The Dominion Range Ice Core, Queen Maud Mountains, Antarctica - General Site and Core Characteristics with Implications

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Paul A. Mayewski University of Maine

Mark S. Twickler University of New Hampshire, Durham, [email protected]

W. Berry Lyons University of New Hampshire, Durham

Mary Jo Spencer University of New Hampshire, Durham

Debra A. Meese U.S. Army Cold Regions Research and Engineering Laboratory

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Recommended Citation Mayewski, P. A., Twickler, M. S., Lyons, W. B., Spencer, M. J., Meese, D. A., Gow, A. J., . . . Saltzman, E. (1990). The Dominion Range Ice Core, Queen Maud Mountains, Antarctica - General Site and Core Characteristics with Implications. Journal of Glaciology, 36(122), 11-16. doi:10.1017/ S0022143000005499

This Article is brought to you for free and open access by University of New Hampshire Scholars' Repository. It has been accepted for inclusion in Faculty Publications by an authorized administrator of University of New Hampshire Scholars' Repository. For more information, please contact [email protected]. Authors Paul A. Mayewski, Mark S. Twickler, W. Berry Lyons, Mary Jo Spencer, Debra A. Meese, Anthony J. Gow, Pieter M. Grootes, Todd Sowers, M. Scott Watson, and Eric Saltzman

This article is available at University of New Hampshire Scholars' Repository: https://scholars.unh.edu/faculty_pubs/ 375 loumal oJ Glaciology, Vol. 36, No. 122, 1990

THE DOMINION RANGE ICE CORE, QUEEN MAUD MOUNTAINS, ANTARCTICA - GENERAL SITE AND CORE CHARACTERISTICS WITH IMPLICATIONS

By PAUL A. MAYEWSKI, MARK S. TWICKLER, WM BERRY LYONS, MARY Jo SPENCER,

(Glacier Research Group, Institute for the Study of Earth, Oceans and Space (EOS), University of New Hampshire, Durham, New Hampshire 03824, U.S.A.)

DEBRA A. MEESE,

(Glacier Research Group, Institute for the Study of Earth, Oceans and Space (EOS), University of New Hampshire, Durham, New Hampshire 03824, U.S.A., and U .S. Army Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire 03755, U.S.A.)

ANTHONY J. Gow,

(U.S. Army Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire 03755, U.S.A.)

PIETER GROOTES,

(Quaternary Isotope Laboratory, University of Washington, Seatt1e, Washington 98195, U.S.A.)

TODD SOWERS,

(Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882, U .S.A.)

M. SCOTT WATSON,

(Polar Ice Coring Office, University of Nebraska, Lincoln, Nebraska 68558, U.S.A.)

and ERIC SALTZMAN

(Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, Florida 33149, U.S.A.)

ABSTRACT. The Transa ntarctic Mountains of East they could provide some of the most climatically sensi ti ve Antarctica prov id e a ne w milieu for retrieval of ice-core records available from Antarctica. Furthermore, unlike records. We report here on the initial findings from the those ice cores retrieved from the interior of Antarctica, first of these records, the Dominion Range ice-core record. there are terrestrial records from nearby sites that can be Sites s uch as the Do minion Range are val uable for the used for comparison (e.g. De nto n and others, 1971; Drewry, recover y of records detailing climate change, volcanic 1980; Stuiver and others, 1981; Mayewski and Goldthwait, activity, and changes in the chemistry of the atmosphere. 1985). The unique geographic location of this si te and a relatively The Dominion Range (Fig. I) is th e first in a series of low accumulation rate combine to provide a relatively long planned Transa ntarctic Mountains ice-core sites (Fig. I). The record of change for this potentially sensitive climatic Dominion Range is located a long the edge of the East region. As such, information concerning the s ite a nd general Antarctic ice sheet, approximate ly 500 km from the South core characteristics are p resented, including ice surface, ice Pole and 120 km from the Ross Ice Shelf, at the confluence thickness, bore-hol e temperature, mean annual net accumu of Beardmore and Mill Glaciers (Fig. 2). These glaciers, lation, crystal size , crystal fabric, oxygen- isotope composi along with several other outl et glaciers in th e Queen Maud tion , and examples of ice c hemistry and isotopic Mountains (sub-sector of the Transa ntarctic Mountains), composition of trapped gases. drain the Titan Dome area o f the East Antarctic ice sheet. Approximately half of the Dominion Range (Fig. 2) is ice free and the average elevation of the range is 2700 m. INTRODUCTION Between 20 November and 14 December 1984, a tent camp was operated in the Dominion Range. Due to logistic Localized accumulation basins in the Transantarctic restraints, all aspects of the stud y, including reconnaissance, Mountains, fed completely by precipitation on to the site, site characterization, and recovery of a 20 I m core were provide a new avenue for Antarctic ice-core research. These undertaken in the same field season. In this paper we sites are valuable fo r the recovery of records detailing present the results of site and core c haracterization, climatic change, volcanic acti vit y, and changes in specifically ice surface and ice thickness, bore-hole temp atmospheric chemistry for periods extending well into the erature, mean annual net accumulation, crystal size, crystal last glacial period. Since these si tes are located within the fabric, oxygen-isotope composition, and examples of ice transitional zone between platea u ice and ocean-ice shelf, chemistry (C 1-, SO;-, MSA), and isotopic composition of trapped gases.

