. Radiocarbon ages indicate that the Valley, on the eastern side of the range, (Muller, 1985;inSeltzer oldest Holocene moraines (the Los Banõs del Azufre and Penõ´ n et al., 1995) reported a minimum-limiting radiocarbon age for moraines) are w5.9 ka (5.2 0.1 14C kyr BP), which bolsters the Lateglacial moraines of w11.2 ka (9.8 0.1 14C kyr BP). In this valley notion of a region-wide Early Holocene glacial advance. However, it Smith et al. (2005a) mapped Lateglacial moraines as far as 14 km should be noted that these ages are minimum-limiting ages, and north of the peak of Nevado Huayna Potosı´; eight CRN ages from without maximum-limiting age constraints it is conceivable that the older Lateglacial moraines (Group B) range from 10.2 0.3 to these moraines were deposited during the Lateglacial, with the 17.8 0.9 ka, whereas 12 CRN ages from the youngest Lateglacial onset of peat growth delayed by arid conditions during the Early moraines (Group A) range from 10.4 0.7 to 16.1 0.7 ka (Smith Holocene aridity (e.g., McCulloch et al., 2000; Sugden et al., 2005). et al., 2005a). In the Cordillera Apolobamba, which is north of but The second oldest Holocene moraines pre-date w5.5 ka nearly contiguous with the Cordillera Real, radiocarbon ages (4.8 0.1 14C kyr BP), and the third oldest pre-date w3.3 ka between w9.0 and 12.5 ka (8.1 0.2–10.5 0.1 14C kyr BP; Table 1) (3.1 0.1 14C kyr BP). Moraines that appear to correlate with the LIA from lakes and peat lands inside at least two sets of Lateglacial have minimum-limiting ages of w400 and 440 cal yr BP (350 60 moraines provide minimum-limiting age constraints for Lateglacial and 400 60 14C yr BP, respectively). ice advances or stillstands (summarized in Seltzer, 1990). Holocene moraine studies in the Cordillera Real have docu- 4.9. Central Bolivian Altiplano mented Late Holocene, pre-LIA moraines, as well as LIA moraines. Seltzer (1992) reported minimum-limiting radiocarbon Clapperton et al. (1997a) and Clayton and Clapperton (1997) ages for the oldest Holocene moraines in the Rio Palcoco catchment mapped moraines on the three massifs in the vicinity of Lago Poopo of between w630 cal yr BP (670 80 14C yr BP) and w870 cal yr BP and Salar de Uyuni on the arid Altiplano of southern Bolivia. Five (970 60 14C yr BP), and Gouze et al. (1986) reported minimum distinct ice limits were recognized, of which the older three appear ages in the Hichu-Kkota Valley of between w200 and 530 cal yr BP to be pre-Holocene. No ages were obtained from Holocene drift or (220 50–500 80 14C yr BP). Seltzer noted the absence of from drift of the oldest and most extensive advance (Advance 1). evidence for Middle or Early Holocene moraines; Lateglacial Advance 2 produced outwash fans that grade to deltas that are high moraines were reported immediately downvalley from these dated above the modern lakes. Thus, at least during Advance 2, glaciation moraines. Thus, the most extensive Holocene glaciation in the appears to be linked with an interval during which precipitation Cordillera Real occurred just prior to the LIA, which contrasts was 50–100% higher than today (Clayton and Clapperton, 1997). markedly with the chronology of Holocene glaciation documented During Advance 3, the paleoglacier at Cerro Azanques advanced in southern South America and in some areas of the northern into a peat bog and deposited till and outwash over folded peat; the Andes. Rabatel et al. (2005) conducted a detailed lichenometric peat yielded maximum-limiting ages for Advance 3 from w15.9 to study of LIA moraines in the forefields of five glaciers that emanate 16.7 ka (13.3 0.1 to 14.0 0.1 14C kyr BP; Table 1; Clapperton from Nevado Charquini (5392 m a.s.l.). These workers concluded et al., 1997a). Clapperton (1998) referred to 10 other unpublished that the maximum LIA glacier extent was achieved during the radiocarbon ages from this same peat exposure that range from 15.1 second half of the 17th century, and this was followed by steady Author's personal copy

