Quaternary Glaciations - Extent and Chronology, Part III Editors J. Ehlers and P.L. Gibbard �9 2004 Elsevier B.V. All rights reserved

Landforms from the Quaternary glaciation of Papua New Guinea" an overview of ice extent during the Last Glacial Maximum

Jim A. Peterson ~ , S. Chandra ~ and Christian Lundberg 2

1School of Geography and Environmental Science, Monash University, Clayton, Victoria, Australia. Jim.Peterson@arts.monash. edu.au

:Department of Environmental Engineering, Lulea University of Technology, Christian.Lundberg@sb. luth.se

Abstract

Documentation of glacial landforms of Papua New Guinea is dominated by accounts of landscapes that are supported by chronologies assembled during biostratigraphical studies of peat cores showing that glacial landscape reconstruction will refer to the Last Glacial Stage. The steep terrain ensured that the scale of the air photographs used in these studies would vary all over the stereographic models formed for landscape interpretation. Here, in the form of annotated ortho-rectified (i.e. scale-consistent) satellite images, a summary of the maps found in the literature is presented, together with the results of simple spatial query designed to refine the accuracy of previously-estimated Last Glacial Maximum (LGM) ice extents.

Introduction

The legacy of Quaternary glaciation in Papua New Guinea has been documented in review (e.g. Hope & Peterson, 1975; Peterson et al., 2002) and in particular studies that date back eighty years or so (e.g. Detzner, 1921). Over that time, it has become clear that all mountains that were not too steep to retain snow cover, and were over 3700 m a.s.1. or so, now carry glacial remains, nearly all referable to the Last Glacial Stage. Scattered evidence for earlier stages has been documented during detailed field work (e.g. Dow, 1968; Blake & L6ffier, 1971; see Hope & Peterson, 1975) but the well- preserved glacial landforms, that dominate all the glaciated areas of New Guinea, have been widely dated as belonging to the Last Glacial Stage (cf. Peterson et al., 2002). The locations of the main glaciated areas are shown in Figure 1. Several other areas have been mentioned as having hosted very minor volumes of Quaternary glacial- stage ice: Mount Hagen (L6ffier, 1970; Bik, 1972) and Mount Kumbivera (L6ffier, 1971), Mount Mano and the Burger Mountains (Bik, 1971).

Characteristically, the (usually narrow) transition from erosional to depositional terrain is clearly marked, and the glacier-induced drainage disruption has left many lakes and bogs, the most strategically-placed of which have been cored to yield continuous stratigraphical records of post- glacier events. Landform interpretation in terms of glacial style indicates wet-based glaciers without permafrost.

The maps documenting the glacial terrain are displayed using the visible bands from rectified satellite image data. The landform overlays are from image interpretation 'ground-truthed' at various times by reference to accounts published by others.

Some of the Quaternary New Guinea glaciers were nourished by snow-beating winds from across the West Pacific Warm Pool and others from snow-bearing winds from across the Coral Sea or, of more relevance to glacial history in West Papua, across the Arafura Shelf. The latter area changed to a warm shallow sea of progressively greater extent during the Flandrian Transgression. This provoked late-glacial advances in the Moake Range of West Papua (Peterson & Hope, 1972) but not further east. In explanation, the steepness of the off-shore areas crossed by the SE Trade winds approaching Papua New Guinea ensured little change in the distance of the high tops to the sea in either direction, (cf. Galloway et al., 1973) whether the sea stood at interglacial high or glacial low level. To add further reasons why asynchronous mass-balance responses to the deglacial cycle might be expected:

some of the glaciated areas are known to be uplifting (Abbott et al., 1997) and,

one of the most interesting glaciated tops is a volcano (Mount Giluwe 4368 m a.s.l.) that has been active during the Quaternary, although apparently not so as to affect glacier mass-balance during the Last Glacial Stage. Thus the maximal extents mapped for this study are probably synchronous, but caution must be observed when attempting correlation of the youngest last glacial- stage retreat (as opposed to Neoglacial) moraines (clearly visible in many of the images) especially if the West Papuan retreat moraines are to be considered as well.

Previous workers have reported their interpretations with the aid of air photographs and maps derived there-from, but so far, overview that can be obtained from perusal of ortho- rectified (i.e. scale-consistent) satellite images has been somewhat lacking, here such satellite images and the results of simple spatial query referring to calculation of ice extents are presented.