1I Joum al of Glaciology

s.p. 85· 5 ICE-SURFACE AN D ICE-THICKNESS MEASUREMENTS

The early part of the field seaso n was devoted to establishing an optimum site for recovery of an ice core (Fig. 2). Maps, visual obser vations of ice-surface topo REE DY GLACIER/ graphy, and the presence of bedroc k ridges all validated initial es timates that the Do minion Range ice cover is either entirely separated from or only minimall y connected to the 80·5 East Antarctic ice sheet and he nce the site is a catchment for local precipitation. E xposed bed roc k ridges flanking the Dominion Range are caverno usly wea th ered . Compariso n of

ROSS ICE SHELF the degree of cavernous weathering with tha t examined in the gene ra l region of the Quee n Maud Mountains by Mayewski and Goldthwait ( 1985 ) sugges ts that ice has not topped these ridges for a t least several tens of thousands of Q years. .. J ", SOU THE RN VIC TOR I A Based on an examina tion of USGS (I: 250 000) LAN D topographic maps and a radio echo-sounding survey

TAYLOR VAL LE Y conducted in th e field , the Dominion Range ice mass is ROSS SEA WR IGH T VA LLEY divisible into three major drainage bas ins, referred to as A, B, and C (Fig. 2). The radio- ec ho survey employed a ~ ICE-F REE AREAS mono- pulse sys tem (after Watts and Isherwood , 19 78) and was cente red primaril y ove r draina ge basin C. It included measurements at 42 statio ns, ten of which were occupied at least twice to test in strume nt reproducibility, which proved to be less than the e rror inherent in reading the oscilloscope. Final ice-thic kness measurements were deter mined using Watts and Ishe rwood's (1978) re lationship with adjustme nts for density made usin g measurements from the core. C revassed areas in the southern section of basin C, lower Vandament Glac ie r, pre vented th e recovery of use ful o 300 600 I I radio echo - sounding data fro m this area. Scale (km) Drainage bas in C surface topography (Fig. 3) is characte rized by a ge ne ral surface slope to the east, thus

Fig. J. Localioll map.

Beardmore Glacier Glacier

w -0 ~ o 1.6 km o co ~ • RadiO Echo Sounding Stollon ® Outer Limits of Radio Echo f> Sound ln9 Survey • Du ll Sile

Ice Su rf ace Contours App rollimate loco lion of C-A DroinoQe Divide (Set fiQute 2) Esllmo t ed Su rface flo wllnes

@--(9 Von do menl Gtacler Flowl lne (see FIQu re 2)

Fig. 3. Drainage basill C ice surface .

