Technical papers in hydrology 4

In this series:

1 Perennial Ice and Snow Masses. A Guide for Compilation and Assemblage of Data for a World Inventory.

2 Seasonal S n o w Cover. A Guide for Compilation and Assemblage of Data for Measurement and Mapping.

3 Variations of Existing Glaciers. A Guide to International Practices for their Measurement.

4 Antarctic Glaciology in the International Hydrological Decade.

5 Combined Heat, Ice and Water Balances at Selected Glacier Basins. A Guide for Compilation and Assemblage of Data for Glacier Mass Balance Measurements.

A contribution to the International Hydrological Decade

Antarctic glaciology in the International Hydrological Decade

unesco /iash

The selection and presentation of material and the opinions expressed in this publication are the responsibility of the authors concerned and do not necessarily reflect the views of Unesco. N o r do the designations employed or the presentation of the material imply the expression of any opinion whatsoever on the part of Unesco concerning the legal status of any country or territory, or of its authorities, or concerning the frontiers of any country or territory.

Published in 1969 by the United Nations Educational, Scientific and Cultural Organization Place de Fontenoy, 75 Paris-7e. Printed by Imprimerie-Reliure Marne

© Unesco/IASH 1969 Printed in France S C . 6 8 / X X I . 4 / A

Preface

The International Hydrological Decade ( IHD) , 1965-74, was launched by the General Conference of Unesco to promote international co-operation in research and studies and the training of specialists and technicians in scientific hydrology. Its purpose is to enable all countries to m a k e a fuller assessment of their water resources and a more rational use of them as m a n ' s demands for water constantly increase in face of developments in population, industry and agriculture. In 1968 National C o m m i t ­tees for the Decade had been formed in 100 of Unesco's 122 M e m b e r States to carry out national activities and to contribute to regional and inter­national activities within the programme of the Decade. The implementation of the programme is supervised by a Co-ordinating Council, composed of twenty-one M e m b e r States selected by the G e n ­eral Conference of Unesco, which studies proposals for developments of the programme, recommends projects of interest to all or a large number of countries, assists in the development of national and regional projects and co-ordinates internatio­nal co-operation.

Promotion of collaboration in developing hydro-logical research techniques, diffusing hydrological data and planning hydrological installations is a major feature of the programme of the I H D which encompasses all aspects of hydrological studies and research. Hydrological investigations are encourag­ed at the national, regional and international level to strengthen and to improve the use of natu­ral resources from a local and a global perspective. The programme provides a means for countries well advanced in hydrological research to exchange scientific views and for developing countries to benefit from this exchange of information in elab­

orating research projects and in implementing recent developments in the planning of hydrolo­gical installations.

A s part of Unesco's contribution to the achieve­ment of the objectives of the I H D the General Conference authorized the Director-General to collect, exchange and disseminate information concerning research on scientific hydrology and to facilitate contacts between research workers in this field. T o this end Unesco has initiated two collections of publications 'Studies and Reports in Hydrology' and 'Technical Papers in Hydrology'.

The collection 'Technical Papers in Hydrology' is intended to provide a means for the exchange of information on hydrological techniques and for the co-ordination of research and data collection.

The acquisition, transmission and processing of data in a manner permitting the intercomparison of results is a prerequisite to efforts to co-ordinate scientific projects within the framework of the I H D . The exchange of information on data collected throughout the world requires standard instru­ments, techniques, units of measure and termino­logy in order that data from all areas will be c o m ­parable. M u c h work has been done already toward international standardization, but m u c h remains to be done even for simple measurements of basic factors such as precipitation, snow cover, soil mois­ture, streamflow, sediment transport and ground­water phenomena.

It is hoped that the guides on data collection and compilation in specific areas of hydrology to be published in this collection will provide means whereby hydrologists m a y standardize their records of observations and thus facilitate the study of hydrology on a world-wide basis.