D.T. Rodbell et al. / Quaternary Science Reviews 28 (2009) 2165–2212 2203 glacial retreat, with the exception of several intervals (10–20 years advanced during the onset of the YD, but during most of the YD the duration) during the 18th and 19th centuries when ice fronts either QIC was retreating. It is important to note that the advance that stabilized or readvanced. generated the H2 moraine in question need not have been a major one. It is plausible that the ice front retreated from the H3 moraine 4.12. Quelccaya Ice Cap (QIC) and Cordillera Vilcanota, (Fig. 5) <1 km upvalley from the location of the present H2 moraine southern Peru before readvancing to generate the H2 moraine. Given the flat floor of the Huancane´ Valley at this location, the H2 readvance could Mercer and Palacios (1977) subdivided moraines on the NW have been generated by a snowline lowering of only a few tens of side of the QIC (Fig. 1) into three groups (Huancane´ 1–3; Fig. 5). meters. The oldest moraines, Huancane´ 3, are older than w14.2 ka In the nearby Cordillera Vilcanota, Mercer and Palacios (1977), (12.2 0.2 14C kyr BP; Table 1) based on peat exposed inside this Goodman et al. (2001), and Mark et al. (2002) mapped moraines on moraine loop. Four radiocarbon ages from peat buried by till of the the northwestern side of the range. In a stream gully through Huancane´ 2 advance range from w12.9 to 14.2 ka (10.9 0.2– a prominent left lateral moraine high above the relatively flat floor 12.2 0.2 14C kyr BP), and since each of these provides of the Upismayo Valley, Mercer discovered an extensive exposure of a maximum-limiting age for the advance, it can be concluded that peat underlying till. The oldest ages from the base of the peat are the Huancane´ 2 advance culminated at or after w12.9 ka. Mercer w30 ka, but peat proximal to the contact with the overlying till and Palacios (1977) asserted that a radiocarbon age of w13.3 ka yielded ages between w16.5 and 18.1 ka (13.9 0.2– 14 (11.5 0.2 14C kyr BP) from peat buried by 3 m of outwash w2km 14.8 0.5 C kyr BP; Table 1). The youngest of these ages provides downvalley from the Huancane´ 2 moraine could be used to date the the closest maximum-limiting age for the advance. A minimum- onset of the Huancane´ 2 advance. Given that this alluvial gravel limiting age for this moraine is w12.2 ka (10.4 0.1 14C kyr BP; cannot be physically traced to the Huancane´ 2 moraine, it is equally Goodman et al., 2001) from a bog core on the floor of the Upismayo plausible that the alluvial gravels that overlie the peat were derived Valley. Thus, the prominent Lateglacial moraine in the Upismayo from the retreating Huancane´ 3 ice front several centuries prior to Valley is dated to between w12.2 and 16.5 ka. the onset of the Huancane´ 2 advance. Because of the ambiguity The extent and timing of Holocene glaciation in the QIC/Vilca- regarding the significance of this age, we will not include it in this nota region has been documented by Mercer and Palacios (1977), review except as a minimum age for the Huancane´ 3 moraines. The Goodman et al. (2001), and Mark et al. (2002). Evidence for a Mid- Huancane´ 2 advance was apparently short-lived, as evidenced by Holocene ice advance comes from the Paccanta Valley on the basal organic matter from Laguna Pacococha (Fig. 5), which is northwestern side of the Vilcanota, where peat directly underlies dammed by the Huancane´ 2 moraine as mapped by Mercer and till; the age of the peat (w5.1 ka; 4.5 0.1 14C kyr BP) provides Palacios (1977); this organic matter yielded a radiocarbon age of a maximum age for an ice advance (Mark et al., 2002). In the nearby w12.9 ka (10.9 0.1 14C kyr BP; Rodbell and Seltzer, 2000). A Upismayo Valley, an apparent LIA moraine is younger than younger minimum-limiting radiocarbon age of 11.6 ka maximum-limiting ages that range from w390–830 cal yr BP 14 (10.0 0.3 14C kyr BP) from peat within 500 m of the modern ice (330 30–630 70 C yr BP). Similarly, on the west side of the front (ca. AD 1975) was reported by Mercer and Palacios (1977). QIC, the Huancane´ 1 moraine is younger than peat incorporated Thus, here, the closest bracketing radiocarbon ages are indistin- into till that ranges in age from w320–830 cal yr BP (270 80– 14 guishable from one another (at 1s). Given that these ages strati- 910 100 C yr BP). Beneath the aforementioned dated peats, graphically bound the same moraine (Fig. 5), it appears that the QIC which provide maximum-limiting age constraints for LIA moraines

Explanation

H1 moraine

H2 moraine

H3 moraine 11,190 13.90º lake ±190 minimum-limiting14C age for downvalley moraines Quelccaya 14 12,230 maximum-limiting C age ±180 Ice Cap for downvalley moraines 270 ±80 01234km 11,070 910 5645 m ±130 ±100 13.93º nca né 12,240 Río H ua ±170

11,460 ±170 5445 m 10,910 13.97º ±160 9980 Laguna Acconcancha ±260 11,350 ± 110 (NSRL 10872)

Laguna Paco Cocha 10,870 ± 70 14.00º S 70.90º W 70.87º 70.83º 70.80º 70.77º

Fig. 5. Map of moraines and location of radiocarbon-dated localities on the west side of the Quelccaya Ice Cap in southeastern Peru (after Mercer and Palacios, 1977). All radiocarbon ages are expressed in 14C yr BP, and all are from Mercer and Palacios (1977) except the ages from Laguna Paco Cocha (Rodbell and Seltzer, 2000) and Laguna Acconcancha (Goodman et al., 2001). Author's personal copy