N the maj or part of the dra inage fo r C discharges through Vandament Glacier. Ice thic knesses in basin C (Fig. 4) range from ~350 to <50 m with the thickest a reas north of '------' the drill site and in the Mount Tenn ant a rea. Thinner ice ~ 5km areas are found in the western part of the bas in close to the C-A surface ice divide, and th e remainde r of the bas in is characterized by ice d epths most commonly in the range CD Vandament Glaci er Approximate Outline of Relatively Ice Free Terrein 200-300 m. The genera l gradient of the subglac ial ® Koski Glacier topography is east-south-east. Estimated Drainage Di vides @ Rutkowski Glac ier The core site (see Figs 2,3, and 4) was chosen ~1. 7 km AIB,e Ora inage Basins down-flow line from the C-A ice divide to minimize Generalized Surface Flowlines complications due to flo w ri g ht on the divide and ~I. 7 km ® Mt. Tennent Drill Site up-slope from the base camp to minimize the effects of @ Kane Ro cks Outer lim its of Radio Echo any local chemical contamination from the camp. Although © MI. Mills Sounding Sur vey it ca nnot be demonstrated definitive ly with the data @ Mt. Sanders available, it appears that if any East Antarctic ice penetrates ® MI. Ni mrod drainage basin C from the Mount Tennant area that this ice would be deflected eastward toward Vandament Glacier and hence away from the drill site. A comparison between Fig. 2. Domillioll Range localioll map. ice-surface contours (Fig. 3) and ice-thickness contours

12 Maye lV ski al/d 01 hers: Domil1 iol/ Range ice core. Antarclica

(Fig. 4) in the a rea of the Va ndament Glacier flow line suggests that the ice in this area must be stra ined .

BORE-HOLE TEMPERATURE AND MEAN ANNUAL NET ACCUMU L ATION

Te mpe rature measurements were made a t 5 m inte rva ls (Fig. 5) down the entire length of th e bore ho le using a thermistor syste m designed by L. Hansen (PI CO). Twenty readings at 20 s interva ls were made a t each depth immediately f o ll owing a 10 min equilibrium period. Instrument e rro r is ±0.02°C based on duplicate measure ments. The mean a nnual te m pera ture, at 10 m d e pth, is ~ 16 km -37.3°C, a nd the temperature a t the base of the core, 20 1 mba r (m be neath surface), is - 3 1.3°C. R adio echo

• Radio Ecno Sou ndlnQ Slotlon sounding resu lts sugges t that the glac ier at this po int is ® Outer Limits of RadiO Echo <2 30 m thic k, he nce there is little doubt that the base of 50undlnQ Sur ... ey this ice mass is frozen to the bed. ! Dnll SlIe Mea n a nnua l net accumula tio n was dete rmined by a - Ice Thickness Co ntours App ro .l.lmolr Location 01 C-A Surface Ice Oivlde (5ee FiQure 2) combination of measureme nts, including to tal l3- acti vity,

®---® Vo ndomenl GlOClll r Flowllne (S II II FIQu re 21 2IOPb , I4 C, seasonal signatures in ani on c he mistry, and volcanic horizons. Details concern i ng the dating of the core appear in Spe ncer and oth e rs (in press). We re po rt here Fig. 4. Drail/age hasil/ C ice thic!"nesses. onl y the resulta nt mean a nnua l net accumula ti o n fo r the upper "'100 m o f the co re w hic h is "'35 kg m-2 a- I. Temperature Mean Crysta I T he mean a nnual te mpe ra ture and mea n a nnual (OC ) (mm 2 ) accumul atio n a t this si te a re consistent with relationships - 40 - 38 -36 -34 -32 -30 4 5 6 7 8 910 presented by Gow ( 1968) for a s urvey of Anta rc tic s ites. 0 0 20

4 0 CRYST AL SIZE AND FA BR IC 50 60 Hori zontal and vertical thin secti ons were cut f ro m E 8 0 core sa mples taken at depths of 59. 5, 70.7, 85.3, 122.7, '" 10 0 100 143.2, and 190 mba r. Mea n c rys tal size (Fi g. 5) wi thin each ~ 0 120 secti on was d e te rmined fro m measurements of the lo ng and 14 0 short axes of individ ual c rys ta ls. Fabrics ( Fig. 6 ) were 150 16 0 determined fro m measureme nts of e-axis orie ntatio ns usin g a