Contents

I

n m IV

V

VI

Foreword

Hydrology and glaciology

Precipitation

Evaporation, melting, snow drift

Stage ('ice thickness')

Slope-stage-discharge ('ice flow')

Conclusion

References

9

11

12

13

13

14

15

15

Foreword

This survey of Antarctic glaciology in the Interna­tional Hydrological Decade (IHD) is presented by Unesco in the series 'Technical Papers in Hydro­logy'. In accordance with the recommendations of the I H D Working Group on World Water Balance, advice was sought of the Scientific C o m ­mittee on Antarctic Research ( S C A R ) concerning the possibility of the participation of this committee in the programme of the International Hydrolo­gical Decade.

A s a result, this hydrological appraisal of gla-ciological research in Antarctica was prepared by the Secretary of the S C A R Working Group on Glaciology and reviewed and approved by the

working group at its meeting in Berne (Switzer­land) on 4 October 1967 during the fourteenth General Assembly of the International Union of Geodesy and Geophysics. The points of view adopted in this publication, facts stated and opi­nions expressed with regard to those facts are the responsibility of the authors and do not necessa­rily reflect the views of the Secretariat of Unesco.

It is hoped that this publication will give added emphasis to the important role that Antarctic glaciological studies play in efforts to attain a c o m ­plete understanding of the hydrological cycle and to establish the World Water Balance.

9

T h e programme of the International Hydrological Decade ( I H D ) provides for the study of snow and ice (including mountain glacier systems) which form significant components of m a n y hydrological sys­tems. However , no specific mention is m a d e in the programme of the continental ice sheets of Green­land and especially Antarctica. This is fully consis­tent with the I H D ' s emphasis on inhabited continental areas and in effect ranks the ice sheets alongside the oceans as important links in the hydrological cycle but remote from immediate year-to-year hydrological affairs.

Yet the fact that almost all the world's fresh water is locked u p in the Antarctic ice1 m a k e s it difficult

I Hydrology and glaciology

T o delineate the scope and limits of this survey it is convenient to start from the basic hydrological concept of hydrograph, which describes the local response of a hydrological system to a precipita­tion input. T h e hydrograph defines a character­istic time-scale, e.g. the time between the onset of precipitation and the return of the recession to the base flow level, which in general does not exceed a few days, i.e. less than 1 per cent of the I H D .

In glaciology the effect of precipitation changes on the flow of glaciers and ice sheets has been investi­gated especially by N y e (1960) on the basis of Lighthill and W h i t h a m ' s (1955) generalized treat­ment of flows governed by Seddon's law. T h e central concept of the Lighthill-Whitham-Nye theory is .the 'kinematic wave ' , which at a given point in space again produces an (ice) hydrograph. Its time-scale turns out to depend mainly on the change in flow velocity along the flow ('longitu­dinal strain rate'). For continental ice sheets the response time is measured in thousands of years,

to exclude Antarctica from any discussion of world­wide hydrological p h e n o m e n a and problems. In addition, Antarctica's control of the atmospheric circulation and the clues contained in the ice to past climatic events and present trends ultimately need to be considered as part of the Decade's deliberations.

This hydrological survey of glaciological research in Antarctica includes the following topics: pre­cipitation, evaporation, melting and snow drift, ice thickness and ice flow. Hydrological termino­logy has been used throughout the report and glaciological equivalents, where they exist, are given in inverted c o m m a s .

while even mountain glaciers normally require from three to thirty years to dispose of abrupt increases in precipitation. In the rare 'catastrophic glacier advances' this m a y be reduced to a matter of weeks.

T h u s the I H D , which comprises a large n u m b e r of separate hydrological events, represents but a m o m e n t on the glaciological time-scale. This limits Antarctic glaciological research to the fol­lowing standard hydrological topics: precipitation ('accumulation'); evaporation and other local losses ( 'ablation ') ; stage ( 'ice thickness ') ; and slope-stage-discharge information and relationships ('ice flow and flow laws'). A t the same time the rela­tive immutability of the flowing m e d i u m offers

1. The Antarctic ice is estimated to contain 33 x 10' k m * of water as compared with 0.3 x 1 0 ' k m 3 of fresh surface water, 0.15 x 10s km» of underground water, 0.03 x 10' k m * of water vapour in the atmosphere. The oceans contain approxi­mately, 1,400 x 10* k m * of salt water. (Estimates from Bauer and Lorius (1964).)