2204 D.T. Rodbell et al. / Quaternary Science Reviews 28 (2009) 2165–2212 in both the QIC and the Vilcanota, is peat that dates to w1.5 and elevation of w3800 m a.s.l. (Rodbell, 1993a). The Cordillera Blanca w2.8 ka (1.6 0.1 and 2.7 0.1 14C kyr BP; QIC) and w3.0 ka Normal Fault flanks the entire western side of the range and offsets (2.8 0.1 14C kyr BP; Vilcanota)(Mercer and Palacios, 1977). These numerous moraines of the last glacial cycle. Faulting of the outlet of ages imply that at these times, glaciers in these regions were an w0.5 km2 lake basin near Hacienda Breque (w4000 m a.s.l.) at smaller than their LIA extents. As noted above, Thompson et al. least w10.6 ka resulted in the subsequent fluvial incision of the lake (2006) reported rooted cushion plants dated w5.1 ka emerging basin (Rodbell and Seltzer, 2000). Extensive exposures throughout from the receding QIC margin, which suggests that at this time too the lake basin reveal the stratigraphic relationship between a Late- the QIC was smaller than its modern extent. glacial moraine (the Breque moraine), proglacial outwash gravels that are traceable to the moraine, and stratigraphically subjacent 4.13. Lake Junin Plain, central Peru lake sediments (Rodbell and Seltzer, 2000). Radiocarbon ages from peat within these lake sediments reveal that the Breque moraine Lake Junin, which sits in an intermontane basin between the was deposited by a Lateglacial readvance into the lake that cross-cut eastern and western cordillera of central Peru, was dammed by older upvalley moraines after w13.2 ka (11.3 0.1 14C kyr BP). A glaciofluvial fans more than 40 ka (Hansen et al., 1984). On the basal bog sample from inside the Breque moraine loop yielded an northern end of the Junin Plain and along the eastern side of the age of w12.9 ka (11.0 0.1 14C kyr BP), thus providing a minimum- Cerros Cuchpanga, Wright (1983, 1984) mapped moraines that he limiting age for the advance. The w12.9–13.2 ka age for the Breque attributed to the last glacial maximum (the Punrun Glaciation); the moraine is supported by eight CRN (10Be) ages that range from oldest minimum-limiting radiocarbon age for these moraines is 10.4 0.4 to 13.2 0.5 ka (Farber et al., 2005). The Breque moraine w16.1 ka (13.5 0.1 ka 14C kyr BP). Wright (1984) also recognized is w10 km downvalley from and w1000 m lower than the modern evidence of a Lateglacial readvance of ice from Cerros Cuchpanga glacier, and it is w5 km upvalley and 200 m higher than moraines that postdates the retreat of Punrun ice from that region; he named that date to w19 ka (Farber et al., 2005). this advance the Taptapta Glaciation. The Taptapa readvance is The chronology of Holocene glaciation in the Cordillera Blanca is poorly dated as basal radiocarbon ages from lakes within the one of the best studied in the tropical Andes; lichenometric and Taptapa ice limit range from w11.6 to 16.1 (10.0 0.1– radiocarbon ages reveal one of the most temporally-detailed 13.5 0.1 14C kyr BP) and no maximum-limiting ages are available. chronologies in this region (Table 2). Ro¨thlisberger (1987) and Valleys on the western side of the eastern cordillera were Rodbell (1992) reported minimum-limiting radiocarbon ages for glaciated on numerous occasions during the Late Quaternary (Smith possible Early Holocene moraines of between 4.6 and 8.1 ka. et al., 2005a,b). Smith et al. (2005a) reported 42 CRN ages (10Be) Whether these moraines are truly Early Holocene and not the from Lateglacial moraines in three of the west-facing valleys (from S product of a Lateglacial stillstand or readvance will require brack- to N: Alcacocha, Antacocha, and Calcalcocha Valleys). In all of the eting maximum-limiting age constraints for these same moraines. valleys, Lateglacial moraines are located about midway down the A pre-LIA, Late Holocene advance is clearly documented by both valley length and impound a lake; much older moraines (typically radiocarbon and lichenometric dating. Rodbell (1992) reported >150 ka) extend beyond the mouths of the valleys onto the Junin a Late Holocene moraine composed almost entirely of peat, folded Plain. Late-glacial CRN ages for Alcacocha Valley, the longest of the into an anticline within 2 km of the modern ice front in Quebrada three valleys (w14 km), range from 15.0 0.3 ka to 21.3 0.6 ka Quilloc. The youngest peat yielded a maximum age for the advance (with one outlier, 27.7 0.8 ka) for the lake-damming moraine and of w1.5 ka (1.6 0.2 ka 14C kyr BP), which is similar to a maximum 14.7 0.5 ka to 15.5 0.9 ka for a moraine extending from a tribu- age w1.5 ka (1.5 0.2 14C kyr BP) for a buried soil in a Late Holo- tary valley. CRN ages for bedrock and ground moraine at the upper cene moraine of Glaciar Huallcacocha (Ro¨thlisberger, 1987). This end of Alcacocha Valley range from 12.2 0.5 ka to 17.8 0.6 ka, pre-LIA advance may be bracketed by a minimum-limiting radio- with one outlier (27.9 0.5 ka). CRN ages for Antacocha Valley carbon age of 1.3 ka (1.4 0.1 14C kyr BP), however, because these range from 14.8 0.5 ka to 17.3 0.7 ka. CRN ages for Calcalcocha three ages are from three different valleys, the true age of this Valley range from 15.8 0.5 ka to 20.2 1.8 ka on the lower Late- advance remains ambiguous. Other maximum-limiting ages from glacial moraine and from 13.6 0.6 ka to 17.8 0.9 ka on a set of buried soils range from w440 cal yr BP (440 190 14C yr BP) to nested, lake-damming moraines farther upvalley. w3.9 ka (3.6 0.1 14C kyr BP; Ro¨thlisberger, 1987). Rodbell (1992) developed a preliminary lichen growth curve for 4.14. Cordilleras Raura and Huayhuash, central Peru the Cordillera Blanca, and concluded that the oldest definitively Holocene moraines were deposited between 1.7 and 3.6 ka (3.4– Little detailed work on the glacial chronology of these ranges has 1.8 14C kyr BP). Solomina et al. (2007) improved the lichenometric been published; a single radiocarbon age of w14.6 ka growth curve for dating LIA moraines, and concluded that LIA (12.5 0.3 14C kyr BP) from peat inside Lateglacial moraines (Car- advances occurred between AD 1590 and 1720, and between AD dich et al.,1977) provides a minimum-limiting age for deglaciation of 1780 and 1880. the Cordillera Raura. Clapperton (1983) reported a single maximum- limiting radiocarbon age for a Late Holocene ice advance in the 4.16. Cordillera Oriental, northern Peru Cordillera Raura; peat incorporated into till yielded a radiocarbon age of 2.4 ka (2.4 0.05 14C kyr BP). Preliminary CRN and radiocarbon Birkeland et al. (1989) and Rodbell (1993b) reported minimum- results from the Cordillera Huayhuash indicate that Lateglacial limiting radiocarbon ages between w11.1 and 14.0 ka (9.7– moraines there cluster w10.1 and w15.4 ka (Hall et al., 2006). 12.1 14C kyr BP) for Lateglacial moraines in this range. A minimum- limiting age of 12.0 ka (10.3 14C kyr BP) indicates the highest 4.15. Cordillera Blanca, northern Peru summits in this range (w4200 m a.s.l.) have remained ice-free for the entire Holocene. The Cordillera Blanca extends for more than 225 km along the NW–SE trending Continental Divide in central Peru (Fig. 1). With 4.17. Las Cajas National Park, southern Ecuador >600 km2 of ice (Georges, 2004; Silverio and Jaquet, 2005), it is the most extensively glaciated mountain range in the tropics today This region, with maximum summit elevations of w4500 m (Kaser et al., 1990). During the LGM, glaciers terminated at an a.s.l., was home to an w400 km2 ice cap during the last glacial cycle. Author's personal copy