313

314 Jim A. Peterson, S. Chandra &'Christian Lundberg

. . . . I I I

140 144 148

MT JAYA 4 , 8 8 4 m

above ~ 3.000m

2.000m

Kemabu P/ateau

MAOKE

ARAFURA

SEA

altitude

(SNow

IRIAN J A Y A

i I ~

I

I

I I I I i I

PACIFIC

Q

M T W I L H E L M 4 ,510m

MT GILUWE / ~ 04,368 m '9400 ~.,

PAPUA NEW GUINEA

OCEAN

q

Mt Albert Edward

0 km 300 c --__ - - - . . . . . ~ 1 4 0 1 4 4

. . . . . I ' '

Fig. 1. Location Map of the main Quaternary glacial areas of Papua New Guinea (after Hope & Peterson, 1975)

Imagery: sources and processing

Table 1 details the satellite imagery obtained from Geoscience Australia, and handled in ARCMAP so that the labels, cartographic symbols and legends could be added.

Table 1"

Mountain

Mount Wilhelm Mount Giluwe

Sarwaged

Mount Albert Edward Mount Victoria Star Mountains

Glaciated area krIl 2

65

187

73.4

84

Database queried

ARCGIS

ARCGIS

ARCGIS

ARCGIS

Previous estimate km 2

200

75

90

Reference

Blake L6ffier, 1972 L6ffier, 1971 L6ffier, 1970

17 ARCGIS 15 L6ffier, 1970

&

All images have been enhanced using contrast-stretching techniques.

LGM glacial zones

1. Mount Wilhelm (4510 m a.s.l.) LGM ELA 3550 m a.s.1.

This massif, the remains of a granodiorite batholith intruded by gabbro, is the highest mountain in Papua New Guinea. It carried a minor glacier during neoglacial times, and the depth of its valleys together with the extent to which glacial deposits can be found on their sides suggest that it is here that Quaternary ice was thickest.

Nevertheless, so dissected is this terrain that all glaciers were contained within valleys so very few interfluves were overridden. Thus many prominent ridges can be seen separating the glacial valleys with their characteristic suite of mountain landforms: mammilated surfaces in association with rock tams and rock-basin lakes (up to 60 m or so deep) , and beyond them, in the zone of glacial deposition, well preserved, sharp and voluminous moraines (Fig. 2).

Papua New Guinea 315

Fig. 2. SPOTIXS ortho-image K363-J362, 9 August 1997, of the Mount Wilhelm areas, overlain with an LGM boundary interpreted from the work of Hope & Peterson (eg 1975). The image clearly shows the forest edge, above which the ground-cover owes its distribution pattern not only to the altitudinal environmental gradient but also to burning off by local people. The glacial limits shown are generalised." clearly seen ridges have not been ice-smoothed but have been left un-annotated so that readers can interpret the boundaries for themselves. In the former accumulation zone, the limit has been drawn with a tendency to follow the distal borders of moraines. The yellow triangle marks the position of the summit (4510 m a.s.l.).

316 Jim A. Peterson, S. Chandra & Christian Lundberg

Fig. 3 (above). LANDSAT 5 ortho-image 98-64 6 Sept. 1997 of the Mount Giluwe area, overlain with an LGM boundary interpreted from the map published in Blake and L6ffler (1972). The trigonometry points on the mountain are marked by yellow triangles: 4368 m a.s.l. (western-most) and 4300 m a.s.l. The image clearly shows the forest edge above upper mountain mixed forest. Much of the ground-cover above the forest edge is a response to burning by local people.

Fig. 4 (upper right). Landsat 7 ETM ortho-image 95-66, 18 May 2002, showing Mount Victoria and environs. The yellow triangle indicates the approximate position of cloud-covered Mount Victoria (4036 m a.s.l.). The glaciated area is marked. Other slopes were high enough to support a positive mass balance but for the their steepness.

Fig. 5 (lower right). LANDSAT 7 ortho-image 96-66, 8 Sept. 2000, overlain with an LGM boundary interpreted from the map published by L6ffler (1970). The trigonometry points marking the position of Mount Albert Edward (East Dome) (3990 m a.s.l.) is represented by the yellow triangle. The image clearly shows the forest edge. Again, the pattern owes much to local hunting practice (including 'burning off') as to altitudinal environmental gradients.

Papua New Guinea 317

2. Mount Giluwe (4668 m a.s.l.) LGM ELA: 3550 m a.s.1.

Mount Giluwe (Fig. 3) is a dome-shaped volcano that has been active during the Quaternary but became dormant before the LGM (c f Blake & Lrffier, 1972). The outer ice limits of this stage define the area (187 km 2) occupied by an ice dome, outward from which ice flowed to form prominent terminal moraines, especially in the case of ice tongues reaching down to a maximum 3200-3500 m a.s.l., some of the more prominently incised radial drainage lines to reach their lowest levels down the more prominent of the many small valleys incised in the volcano flanks.