11

Antarctic glaciology in the International Hydrological Decade

possibilities for the study of its chemical and physical properties at a given point or vertical; such possibilities do not exist in hydrology.

The ultimate aim in Antarctic glaciological research as in hydrology generally is the solution of storage equations, or routing of the ice flow through the major drainage basins of the Antarctic continent which have been outlined and defined by Giovinetto (1964). The more immediate task the S C A R Working G r o u p on Glaciology has set itself is equivalent to determining whether various basins and Antarctica as a whole are located on the rising or receding limbs of their hydrographs at present ( 'local and general Antarctic mass budgets ').

Only the basic approach and some outstanding results for each of the major fields of Antarctic

II Precipitation

Antarctic precipitation occurs almost completely in the form of ice crystals and in the presence of strong winds. The difficulties of measuring such precipitation are well k n o w n and have not yet found a satisfactory solution although the better understanding of the wind transport of snow (Budd, Dingle and Radok , 1966) holds out a pro­mise of such a solution. However the relative per­manency of the precipitation deposited on the Antarctic continent makes it possible to measure the effective water gain ('net accumulation') simply by means of staff gauges ('stakes') read from an arbitrary datum level. A large amount of such direct effective precipitation measurements is n o w avail­able for the surroundings of the stations which have operated in Antarctica since the I G Y .

Various means exist for estimating the precipi­tation for the remainder of the Antarctic continent. Seasonal temperature changes leave their m a r k both on the structure of the accumulating snow and on its chemical and physical characteristics. The feasibility of identifying annual layers in pit walls was first discovered by members of W e g e ­ner's Greenland expedition during their first win­tering on a polar ice sheet in a snow cave. In Antarctica the direct structural identification of annual layers works reasonably well near the coast where melt lenses or layers of distinctly less cohe­sive crystals form during the summer . Inland this

glaciological inquiry can be given here. Reviews of this research have been published by Robin (1958, 1960), Loewe(1961, 1965), Bauer and Lorius (1964), and G o w (1965). The United States pro­g r a m m e is reviewed fully each year in two issues of the Antarctic Journal of the U.S.A. (starting with Vol. 1, N o . 4, 1966). Extensive date compilations have been published by the American Geographical Society (Bentley et al., 1964) and by the Academy of Sciences of the U . S . S . R . (1966). The most recent survey by Loewe (1967) summarizes the hydrolo­gical implications and contains a full list of refer­ences. The International Symposium on Antarctic Glaciological Exploration (IS-AGE) , held at H a n ­over (United States), in September 1968, will pro­vide a further major summary of progress.

approach becomes increasingly haphazard, and methods utilizing the temperature dependence of relative isotope abundance are n o w generally used to determine annual layers. These methods have been surveyed by Picciotto (1962) and Lorius (1963, 1964) and go beyond their immediate purpose in clarifying, e.g. the process of direct sublimation of moisture in the interior of Antarctica (Epstein, Sharp and G o w , 1965). For the determination of past precipitation values and trends an important advance in radiocarbon technique (Oeschger et al., 1966) has recently opened the way to direct dating of the C 0 2 in air bubbles contained in 1-ton ice samples which can be obtained from a given level in a bore-hole. Combined with temperature m e a ­surements in the deep bore-holes n o w feasible (e.g. the 1,400 m hole drilled through the Greenland ice cap in June 1966 and one expected to be achieved through 2,700 m of ice at Byrd, Antarctica, next summer) such precipitation data will provide for the first time a detailed history of the Antarctic climate at least during and since the last major glaciation.

Present-day precipitation levels for Antarctica are especially clearly defined by the level of abrupt increase in tritium following the start of fusion b o m b testing in 1954. This and all other informa­tion points to a m e a n effective rate of water acqui­sition ('net accumulation') of around 15 cm/year

12

Antarctic glaciology in the International Hydrological Decade

(with values as high as 1 m/year in some mountain regions and less than 5 cm/year on the central East Antarctic plateau) or a total of 2 x 1 0 s k m 3

for the whole of Antarctica. This figure should be compared with Wiist's estimate of the annual pre-