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The rolling plateau above 4000 m a.s.l. and the numerous deep occasions. Clapperton and colleagues relied on exposures of dia- outlet valleys to the east and west of the Continental Divide contain micts intercalated with tephra and peat. The older of the two hundreds of glacial lakes. Basal radiocarbon ages from the highest advances, the Sucus Advance, is older than a weighted mean (n ¼ 7) cirque lakes (4060 m a.s.l.) indicate that the last deglaciation was age of w15.5 ka (13.1 14C kyr BP). A diamict of a younger advance complete by 15.6 ka (13.2 0.1 14C kyr BP; Rodbell et al., 2002), and (Portrerillos Advance) is bracketed by weighted mean ages of at no time since were these cirques reoccupied by glaciers. The <12.9 ka (10.9 14C kyr BP; n ¼ 11) and >11.6 ka (10.0 14C kyr BP; numerous moraines located downvalley from these cirques must be n ¼ 5)(Clapperton et al., 1997b). The chronology of events reported older than w15.6 ka, but no maximum-limiting ages have been by Clapperton and colleagues hinges on the correct interpretation of obtained. the diamicts exposed at these localities as primary till and not soliflucted till from older moraines upslope of dated localities or 4.18. Chimborazo-Carihuairazo Massif, central Ecuador debris flow deposits, which can be especially difficult to distinguish from till. Furthermore, the chronology of Clapperton and colleagues A Lateglacial readvance of the Reschreiter Glacier on the north does not date specific moraines, which makes it difficult to resolve side of Nevado Chimborazo crossed the Mocha Valley, an inter- with the chronology put forth by Heine and Heine (1996). Regard- montane depression between the Chimborazo and Carihuairazo less of which chronology is correct here, the presence of a Lategla- volcanoes, and dammed a lake. The oldest peat found intercalated cial ice cap at 0.25S and 4300 m a.s.l. w12.5 ka is also difficult to with lacustrine sediments within the lake basin yielded reconcile with radiocarbon ages noted above from a similar eleva- a minimum-limiting radiocarbon age for this readvance of tion in Las Cajas National Park in southern Ecuador (2.5S). These w13.2 ka (11.4 0.1 14C kyr BP; Clapperton and McEwan, 1985). latter ages indicate that the Cajas Plateau (w3950–4250 m a.s.l.) This peat has also been interpreted to require intervals of lake became ice free more than 15.6 ka and remained so ever since. drainage and refilling before and after w13.2 ka, which, in turn, reflect a retreat and readvance of the Reschreiter Glacier (Clap- 4.20. Central to northern Colombia perton and McEwan, 1985). Similarly, a younger peat layer has been interpreted to indicate a glacier retreat before and readvance after Helmens (1988) reported four moraine stages on and around the w12.7 ka (10.7 0.1 14C kyr BP). While the w13.2 ka peat clearly is High Plains of Bogota´ ; radiocarbon ages indicate that the youngest a minimum-limiting age for a Lateglacial readvance, the interpre- two moraine stages (3 and 4) are Late-Glacial. Moraine stage 3 is tation of the peat layers as requiring ice margin fluctuations is not older than w15.3–17.7 ka (13.0 0.2–14.7 0.3 ka 14C kyr BP) as clear. Heine (1993) redated the peat layers documented by based on four minimum-limiting radiocarbon ages from basal Clapperton and McEwan (1985) and obtained similar ages (Table 1). peat behind the stage 3 ice limit. Similarly, moraine stage 4 is However, Heine (1993) questioned whether the peat layers indicate older than w15.0 ka (12.8 0.2 ka 14C kyr BP). Helmens (1988) fluctuations in the ice margin, and suggested that the peat may asserted that moraine stage 4 must be younger than w15.3 ka simply have grown during dry conditions when the lake level was (13.0 0.2 14C kyr BP) based on the age of basal organics in front of lowered, after the Reischrieter Glacier retreated from the moraine the stage 4 ice limit. However, as noted above, radiocarbon ages that dammed the basin. Rodbell and Seltzer (2000) also visited this from beyond the limit of a glacial advance can only yield maximum- site and noted that the connection between the peat layers and the limiting ages for the advance in question if the dated organics are ice margin is ambiguous. clearly stratigraphically subjacent to proglacial outwash that is The only radiocarbon age that provides a definitive time physically traceable to the moraine in question. Because the constraint for a Holocene moraine in Ecuador comes from El Altar, stratigraphic relationship between this date and the stage 4 just to the southeast of the Chimborazo-Carihuairazo site. There, moraines is not clear, we will not use this radiocarbon age except as Clapperton (1986) reported a radiocarbon age of w2.2 ka a minimum-limiting age for the downvalley (stage 3) moraines. (2.2 0.1 14C kyr BP) from the basal-most organic material on top To the west in the Cordillera Central, Thouret et al. (1996) of the distal part of a Late Holocene moraine. reported that the Late Otun moraines are older than w14.5 ka (12.4 0.1 14C kyr BP; Table 1) based on basal organic matter inside 4.19. Rucu Pichincha and Papallacta Pass, northern Ecuador the limit of that advance. A maximum age limit for the Late Otun advance is provided by the absence of Tephra Unit VI on the Late Heine and Heine (1996) mapped moraines on Rucu Pichincha, Otun moraine surface; this tephra is between 15.4 and 16.7 ka (13– an active volcano that borders the city of Quito, Ecuador. They used 14 14C kyr BP; Thouret et al., 1996), and thus the advance must a combination of tephrochronology and radiocarbon ages from postdate the tephra. peats that stratigraphically underlie till to delineate two Lateglacial moraines. Accordingly, the M5 moraine is older than w15.4 ka 4.21. Northwestern Venezuela (w13.0 0.1 14C kyr BP), and the M6 moraine must be younger than the HL5 tephra (12.6–13.1 ka; 10.6–11.2 14C kyr BP), which is Mahaney et al. (2008) documented a Lateglacial advance at two absent from the surface of this moraine. A minimum age for the M6 localities in the Sierra Nevada de Me´rida. At each locality Lateglacial moraine is provided by the w9.2–10.1 ka (8.2–9.0 14C kyr BP) HL4 readvances produced push moraines over the top of peat bogs. Four tephra, which is found on the surface of the M6 moraine. radiocarbon ages from buried peat at two sites range from w12.4 to About 50 km east-southeast of Rucu Pichincha, on the north- 13.7 ka (10.5 0.2–11.9 0.2 ka 14C kyr BP), thus providing ernmost slopes of Volcań Antisana, is Papallacta Pass. Here, Heine maximum-limiting ages for the advance. Whether this readvance and Heine (1996) reported minimum-limiting radiocarbon ages of occurred during the Lateglacial or during the Early Holocene will w14.0–14.2 ka (12.1 0.1–12.3 0.1 14C kyr BP) for deglaciation require minimum-limiting radiocarbon ages from locations inside from moraines that mark the maximum ice extent of MIS 2. They the limit of this readvance. also reported maximum-limiting ages of w12.5–12.9 ka (10.5 0.1- 10.9 0.1 14C kyr BP) from peat under till of a Lateglacial (M6) 5. Synthesis advance. Clapperton et al. (1997b) conducted a detailed study of the region, and concluded that a small ice cap occupied the Portrerillos Given the range of synoptic climatic parameters affecting Plateau, and discharged outlet glaciers across the Pass on two different regions of the Andes, and the different sensitivities of Author's personal copy