3. Owen Stanley Ranges (Mount Victoria (4036 m a.s.l.) and Mount Edward Albert (3996 m a.s.l.) LGM ELA: 3630 m a.s.1.

a) Mount Victoria: well-preserved moraines (medial, terminal and recessional) testify that two short valley LGM glaciers were present on the north-facing flanks of the north-west trending ridge west of the summit of this mountain (Fig. 4).

b) Mount Edward Albert, (3996 m a.s.1.) although a little lower than Mount Victoria (4036 m a.s.1.), was the more extensively glaciated of these two areas (Fig. 5). This illustrates the importance not only of elevation but also of suitability of topography to support snow accumu- lation.

4. Sarawaged Range (Mount Bangeta 4121 m a.s.l.) LGM ELA: 3650-3700 m a.s.1.

The glacial boundary mapped in Fig. 6 is after Lrffier (1971). Air-photographic interpretation was necessary because the published map was not at a scale convenient for transfer of the boundary to image overlay. Indeed, each air photograph varied greatly in scale as a consequence of the exaggerated height distortion in such rugged high relief terrain.

Two areas that seem to have supported glaciers at the LGM are distinguished.

The westernmost ('Uruwa Plateau') area is rugged with some higher parts reaching to 4000 m a.s.1. Lrffler (1970) distinguished about twenty cirques, none of which seem to have harboured glaciers large enough to have formed lakes, although evidence for short valley glaciers is mentioned in reference to the eastern Uruwa valley. The glaciated area estimate given in Table 1 includes 28 km 2 for the Urawa area. This ~s probably an inflated value because the cirque glacier extents, that comprise this estimate, are not assembled in as reproducible way as would be the case if the down-valley boundaries of all cirques were marked by obvious moraines.

Fig. 6. LANDSAT 7 ETM ortho-image 96-64, 14 Sept. 2002, overlain with an LGM boundary interpreted from the map published by Lrffler (1971). The trigonometry points on the mountain are marked by yellow triangles: 4180 m a.s.l. (western- most) and 3980 m a.s.l. The image clearly shows the forest edge, the position of which owes something to anthropogenic influences on vegetational communities.

The eastern area (Bangeta Plateau), depicted in Fig. 5, carried more and much thicker ice than did the Urawa area. Well developed and preserved glacial landforms are widespread enough for more significance to be assigned to contribution (45.4 km 2) of this area glaciated extent estimate that is given in Table 1.

5. Star Mountains (Mount Capella 4214 m a.s.l.) LGM ELA: 3460 m a.s.1.

The Star Mountains (Figs 7, 8 and 9) are found in high karst country adjacent to the international boundary between PNG and West Papua. At 4214 m a.s.l., in such a wet area, they would have to have been glaciated during the LGM if suitable terrain for snow accumulation existed. As seen from Figures 8 and 9, moraines are easily identified but the glaciers that left them behind were all remarkably small. What can be envisaged here is high budget wet-based ice formed from snow accumulating in high sheltered hollows below the regional snowline but above an orographic snowline, the latter raised by the presence of high volumes of (wet) snowfall. Unlike other mountain areas of New Guinea, the Star Mountains are not 'robbed' of moisture by other moutain ranges, either to the north or to the south. The high precipitation totals here reflect this. All year will

318 Jim A. Peterson, S. Chandra & Christian Lundberg

Fig 7. LANDSAT 7 ETM ortho-image 100-64, 8 January, 2000, overlain with boundaries of the areas depicted in more detail in Figures 7 (the NW box) and 8 (the SE box). These latter were rectified and sub-setted from air photographs taken in 1963. The spot height marked with a yellow triangle represents an isolated prominence of known height (3123 m a.s.l.). The cleared area shown in this image represents the Ok Tedi mining area. The 'snap-shops'represented in Figures 7 and 8 refer to a time before the mining development.

Fig. 9. Geo-referenced clipped sub-set of scanned data from Air Photo CAJ.172-5079." New Guinea Border," North Coast-Fly River, Run 1A 26/1/63. The distribution of moraines and rock basins indicate the presence of small LGM glaciers in the Star Mountains. Limestone peaks drain mostly underground, and so even small moraines on steep slopes have been preserved, despite the very high all-year rainfall (annual average 8000 ram) in this area. Some of the glaciers clung to steep lee-side slopes and reached surprisingly far down the mountain sides, pointing to the mass-balance advantage such ice bodies have when climatic deterioration brings a threshold increase in snow percentage in an area of high precipitation. Surface water can exist in these areas because the glaciers were high budget ice bodies grinding enough rock flour (found at the base of lake and swamp-bottom cores ) to block the drainage fissured eroded by solution weathering in pre-glacial and interglacial times. The image also shows that other ice bodies formed in rubble-filled sink holes on the higher ridges.

be wet because both the SE and the NW monsoon will bring moisture. In such a circumstance, it would be expected that the glaciers would not have a preferred aspect. However, most face south because the north-facing slopes of the Star Mountains are unrelentingly steep.