III, Evaporation, melting, snow drift

In contrast to the normal hydrological picture in which evaporation and évapotranspiration account for two-thirds of the precipitation these local losses in Antarctica are generally quite insignificant c o m ­pared with the quantities of water involved in ice flow. This is largely due to the fact that temperature is the dominant controlling factor for evaporation (Budd, 1967a), with wind playing a strong support­ing role especially in the coastal regions subject to gravity ('katabatic') flow. Evaporation and melt losses there can reach 50 cm/year or more, but in general m u c h smaller quantities are involved. Moreover, any melt water will tend to refreeze in the cold ice below and not contribute to run-off. Apart from contributing to effective evaporation, snow drift inland leads to a redistribution of pre­cipitation but involves only a small fraction of the water involved in ice flow. At the coast it has been estimated that the precipitation blown out to sea amounts to no more than a few per cent of the pre­cipitation.

IV Stage ('ice thickness')

The measurement of ice thickness in different parts of the ice sheet remains one of the primary tasks of Antarctic expeditions but is n o w approaching a new phase, both technically and in emphasis. The broad details of the Antarctic storage basin ('base rock and ice surface topographies') have become k n o w n from and since the I G Y and only a few of the most remote regions in Eastern Antarc­tica remain to be surveyed. The seismic spot sound­ing technique supplemented by measurements of gravity is about to be replaced by radar sounding which can be carried out continuously from an aircraft and has already provided not only a wealth

cipitation on the inhabited continents, 106 k m 8 , and shows Antarctica to be the driest continent of all, with less than one half even of Australia's annual precipitation.

A s in the case of precipitation the immediately significant hydrological information on local losses can be obtained by staff-gauge ('stake') measure­ments of variations in relative stage ('net ablation'). While practically all of Antarctica shows an excess of precipitation over local losses, there are regions where the reverse is the case and has produced ice free areas ('oases, dry valleys') or blue ice slopes. Evaporation can be measured directly on such ice slopes which also have served to clarify the involv­ed heat transfers arising from the transparency of ice and to a lesser extent snow (Schwerdtfeger and Weiler, 1967). Complete heat budget studies have been carried out under these conditions by Weiler (1967) for comparison with those of the Antarctic interior (especially at the new Plateau station located in 80° S., 40° W . , where the ice surface is at a height of 3,630 m and the m e a n surface air temperature around — 60° C ) where the precise roles of evaporation and sublimation are not yet k n o w n .

of n e w topographical details but also so far unex­plained evidence of layering in the ice (Evans, 1966). Following a suggestion due to Robin this 'radio echo sounding' m a y eventually form the basis for a complete survey of the Antarctic water storage from a satellite.

For the m o m e n t the emphasis in Antarctic stage measurements is on details of complex glacier sys­tems and for the regions of submerged obstacles. In addition precise surveys are being carried out in support of studies of the central problem of ice discharge through the major drainage basins and from the continent as a whole.

13

Antarctic glaciology in the International Hydrological Decade

V . Slope-stage-discharge ('ice flow')

Studies of natural ice flow and deformation are n o w in the forefront of Antarctic glaciological research. In contrast to hydrological discharge for­mulae in which the stage variable enters only as a substitute for the surface slope or fall variable, and with an exponent normally not very different from its theoretical value of 1/2, the flow law of glaciers and ice sheets contains the ice thickness and the surface and bottom slopes, with exponents which depend on these variables. In addition the basic flow properties of ice are strongly temperature dependent and there is evidence that they undergo a drastic change especially close to the melting point (Barnes and Tabor, 1966; Barnes and Robin, 1966). Finally the ice motion consists in part of bed slid­ing which is believed by some workers to depend crucially on the presence or absence of melt water at the rock interface (Lliboutry, 1965; Weertman, 1966).

Progress towards a full understanding of such a complicated physical system of conditions depends above all on ample and precise ice flow measure­ments, but in Antarctica these are difficult to achieve except near the rare mountains or rock outcrops ('nunataks'). Over the large featureless expanses of the ice sheet, increasing use is being m a d e of radar distance measuring devices ('tellurometers') to determine the surface deformation of the ice. For example, the South African expedition contin­uing the I G Y work of the Norwegian Antarctic Expeditions from Norway and Sanae stations near 70° S., 2° W . , has a programme of deformation surveys on the Fimbul ice shelf, the floating ice sheet which drains the Jutol glacier system, and plans for similar work on the Troll ice tongue. These programmes are supplemented by ice thick­ness, gravity, accumulation, and heat budget m e a ­surements and together with cartographic work will provide in due course a complete hydrolo­gical picture of an important Antarctic drainage basin.