2206 D.T. Rodbell et al. / Quaternary Science Reviews 28 (2009) 2165–2212 glaciers in these regions to specific climatic parameters (Section well-dated Lateglacial moraines, it is indeed challenging to discern 2.4, above), it is unlikely that Andean glaciers have responded in chronologic patterns along the length of the Andes. lockstep with one another over the Lateglacial or Holocene, or Sugden et al. (2005) and (Kaplan et al., 2008a,b) suggested that during any other time interval for that matter. The suggestion made on millennial time scales the southernmost Andes have been by some (e.g., Clapperton and Sugden, 1988), based on admittedly affected principally by the southern westerlies and by the state of ‘‘tenuous data,’’ that there has been synchrony in the timing of the Southern Ocean, and that this region has followed an Antarctic glacier fluctuation throughout the Andes during the latter half of climatic ‘‘beat,’’ with early warming interrupted by the ACR (15.2– the Holocene must be viewed with skepticism. 12.2 ka). This pattern appears to be supported by the moraine chronology in the Magellan Strait (53–55S; Figs. 1 and 6), with bracketing ages of lake sediments apparently correlative with 5.1. Lateglacial chronology Advance E that overlap the timing of the ACR. Furthermore, not far to the north, in the Lago Argentina Basin (49S), the PB I and PB II Of the numerous Lateglacial moraines that have been dated in moraines have bounding radiocarbon ages that overlap with the the Andes, only ten are firmly dated by both minimum-limiting and ACR and YD, respectively, though recent CRN ages suggest that the maximum-limiting radiocarbon ages (circled in Fig. 6). Among PB advances occurred after both the ACR and YD. Whether the PB I these ten, only two have been dated by both bracketing radio- and PB II moraines reflect a melding of the influences of the ACR carbon ages and by CRN ages: the Puerto Bandera moraine of the and the YD on the region or whether these moraines postdate both Lago Argentino basin and the Breque moraine of the Cordillera the YD and the ACR will require additional minimum-limiting Blanca, Peru (Sections 4.4 and 4.15). The ages of many other radiocarbon ages from inside the PB ice limits. A Northern Hemi- moraines throughout the Andes are constrained only by minimum- sphere influence appears strong in the Llanquihue III moraine of the limiting radiocarbon ages; far fewer are constrained only by Chilean Lake District (41–42S). This moraine, which is perhaps the maximum-limiting radiocarbon ages (Fig. 6). Given this paucity of best-dated moraine in the Andes (e.g., Lowell et al., 1995; Denton,