180 Rigs by sta ge ( La ngway, 1958). Mean crys ta l c ross-secti o n in creased f rom "'7 mm2 at 200 200 59.5 mba r to "'1 3 mm2 at 70.7 m bar and the n decreased 2 Fig. 5. T emperalure. del/ sit)' (s moolhed ). and m ean cryslal progressively to "'2 mm between 70.7 and 143 .2 m bar before 2 si::e as a fUl/clion of depth. in creas in g to "'7 mm at 190 m bar. Secti ons a t 59. 5 and

N N N , " ... e " . ' • . ' . • .. , : .' . '-., .. ."..-( ... .. : " ••*. .* .. ~ .' . . : . .' e. ~ .. .' . • .. .' • % -: • t·- :-- ...... ,····1. l. . ,. ." . . . " " . • A B c S s S N N N .. • e· ...- \ :". 11. e.: e. ... I • .,,:. e.\ ...... \.' . ' . '. ' , ~ : : . '' ." is. . ..~ • e. , .: • . '. .•.. . . . : . .. • '...... •. >... :. .. ,.' ~ .... .'~. -;.", . . " e .:,,: ...... , .. • 'It •• • .. . ' . .. .' o E F s s s Fig. 6. Fabric poil/l-seaL/er d iagram s illuslralil/g c-axis orienlalions al (A) 59.52 mbar. ( 8 ) 70.7 1mbar. ( C ) 85.28 mbar. ( D) 122.65 mbar. ( E ) 143. 18 mbar. al/d ( F) 190.00 mbar. Larger dais represenl cr.l'swls lhal are grealer lhan /wice Ihe average grail/-si::e.