The first stage of a corresponding programme was recently completed by the Australian Antarctic Expedition for the A m e r y ice shelf at the outlet of the largest single glacier (Lambert glacier) in Antarctica (Budd, 19676). This work is about to move into the next stage where more precise defor­mation measurements will be supplemented by radio

ice thickness soundings and core drilling through the bulk of the ice shelf in two separate places. This is expected to provide a variety of information on the internal deformation of the ice, on its tempera­ture distribution, and on the magnitude of melting or accretion at the bottom of the ice which repre­sents an almost unknown quantity in the Antarc­tic hydrological cycle at present.

Apart from studies concerned with these and m a n y other drainage basins (notably those of the Ross Sea region, cf. Giovinetto, Robinson and Swithinbank, 1966) attention has also been given to the flow of the main Antarctic ice sheet. S h u m -skiy, Kotlyakov and Evteev (1961) (cf. also S h u m -skiy, 1963) used the 15 k m diameter ice cap on Drygalski Island as a small-scale natural model of an ice sheet. A t the other end of the scale deforma­tion measurements were started by Russian and French glaciologists in 1963-64 on a major flow line of the Antarctic ice sheet itself between Vostok and Mirny (Shumskiy and Bauer, 1965). The results of these full-scale measurements are not yet available. O n the other hand an intermediate scale project, the Australian survey of the 200 k m diameter, 1,200 m thick Wilkes ice d o m e (Budd, 1966; McLaren, 1966) has just provided the first concrete indications on the hydrological trend at the edge of the Antarctic continent and will serve as a final illustration of the scope and sophistica­tion of present-day glaciological research in Antarc­tica.

The Wilkes d o m e has an almost semicircular shape on the side adjoining the Southern Ocean and is separated from the main Antarctic ice sheet by a deep fjord occupied by major ice streams flowing around the d o m e towards the north-west and north-east. The d o m e can therefore repre­sent an isolated hydrological system which at the same time is large enough to produce its o w n cha­racteristic climate and distribution of precipitation. The survey is based on a 300 k m triangle formed of staff gauges set 1.6 k m (1 mile) apart and with its apex near the centre of the d o m e . Deformation rosettes have been set up at various points of the triangle and the entire system has been surveyed three times by tellurometers and optical levelling. The results of these measurements together with net precipitation readings and ice thickness obser-

14

Antarctic glaciology in the International Hydro-logical Decade

vations1 are beginning to provide a full hydrolo-gical picture of this storage—its total water content, its deformation and discharge, and its change in surface shape. Apart from providing confirmation for theoretical slope-stage-discharge relationships the analysis indicates that the d o m e is subsiding at the centre, having less net precipitation or a higher discharge than needed for the re-charge of the stor­age. This is in opposition to the tendency deduced by various approximate calculations for the main Antarctic storage where precipitation appears to exceed the rate at which the ice is discharged towards the edge of the continent. Together these contrast­ing trends could reflect the growth of a flood wave to be discharged from the Antarctic continent in centuries to come, but clearly m a n y more regional studies are needed before this picture can be accept­ed as realistic.

In such work temperature profiles are destined to

VI Conclusion

Detailed consideration has been given in the last section to some current and future projects in order to illustrate the present trend to increasingly c o m ­plex work in Antarctic glaciology. The need for this is imposed by the medium and creates a distinc­tion from the general work of the I H D , with its emphasis on the practical aspects of hydrology.

References

A C A D E M Y O F S C I E N C E S O F T H E U . S . S . R . 1966. Atlas Antark­tis I.

B A R N E S , P . ; T A B O R , D . 1966. Plastic flow and pressure melt­ing in the deformation of ice, I. Nature, vol. 210, no. 5039, p. 878-83.

; R O B I N , G . de Q . 1966. Implications for glaciology. Nature, vol. 210, no. 5039, p. 883.