Fig. 6. Distribution of ages for Lateglacial moraines in the Andes. Locations are arranged from south (left) to north (right). Within each column, we plot the ages that are associated with moraines of increasing relative age from left to right. For clarity of illustration, only the oldest minimum-limiting radiocarbon ages and the youngest maximum-limiting radiocarbon ages are plotted; we do not plot any ages that have been questioned by authors regarding accuracy. In addition, we plot the oldest CRN age for moraines as long as this age is accepted at face value by the authors; several CRN ages, which authors have suggested reﬂect CRN inheritance, are not included in this plot. In several cases, authors have calculated the average CRN age for a moraine, and in these cases we plot only this age. Only nine moraines (circled) are dated by bracketing radiocarbon ages, and only two moraines (the Puerto Bandera moraine of the Lago Argentino basin and the Breque moraine in the Cordillera Blanca, Peru) are dated by both bracketing radiocarbon and CRN ages. Author's personal copy

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1999), correlates broadly with the Heinrich 1 event of the North other proxy paleoclimatic records from the region must be rigor- Atlantic Ocean (Bond et al., 1993). ously considered along with the glacial record, and in collaboration From the Peruvian Altiplano northward, there is considerable with climatic modelers, before comprehensive inter- and intra- evidence for an ice advance at about the time of the onset of the YD, hemispheric climatic linkages can be demonstrated. and less evidence for an earlier (ACR-type) advance. The Huancane´ 2 moraine on the western side of the QIC (14S) and the Breque 5.2. Priorities for future work on the Lateglacial moraine in the Cordillera Blanca (9.5S) are tightly bound by bracketing radiocarbon ages. In both cases these moraines appear This review highlights the need for improved age control in to correspond closely with the onset of the YD, but in both cases many regions of the Andes. Of utmost importance is the need for this advance appears to have been short-lived, with ice retreat additional bracketing radiocarbon ages for moraines in all regions. dominating much of the YD interval (Fig. 6). Only the Sucus Generally, minimum-limiting radiocarbon ages are more readily Advance at Papallacta Pass (Clapperton et al., 1997b) in northern obtained than maximum-limiting ages, and thus one useful Ecuador (0.25S) truly brackets the YD. However, as noted above, strategy would be to obtain basal organic matter from lakes and Heine and Heine (1996) developed a rather different chronology for peat lands upvalley from moraines for which maximum-limiting this same region. The only moraine that appears to correlate with ages are already available. Examples of such localities are the Sierra the ACR event in the tropical Andes is the above-mentioned Nevada de Me´rida of Venezuela and the Bolivian Altiplano (Fig. 6). moraine in the Cordillera Vilcanota (13.75S); the age of this The application of CRN dating to these sites would also provide moraine broadly straddles the ACR, though additional age control is valuable bracketing age control, and ongoing advances in CRN needed to fully demonstrate this correlation. dating will likely make this method even more suitable for the While it is tempting to assume that correlative events reﬂect Lateglacial, where dating moraines with sub-millennial resolution a common cause, it is important to keep in mind the possibility that is essential. Finally, data from regions that have yet to be studied are the Lateglacial interval was affected by a signiﬁcant degree of critical if we are to gain a better understanding of the spatial and spatial variability, with glaciers readvancing in different regions of temporal pattern of glacial advances during the Lateglacial. Areas in the Andes in response to local, rather than global, forcings. This need of better representation in regional datasets include the arid review has focused exclusively on glacial chronologies; the myriad regions of northern Chile and Argentina, the southern Peruvian