13 Journal of Glaciology

70.7 mbar exhibited random fabrics. At 82.3 mbar, a weakly difference in the distribution of C 1- and SO;- in the upper preferred orientation of c-axes is evident with local c-axis half of the core (2 and 3 cm sampling interval) and one of concentrations of 8% per I % area of projection. By the few intact sections that could be analyzed from the 122.7 mbar, c-axes group into two maxima located approx lower half of the core at 138.0-138.4 mbar (2 cm sampling 0 imately 35 from the vertical. c-axis concentrations as high interval). Marine aerosols and volcanic activity represent the as 10% per I % were observed. At 143.2 mbar, a girdle primary sources for both C 1- and SO;- to the Antarctic ice pattern appears with local c-axis concentrations as high as sheet. While volcanic source inputs would be expected to be 12% per I % area. A ring or small girdle fabric is present randomly distributed in the record, differences in marine at 190 mbar. source input would result in trends in the data series that The marked decrease in size of crystals between 70.7 probably reflect changes in air-mass circulation and/ or and 143.2 mbar may indicate the onset of shearing. ocean/ ice relationships. Average values of CI- ("'250 pp b) Moderate development of c-axis fabrics from the same and SO;- ("'300 ppb) in the 138.0-138.4 m section are two to depth interval might support a shearing process; however, a three times those in the upper half of the core. The lack of tight single-pole fabrics would indicate that shearing contrast between lower-level ice, as represented by the 138.0 is not yet a dominant process. Crystal coarsening at -138.4 m section, and the upper "'100 m of ice is striking. 190 mbar could signal the onset of recrystallization in the Although the higher SO;- and CI - concentrations in the basal layers of ice. However, such a process would tend to deeper sections could co incidently be a volcanic layer, none be impeded by the generally low temperatures at the site. It of the volcanic events in the upper half of the core is as was not possible to obtain azimuthally oriented core and high in concentration or as broad in time span. We this, together with the limited observations of the texture conclude, therefore, that the deeper section marks a pe ri od and fabric of the ice, prevent us from developing a unique which differs from upper sections either in marine source flow history for this part of the Dominion Range ice field. intensity, in transport pathway, and/ or for some unknown Notably, the quality of the ice core recovered deteriorated reason. from whole to fractured core interspersed with whole The upper and lower sections of the core also appear sections from this depth downward. It was not possible in to differ in their concentration of methanesulfonic acid the field, however, to resolve whether the core quality was (MSA). MSA is a constituent of marine aerosols which is necessarily due to strained ice or problems with the formed as a result of the atmospheric oxidation of DMS. cutters. Variations in MSA concentration in the core reflect changes in the flux of DMS from the oceans, in the patterns of aeolian transport, and/or in precipitation rate (Saigne and OXYGEN ISOTOPES OF ICE Legrand, 1987). A noticeable difference was, however, observed between the four samples measured from an upper A continuous SlBO(CE profile was obtained for the ice section of the core (29-30 mbar; MSA conc. = 2.2 ± 0.2) core using 25 cm increments for most of the core and and five samples measured from a lower core section 2-3 cm samples in the sections studied for ice chemistry. (138-139 mbar; MSA conc. = 5.7 ± 1.0). 61BOI~ is defined here as being equal to (eBO/ 160)sample - B 16 eBO/ 0)SMOW)/ e O / 0)SMOW and SMOW is Standard Mean Ocean Water. 61BO(CE for 50 cm averages of the data appear ISOTOPIC COMPOSITION OF TRAPPED GASES in Figure 7. The isotopic composition of trapped O 2 and N2 in two -38,------, sections of the Dominion Range core appear in Table I. The isotopic composition of the 83 mbar samples was similar to the isotopic composition of Recent « 1500 a B.P.) samples of ice from five different cores taken from Antarctica and -40 Greenland (paper in preparation by T. Sowers and others). The isotopic compOSItIOn of the 139 mbar samples had 1B 6 O ATM(02) va lues which were enriched, compared to Recent ice samples, by 1.0 ± 0.13 %0. 0 -42 During the tranSItIOn from glacial to interglac ial ~ 0 periods, isotopically light melt water from glaciers was ro ~ introduced to the oceans, resulting in a decrease in the 1B 0 61BOwater of sea-water (where 6 O t «H/Bo/ -44 16 18 16 3 wa er ro H2 0)wate/(H2 0 / H2 0SMOW) I) I 0 ). Photosynthesizing organisms utilized the isotopically depleted melt water to form O which was mixed into the paleoatmospheric O 2 lB 2 -46 reservoir causing the o O ATM(02) of air to fall (whe re 1B 6 O ATM(02) = «IB0160)/e602)paleo_ai/«eBOI60)/e602)present_ 3 day atmosphere) - I) I 0 ). Studies of the trapped gases 111 the Dome C core have shown that the isotopic composition of -48+------,------.-----~---r------~ O2 trapped in the ice tracks the isotopic composition of o 50 100 150 200 sea-water over the past 20000 years (Bender and others, 1B Depth, m 1985). Since the 6 O ATM(02) is constant throughout the atmosphere, one can use tlie composition of the O2 in the ice as a chronologic tool. We have used this tool to estimate Fig. 7. olB O(CE measuremellt s dowll-core (50 cm averages). the ages of two samples from the Dominion Range core. Analysis of Recent samples of ice show that the For the upper "'100 m of the core there appears to be trapped gases are enriched in both 1BO and 15N relative to a small trend toward less negative olBO(CE values with the contemporaneous atmosphere (paper in preparation by T. depth. The sections below "'100 m are significantly lighter Sowers and others). The enrichment is probably the result and are marked by a drop of "'5 %0 from "'100 to 145 mbar of isotopic fractionation as the bubbles are sealed. Because 15 followed by a rise of "'2-3%0. The "'5.0%0 marked drop is atmospheric N2 has a very long residence time, the 0 N of similar to the glacial/ interglacial 6 changes of 5.4 %0 and the atmospheric N2 is believed to have been constant for 6 4 about 5%0 observed at Dome C (Lorius and others, 1979) the last 10 years (where 615NATM(N2) = (e N 15N/ 14N ) . / (e4NI5N/ 14N ) . - 1)103). Given and at Vostok (Lorius and others, 1985), respectively. 2 paleo-alr 2 prese!J.tsd.y f/f, this constancy, and the observed 6 N-S 0 relationship for gases trapped in modern ice, one can use the fraction ICE CHEMISTR Y ation of the N2 trapped in ice to determine the 1B 6 O ATM(02) of past atmospheres using the following equa While details of the distribution of major chemical tIOn: species in the core are left to other papers (e.g. Spencer 1BO and others, in press), it is worth mentioning the marked 6 ATM(02)