BENTLEY, C. R.; CAMERON, R. L.; BULL, C ; KOJIMA, K . ; G o w , A . J. 1964. Physical characteristics of the Antarctic ice sheet, American Geographical Society. (Antarctic M a p Folio Series, Folio 2.)

B A U E R , L . ; L O R I U S , C . 1964. The polar ice caps. Impact, vol. 14, no. 4, p. 223-38.

B U D D , W . 1966. Glaciological studies in the region of Wilkes, Eastern Antarctica, 1961. A.N.A.R.E. scientific reports, ser. A(IV) Glaciology, pub. no. 88.

. 1967a. Ablation from an Antarctic ice surface. Proc. Int. Conf. on Low Temperature Science, Hokkaido Uni­versity, Sapporo.

m a k e á special contribution. The internal ice tem­peratures result from molecular conduction and laminar advection of heat (both along the ice sheet and in the vertical), processes which are m u c h easier to treat theoretically than the turbulent trans­fers normally encountered in hydrology. The tem­peratures that will be measured in the deep drill holes and by a new melt sonde (the 'Philbert probe', which also measures directly the internal velocity profile of the ice flow) are relevant to the understand­ing of the ice flow and in addition reflect the cli­matic history of the ice although m a n y disturbing influences need to be removed to m a k e this clearly visible (Robin, 1966). Such information on past climatic trends and changes offers perhaps the best hope of a clue to the new climatic phase which appears to have set in just prior to the start of the I H D (Lamb, 1966).

Nevertheless there seems every reason to believe that well before the end of the Decade, its main stream of inquiry and Antarctic glaciological research will have to converge if a firm interpreta­tion of the world's hydrological problems is to be achieved by the I H D .

B U D D , W . 19676. The Amery ice shelf. Proc. Pacific Science Congress, Symposium on Meteorology of Snow and Ice.

; D I N G L E , R . ; R A D O K , U . 1966. The Byrd snow drift project—outline and basic results. Studies in Antarctic meteorology, vol. 9, Antarctic Research Series, American Geophysical Union.

E P S T E I N , S.; S H A R P , R . P . ; G o w , A . J. 1965. Six-year record of oxygen and hydrogen isotope variations in South Pole firn. / . geoph. Res., vol. 70, no. 8, p. 1809-14.

E V A N S , S. 1966. Progress report on radio echo sounding. Polar record, vol. 13, no. 85, p. 413-20.

G I O V I N E T T O , M . B . 1964. The drainage systems of Antarc­tica: accumulation. Antarctic snow and ice studies, vol. 2, Antarctic Research Series, American Geophysical Union.

1. So far made by seismic and gravity techniques; a radio ice thickness survey of the triangle is due to be carried out later this year.

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Antarctic glaciology in the International Hydrological Decade

GIOVINETTO, M . B ; ROBINSON, E. S. ; SWTTHINBANK, C. W . M . 1966. The regime of the western part of the Ross ice shelf drainage system. / . Glac, vol. 6, no. 43, p. 55-68.

G o w , A . J. 1965. The ice sheet. Antarctica, Methuen. L A M B , H . H . 1966. Climate in the 1960s. Geogr. J., vol. 132,

part 2, p. 183-212. L I G H T H I L L , M . J.; W H I T H A M , G . B . 1955. O n kinematic

waves. Proc. Roy. Soe, ser. A , vol. 229, p. 281-345. L L I B O U T R Y , L . 1965. Traité de glaciologie, vol. 2. Paris, M a s -

son. L O E W E , F . 1961. Fortschritte in der physikalisch-geographi­

schen Kenntniss der Antarktis. Erdkunde, vol. 15, Lfg. 2, p. 81-92.

. 1965. Arktis und Antarktis im Lichte neuerer For­schung. Polarforschung, vol. 5, Heft 1/2, p. 225-35.

. 1967. The water budget in Antarctica. Proc. Symp. on Pacific-Antarctic Sciences, p. 101-10. (JARE Sc. Reports, special issue no. 1.)

LoRTUS, C . 1963. L'utilisation des isotopes dans l'étude glacio-logique des calottes polaires. (Expéd. Polaires Françaises, Piibl. 253.)