Fig. 7. Distribution of ages for Holocene moraines in the Andes. Locations are arranged from south (left) to north (right). Within each column, we plot the ages that are associated with moraines of increasing relative age from left to right. For clarity of illustration, only the oldest minimum-limiting radiocarbon ages and the youngest maximum-limiting radiocarbon ages are plotted; we do not plot any ages that have been questioned by authors regarding accuracy. In addition, we plot the weighted mean CRN age for two moraines at Fachinal Chile, following Douglass et al. (2005). There are no Holocene moraines that are dated by both maximum- and minimum-limiting radiocarbon ages. Author's personal copy

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Andes between 11.5 and 13.5S, and the Andes of northern Peru and time, however it is possible that these ages are minimum ages for southern Ecuador between 3 and 9S. Lateglacial rather than Early Holocene advance(s). The CRN ages of Douglass et al. (2005) for the east side of the NPIF at 46.6Sare 5.3. Holocene advances especially intriguing. As noted above, if these ages are accepted at face value, the ages document Early and Mid-Holocene intervals of Holocene moraines in the Andes have been firmly dated only expanded ice cover that exceeded in aerial extent all subsequent south of the Equator (Fig. 7). The majority of Holocene moraine advances. One exception to the widespread evidence for possible studies have focused on the sequences in the Cordillera Darwin Early and Mid-Holocene advance(s) is in the presently glacierized (Tierra del Fuego), around the Patagonian Ice Fields (SPIF, NPIF), and mountain ranges that border the Altiplano of northern Bolivia and in the Cordillera Real (Bolivia) and Cordillera Blanca (Peru). southern Peru (e.g., Quelccaya Ice Cap, Peru, and Cordillera Real, The Early Holocene is an especially intriguing interval in the Bolivia; Fig. 7). In this area, there is no evidence for expanded ice Andes as there are numerous minimum-limiting radiocarbon ages cover that exceeded the maximum ice extent of the last millennium. and a handful of CRN ages that suggest that there was a significant Radiocarbon ages from many glaciated valleys document solid ice advance during this interval, possibly the most significant evidence for multiple ice advances that pre-date the LIA of the advance of the Holocene (Fig. 7). However, only the Middle to Early Northern Hemisphere (Fig. 7), though only one moraine is dated by Holocene moraine of the San Rafael Glacier on the west side of the both maximum- and minimum-limiting radiocarbon ages. The best NPIF is firmly dated by bracketing radiocarbon ages at between 4.6 evidence in southern South America comes from the east side of the and 8.7 ka (Heusser,1960,1964). Numerous minimum-limiting ages SPIF, where radiocarbon ages suggest multiple advances between from the southern Andes (>40S), from the Mendoza Andes 1.0 and 2.6 ka. There is far less evidence from either the west side (35.3S), from the Cordillera Vilcanota (13.8S), and from the of the SPIF, the NPIF, or the Altiplano region for moraines deposited Cordillera Blanca (9.2-9.8S) suggest expanded ice cover at this during this interval. Farther north in the Cordillera Raura (10.5S),

Fig. 8. Distribution of ages for moraines of the last millennium in the Andes. Locations are arranged from south (left) to north (right). Within each column, we plot the ages that are associated with moraines of increasing relative age from left to right. For clarity of illustration, only the oldest minimum-limiting radiocarbon ages and the youngest maximum- limiting radiocarbon ages are plotted; we do not plot any ages that have been questioned by authors regarding accuracy. Author's personal copy