14 MayelVski alld vlhers: Domillioll Rallge ice co re , AlllarClica

TABLE l. ISOTOPIC COMPOSITION OF TRAPPED GASES IN DOMINION RANGE LCE

cl5N * u ICE(N 2) 83 mbar sampLe (11 = 2) Average 0.17%0 0.37%0 -0.07%0 std. dev. ±0.01 %0 ±0.02%o ±O .OI %o

139 mbar sample (11 = 7) Average 0.13%0 1.35 %0 1.00%0 std . dev. ±0.05%o ±0.02%o ±0.13 %o

* Reported data have been corrrected for the iso topic dependence on th e elemental composition (paper in prepar;ttion by A.B. Kiddon and others). The data are reported relative to present-day-air, S15N.

t Isotopic composition of the contemporaneous atmosphere from which the trapped gases were derived, also reported relative to present-day air.

lB Knowing the & O ATM(02)' one can estimate the age of an Future papers will document details of the Holocene signal unknown trapped gas sample by comparing the measured in this region. lB & O ATM(02) value with the down-core record of lB & O ATM(02) measured in the Dome C core (Bender and others, 1985). Using this &lBOICE(02) curve, we assign an ACKNOWLEDGEMENTS ice age for the 139 mbar sample 01 > 10 ka B.P. This age is expressed as a lower limit for two reasons. First, ice is We should like to thank J.V. James (Glacier Research older than the age of the trapped air (Schwander and Group), H. Rufli (Switzerland). and B. Koci (Polar Ice Stauffer, 1984 ). Secondly, th e SlBOICE(Q3) va lues for the Coring Office) for their help and friendship in the field. Dome C record were not converted to b 0ATM(02) due to PLCO ably recovered the 20 I m core. L. Hanse n (PICO) lack of &15N1CE(Ns) measurements. Converting tne 'Dome C designed and provided the thermistor system used in this &lBOICE(02) to & °ATM(02) values will shift the inferred study. Thanks are also due to VX£-6. J. Dibb (Glacier IB & O ATM(02) record closer to the present-day air. By con Research Group) conducted the 2lOPb and total !3-activity lB verting the Dome C & O'CE(02)' one would in crease the measurements and A. Wilson (University of Arizona) the l4C ;tge of the Dominion Range 139 mbar samples. analysis which were intrumental in the dating of the upper sections of this core. We are greatl y indebted to them for th eir input. L. Preble patiently typed this paper. This re SUMMARY AND CONCLUSIONS search was supported by U.S. National Science Foundation grants DPP-84-00574, DPP-84-11108, and DPP-85-13699. The Dominion Range ice-core site is characterized by a mean annual temperature of -37.3°C and a core-base temperature of -31.3°C which is probably close to the basal ice temperature. The mean annual net accumulation is REFERENCES "'35 kg m-2 a-I Dominion Range ice is divisible into three main Angelis, M. de, M. Legrand, J.R. Petit, N.!. Barkov, Ye.S. drainage systems and a site close to the ice divide between Korotkevitch, and V.M. Kotlyakov. 1984. Soluble and two of these drainage systems was chosen for the recovery insoluble impurities along the 950 m deep Vostok core of a 20 I m core. Differences between ice-surface and (Antarctica) - climatic implications. J . Atmos. Chem., I , subglacial gradients in the area of the drill site suggest that 215-239. some amount of lateral strain is imposed on the ice column. Bender, M., L.D. Labeyrie, D. Raynaud, and C. Lorius. IB The difference in & O'CE noted from "'100 to 1985. Isotopic composition of atmospheric 02 in ice linked "'145 mbar in the Dominion Range core is si milar to the with deglaciation and global primary productivity. Nature, glacial/ interglacial & changes observed at Dome C and 318(6044), 349-352. Vostok. Measurement of &I80ICE(02) and &I5NICE(N2) of Cragin, J .H., M.M. Herron, C.C. Langway, Jr, and G. trapped gases indicates that ice at 139 mbar has an age Klouda. 1977. Interhem ispheric comparison of changes >10 ka B.P. in the composition of atmospheric precipitation during the If, as inferred from the measurements of &lBOICE' Late Cenozoic era. III Dunbar, MJ., ed. Polar Ocealls. IB 15 & O'CE(02)' and & N'CE(N2)' the upper approximately half Proceedillgs 0/ the Polar Ocealls COIl/erellce ... MOlltreal, of the core column is Holocene in age and the ice below is May, 1974. Calgary, Arctic Institute of North America, glacial, then differences in both crystal size and chemical 617-631. concentration disc ussed in this text may be more uniquely Denton, G.H., R.L. Armstrong, and M . Stuiver. 1971. The defined. While decreases in crys tal size in the lower ice Late Cenozoic glacial history of Antarctica. III Turekian, may be due partly to shear, they may also simpl y reflect K .K., ed. The Lale Cello::;oic glacial ages. New Haven, the cooler temperature of formation present during the CT, and London, Yale University Press, 267-306. glacial period as observed at Dome C (Duval and Lorius, Drewry, DJ. 1980. Pleistocene bimodal response of 1980). Furthermore, increases in C I- and SO!- concentra Antarctic ice. Nalure, 287(5779), 214-216. tions may be consistent with in creases from Holocene to Duval, P. and C. Lorius. 1980. Crystal size and climatic glacial age as measured from the Byrd core (Ragone and record down to the last ice age from Antarctic ice. Earth Finelli, 1972; Cragin and oth ers, 1977) and Vostok core Plane!. Sci. Lell., 48( I), 59-64. (Angelis and others , 1984), and th e trend in MSA concen Gow, A.J . 1968. Deep core studies of the accumulation and tration is similar to that observed from Holocene to glacial densification of snow at Byrd Station and Little America ice measured at Dome C by S;tig ne and Legrand (1987). V, Antarctica. CRREL R es. Rep. 197. The Dominion Range ice co re provides relatively easy Langway, C.C., Jr. 1958. Ice fabrics and the universal access to the Holocene record in a site that is potentially stage. SIPRE Tech. R ep. 62. climatically sensitive. Were the quality of the lower half of Lorius, c., L. Meriivat, J . Jouzel, and M. Pourchet. 1979. A the core better, it could also provide a view through the 30,000-yr iso tope climatic record from Antarctic ice. interglacial/glacial trans ition and into the last glacial period. Nature, 280(5724), 644-648.