Slope declivity has been crucial in determining sites of snow accumulation. Many of the highest and smallest snow-gathering hollows were formed by solution weathering in pre-glacial times.

Fig. 8. The other geo-referenced clipped sub-set of scanned data from Air Photo CAJ. 172-5079: New Guinea Border," North Coast- Fly River, Run 1A 26/1/63. (see SE box, Figure 6). Many of the same remarks that that have been made concerning the terrain depicted in figure 7 can be applied to the terrain imaged in this figure. Natural snow-fence orientation in the area shown by the northern part of this image ensured received snow from lee-side accumulation all year. Not surprisingly, the glacier was longer than others that formed in the area shown here, reaching down to about 3200 m a.s.l.

Concluding remarks

It is clear that ortho-rectified satellite images can be used to document Quaternary glacial extent if the glacial modification of terrain has been sufficiently obvious. The approach used here allows uncertainty is estimates obtained with the used of uncontrolled air photograph mosaics to be tested, and can be extended to include the use of the ortho- images for rectification of selected air photographs. This

Papua New Guinea 319

latter approach is attractive for documenting landscape evolution where glacial terrain modification is subdued. It is worth noting that the satellite image archive is now voluminous enough for the chances of cloud-free image purchase, even for areas with cloudy climates, to be probable. The oldest satellite image used in this report was from 1994, and all the rest refer to 'snap-shots' dating from later than July 1997. There is much further scope for deployment of this approach to mapping glacial landforms. Further work on the evolution of landscape in the highlands of Papua New Guinea will focus on the areas for which very small glacial modification has been claimed.

A.P., David, B., Tapper, N.J, Penny, D. & Brown, J. (eds), Bridging Wallace's Line." the environmental and cultural history and dynamics of the SE-Asian-Australian Region. Advances in GeoEcology, 34, 360 pp.

Acknowledgement

The work reported here is part of work supported by the Australian Research Council (Grant A39801047). We would like to thank Professor Dr E Lfffler for the loan of air photographs and for helpful advice."

References

Abbott, L.D. Silver, E.A., Anderson, R.S., Smith, R.; Ingle, J.C, King, S.A. Haig, D., Small, E., Galewsky, J. & Silter, W. (1997). Measurement of tectonic surface uplift rate in a young collisional mountain belt. Nature, 385, 501-507.

Blake, D.H. & L6ffler, E. (1971). Volcanic and glacial landforms on Mount Giluwe, Territory of Papua and New Guinea, Geological Society of America Bulletin, 82, 1605-1614

Detzner, H. (1921). Vier Jahre unter Kannibalen. Scherl, Berlin, 338 pp.

Dow, D.B. (1968). A geological reconnaissance in the Nassau Range, West new Guinea. Geologie en Mijnbouw, 47, 37-46

Galloway R W, Hope, G.S., L6ffler, E. & Peterson, J.A. (1973). Late Quaternary glaciation and periglacial phemonena in Australia and New Guinea. ln: van Zinderen Bakker, E.M. (ed.) Palaeoecology of Africa and Antarctica, 8. 125-138. Cape Town, Balkema.

L6ffler, E. (1970). Evidence of Pleistocene glaciation in East Papua. Australian Geographical Studies, 8, 16-26

L6ffler, E. (1971). The Pleistocene glaciation of the Saru- waged Range, Territory of Papua New Guinea. The Australian Geographer, XI (5), 463-472.

Peterson, J.A. & Hope, G.S. (1972). Lower Limit and Maxi- mum Age for the Last Major Advance of the Carstensz Glaciers, West Irian. Nature, 240, 36-37.

Hope, G.S. & Peterson, J.A. (1975). Glaciation and Vege- tation in the High New Guinea Mountains, Bulletin of the Royal Society of New Zealand, 13, 155-162.

Peterson, J.A., Hope, G.S., Prentice, M. & Wahyoe Hantoro (2002). Mountain environments in New Guinea and the late Glacial Maximum 'warm seas/cold mountains' enig- ma in the West Pacific Warm Pool region, ln." Kershaw,