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Cordillera Blanca (9.2–9.8S), and El Altar (Ecuador; 1.7S) meridional transect that includes a wide range of climatic and numerous radiocarbon ages and some lichenometric data provide glaciologic settings. There are temporal patterns emerging in the age control for moraines during this interval. chronology of glaciation as developed over the past decades from Moraines deposited during the last millennium are numerous, Tierra del Fuego (Argentina) to the Sierra Nevada de Me´rida and are dated by a combination of radiocarbon, lichenometry, and (Venezuela). The Lateglacial (w16.7–11.5 ka) was marked by dendrochronology (Fig. 8). Moraines deposited between w0.5 and multiple advances and/or stillstands in all regions studied. In the 1.0 ka have been documented on the east side of the NPIF, around southernmost Andes, the Lateglacial chronology appears to have Cerro Tronador (w41S), in the Cordillera Real, on the west side of a strong Antarctic signature with the best-dated moraines over- the QIC, and in the Cordillera Vilcanota, the Cordillera Raura, and lapping with the ACR. In spite of the well-documented correlation the Cordillera Blanca. These moraines are slightly more spatially between the Llanquihue III moraine at 41–42S and glaciologic and extensive than moraines that correlate with the LIA of the Northern oceanic events in the Northern Atlantic region w17 ka, glaciers in Hemisphere. the southernmost Andes do not appear to have significantly read- All presently glacierized mountain ranges contain multiple vanced during the YD climatic reversal; the best-dated records moraines deposited during the last 450 years, and these correlate suggest ice retreat dominated much of the YD interval. However, with the LIA as defined in the Northern Hemisphere (Grove, 1988). indirect evidence (e.g., Aritzegui et al., 1997) does suggest a climatic It is difficult to identify pan-Andean intervals within the LIA during perturbation during the YD interval. At the other end of the Andes, which glaciers advanced, given the dating resolution of the chro- from w0–9N a stronger YD connection may exist, but critical nologic approaches available; most regions reveal a nearly contin- stratigraphic and geochronologic work is required before a YD ice uous temporal distribution of moraines during the LIA (Fig. 8). advance can be fully demonstrated. In the central Andes of Peru, two well-dated moraines strongly suggest a significant ice read- 5.4. Priorities for future work on the Holocene vance at the onset of the YD, but here again, during much of the YD interval, ice was apparently retreating. The most obvious priority for understanding the temporal pattern The spatial–temporal pattern of Holocene glaciation features of Holocene glaciation in the Andes is to acquire data from regions tantalizing but incomplete evidence for an Early to Mid- that have yet to be studied in detail. The region from northern Peru to Holocene ice advance (s) in many regions except the arid Andes northern Venezuela is strikingly underrepresented in this review. surrounding the Bolivian Altiplano. In this latter region, the LIA or While many workers have observed the presence of Holocene a slightly older advance that occurred within the last millennium moraines in this region, very few ages have been published. was the most extensive advance of the Holocene. In many There is a pressing need to resolve the Early to Middle Holocene regions, there is strong evidence for Neoglacial advances in the glacial chronology in the Andes. The numerous limiting radio- interval between 1.0 and 2.5 ka. Moraines dating to the LIA are carbon ages and the handful of the CRN ages summarized here seen in all presently glacierized mountain ranges; most of these provide tantalizing, if not compelling, evidence for significant date to within the past 0.45 ka. In many regions, a more extensive glacier advances during the Early to Middle Holocene. Porter advance occurred several hundred years prior to the onset of (2000) reviewed the record of Middle Holocene ice advances the LIA. globally and concluded that a strong case for an early onset of Filling in the geographic gaps and resolving the specific Neoglaciation could not be made because of inadequacies in age chronologic problems noted in Section 4, through the increased control. Furthermore, he suggested that the few well-dated application of CRN dating along with the continued careful moraines were from glaciers with significant potential rockfall, or application of radiocarbon to provide bracketing ages for moraines, with snouts that extend into lakes, which could have driven these will vastly improve upon the present state of the moraine chro- glaciers to expand for non-climatic reasons. The Andean records nology of the Lateglacial and Holocene in the Andes. This improved summarized here and by Porter (2000) provide some of the best dating, in turn, will further elucidate spatial and temporal patterns provisional evidence globally for glaciation during the Early to of glaciation that cannot be resolved clearly with the present Middle Holocene. What is needed now is to firm up the chronology dataset. for many of these moraines. For example, the Early to Middle Holocene CRN-dated moraines of the NPIF (Douglass et al., 2005) need limiting radiocarbon ages to evaluate whether these moraines Acknowledgments were indeed deposited during the Holocene or instead during the Lateglacial. An equally advantageous approach would be to apply This manuscript is dedicated to the memory of Alcides Ames the CRN dating technique to 6–8 erratics on the few moraines for Ma´ rquez of Huaraz, Peru, who passed away on November 30, 2007. which maximum-limiting radiocarbon ages already exist (Fig. 7). Born in 1927 in the Quechua-speaking village of Chacas, Alcides Similarly, the numerous minimum-limiting ages and the few became Peru’s foremost glaciologist; he was instrumental in maximum-limiting ages need corresponding bracketing radio- monitoring the mass balance of glaciers in the Cordillera Blanca and carbon ages. Cordillera Ruara, Peru, and in documenting variations in ice fronts The apparent lack of moraines that pre-date the last millennium and the development of proglacial lakes in these ranges (e.g., Kaser in some ranges (e.g., Cordillera Real, Bolivia) needs to be evaluated. et al., 1990; Hastenrath and Ames, 1995; Ames and Hastenrath, If true, this lack of moraines would suggest that a broad regional 1996a,b; Ames, 1998). He also led a nationwide effort to inventory paleoclimatic condition, perhaps aridity, precluded glaciers in these every glacier in Peru (Ames et al., 1989). Perhaps equally important regions from advancing earlier. Likewise, the lack of evidence for to those of us who have worked in Peru is the degree to which moraines deposited between 0.5 and 1.0 ka in some regions, such as Alcides promoted international glaciological and glacial geological the SPIF, needs to be evaluated. research efforts in his beloved Cordillera Blanca. Countless foreign scientists and students have lodged at his family-run pensio´ n and 6. Conclusions benefited from his generosity and wisdom, which was rooted in decades of experience on the ground in every corner of the Range. The Andes offer an unparalleled opportunity to document the We are grateful to the thorough and helpful reviews of P.T. Davis, S. chronology of glaciation along a continuous 68-degree-long Harrison, and M.R. Kaplan. Author's personal copy

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