15 Joumal of Glaciology

Lorius, c., alld 6 others. 1985. A 150,000-year climate Schwander, 1. and B. Stauffer. 1984. Age difference between record from Antarctic ice. Nature, 316(6029), 591-596. polar ice and the air trapped in its bubbles. Nature, Mayewski, P.A. and R.P. Goldthwait. 1985. Glacial events 311(5981), 45-47. in the Transantarctic Mountains: a record of the East Spencer, M.J ., P.A. Mayewski, W.B. Lyo ns, M.S. Twickler, Antarctic ice sheet. /11 Turner, M .D. and J.F. and P. Grootes. In press. A 3500 year ice chemistry Splettstoesser, eds. Geology of the Transalltarctic record from the Dominion Range, Antarctica: linkages Moulllaills. Washington, DC, American Geophysical Union, between climatic variations and precipitation chemistry. 275-324. (Antarctic Research Series 36.) Stuiver, M., G.H. Denton, T.J. Hughes, and J .L. Fastook. Ragone, S.E. and R.V. Finelli. 1972. Cationic a nalysis of 1981. History of the marine ice sheet in West Antarctica the Byrd Station, Antarctica, ice core. CRREL Spec. Rep. during the last glaciation: a working hypothesis. /11 180. Denton, G.H. and T.J. Hughes, eds. The last g reat ice Saigne, C. and M . Legrand. 1987. Measurements of sheets. New York, etc., 1. Wiley and Sons, 319-436. methanesulphonic acid in Antarctic ice. Nature, 330(6145) , Watts, R.D. and W. Isherwood. 1978. Gravity surveys in 240-242. glacier-covered regions. Geophysics, 43(4), 819-822.

MS. received 24 March 1988 and ill revised form 10 May 1989