. 1964. Isotopes in relation to polar glaciology. Polar record, vol. 12, no. 77, p. 211-22.

M C L A R E N , A . 1966. Ice cap study, Wilkes, Antarctica. Antarctic, vol. 4, no. 8, p. 393-5.

N Y E , J. F . 1960. The response of glaciers and ice sheets to seasonal and climatic changes. Proc. Roy. Soe, ser. A , vol. 256, p. 559-84.

OESCHGER, H . , A L D E R , B.; LOOSLI, H . ; L A N G W A Y , C . C. Jr.; R E N A U D , A . 1966. Radiocarbon dating of ice. Earth and planetary science letters, vol. 1, p. 49-54.

PicciOTTO, E . 1962. Notes on isotope glaciology. Polar record, vol. 11, no. 71, p. 206-8.

R O B I N , G . de Q . 1958. Geophysical studies in polar regions: The Antarctic ice sheet. Geophys. J. Roy. Astron. Soc, vol. 1, no. 3, p. 347-51.

. 1960. Progress report on the Antarctic ice sheet. Polar record, vol. 10, no. 64, p. 3-10.

. 1966. Origin of the ice ages. Sei. J., June. S C H W E R D T F E G E R , P . ; W E L L E R , G . 1967. The measurement of

radiative and conductive heat transfer in snow and ice. Arch. Met. Geophys. u. Biokl., ser. B , vol. 15, no. 1, p. 24-38.

S H U M S K I Y , P . A . 1963. O n the theory of glacier variations. Bull. Int. Assoc. Sc. Hydr., vol. 8, no. 1, p. 45-56.

; K O T L Y A K O V , V . M . ; E V T E E V , S. A . 1961. Lednikovyi cupol ostrova Drygalskogo. Glaziologicheskiye Issledova-niye MGG, no. 6, p. 45-69.

; BALIER, A . 1965. Issledovaniye covremennykh izmene-nii tsentralnoi chasti lednikovo pokro va Vostochnoi Antark-tidy. Bull. Sov. Ant. Exped., no. 51, p. 37-51. (English translation publ. by Elsevier.) Cf. also A . Bauer's account in La Houille Blanche, no. 5, August-September, 1965, p. 115-24.

W E E R T M A N , J. 1966. Effect of a basal water layer on the dimensions of ice sheets. / . Glac, vol. 6, no. 44, p. 191-207.

W E L L E R , G . 1967. The energy transfer above and inside Antarctic blue ice. (Paper submitted for presentation at the 14th General Assembly of the International Association of Scientific Hydrology at Berne (Switzerland).)

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[A. 2498] S 1.25; 7/-2. (£ 0.35) (stg); 5 F

ERRATA

Page 11, column 2, lines 17-18. For In the rare 'catastrophic glacier advances ' read In the rare ' catastrophic glacier advances or surges'

Page 12, column 2 , lines 34-36. For and one expected to be achieved through 2,700 m of ice at Byrd, Antarctica, next summer) such precipitation data read and one through 2,200 m of ice at Byrd, Antarctica, in 1968), such precipitation data

Page 13, column 2, line 21. For 80° S. ( 40° W . , read 80° S., 40° E . ,

Page 15, column 2, line 14. For (Robin, 1966). read (Robin, 1966; Radok, Jcnssen and Budd, 1969).

Page 16, column 2:

(a) insert two references after Picciotto, E . 1962, as follows:

P I C C I O T T O , E . ; W I L G A I N , S . I963. Fission products in A n t ­arctic s n o w ; a reference level for measuring accumulation. J. geophys. Res., vol. 68, p . 59-65.

R A D O K , U . ; J E N S S E N , D . ; B U D D , W . F. 1969. Steady-state

temperature profiles in ice sheets. International symposium on Antarctic glaciological exploration, Hanover, USA. International Association of Scientific Hydrology.

(b) the last entry should read: W E L L E R , G . 1968. The annual heat energy transfer above and

inside Antarctic blue ice. Union de géodésie et géophysique internationale, Association internationale d'hydrologie scien­tifique. Assemblée générale de Berne, 1967. (Commission de neiges et glaces.) Rapports et discussions, p. 417-28.