ice-marginal debris-flow deposits in western allgau, southern west germany

Ice-marginal debris-flow deposits in western Allgau, southern West Germany MATG.G. DE JONG AND MARTIN RAPPOL

Jong, Mat G . G . Dc & Rappol, Martin lYX30301: Ice-marginal dchris-flow deposits in wcstcrn Allgdu.

Icc-marginal debris-flow dcposits (comparahlc to deposits clscwhcrc dcscrihcd as flow t i l l \ ) are dcscrihcd from glacier-proximal sediments in an Alpine foreland area. Dchris-flow deposits arc chariictcristically interstratified with auhacric or suhaquatic meltwater deposits. and occur in a wide variety of geomorphological settings. The granulomctric composition of debris-flow deposits is more variahlc than that of subglacial tills. Within-flow variability may occur as a result of the formation of gwdcd hcdding. lateral as well as vcrtical. Clast flihrics show hoth random and preferred orientations; unequivocal interpretation of these is not possihlc. Dchris-flow deposits arc composed of metcri;il derived from various source%: sources from suhglacially-derived dchris a s well iis from previously deposited tills and watcrlain sediment\ can he dcmonstratcd.

Mut De Joiig uiid Murriir Ricppol. LohorutorJ for Pliy.siccc1 Geogriipli~ ccnd Soil .kieirc.e. Utiiiwsit! of Ainsterduin. Dapper.srrcicir I I S . /OY3 8.5 Arnstertluin. The Nerlierlnrids; 12th Frhrurirv. 19x2.

BOREAS southcrn west Germany. Boreus. VOI. 12. pp. 57-70. OSIO. ISSN 03WY4X3.

During the past decades a number of papers have been published on a sediment-type commonly mentioned flow till, referring to a sediment formed as a result of mass movement of glacial debris or till, normally under conditions of high water content. Although this phenomenon had been recognized before, it was Boulton (1968. 1971, 1972) who elaborated the concept from studies at modern glaciers of Svalbard, and recognized its stratigraphic significance when ap- plied in the areas of Pleistocene glaciations. Since this time, flow tills have been reported from many formerly glaciated areas and several types have been distinguished (e.g. Marcussen 1973; Evenson et al. 1977; May 1977; Eyles 1979; Stankowski 1980; Hicock et al. 1981). From the Alpine foreland, Van der Meer (1979) described complex till sections that were tentatively interpreted as flow tills. De Jong et af. (1982) describe an occurrence of flow till at Mehetsweiler in western Allgau.

The use of the term flow till was opposed by Lawson (1979), who argued that resedimentation processes at the glacier margin destroy the glacigenic character of till deposits and impose their own structural and textural characteristics upon them. Lawson (1979, 1981) distinguished several types of sediment flows. Likewise, Rappol (1979) preferred till-flow deposit as a specified variation on debris-flow deposit. Recently, Boulton (1980) stressed that for flow tills flow should be glacially-induced.

When dealing with Pleistocene sediments we prefer the use of a neutral term, as it will often be very difficult or impossible to indicate wheth- er flow was glacially-induced or not, and to speci- fy the source of the material. Moreover, as it is common practice to consider till as a sediment deposited directly by a glacier without subse- quent reworking by meltwater, it seems only logical to exclude for till also redeposition by mass-movement processes. Following these con- siderations we prefer a process-oriented termin- ology and terms in common use in sedimento- logy. Flow of a variable amount of clasts sus- pended in a mixture of fines and water is called debris flow, and the resulting diamicton a debris- flow deposit. Fine-grained varieties, containing over 50 % silt + clay, are generally called mud- flow deposit.

The aim of this paper is to demonstrate the occurrence of debris-flow deposits in the sediment complexes of Pleistocene ice-marginal environments of western Allgau; to show their variability in structural and textural characteristics; to give some indications about the source of the material; to discuss mechanisms of transport and sedimentation.

The preglacial bedrock of the investigated area is formed by Tertiary rocks consisting of calcare- ous shales, sandstones and conglomerates (Mo- lasse). Glacier movement was predominantly di- rected by the structurally controlled relief of the Molasse rocks (Fig. 1). Regional analysis has

5 - Boreas 1/83

58 Mat G. G . De Jong and Martin Rappol BOREAS 12 (1983)

Fig. 1 . Location map with topographic names mentioned in thc tcxt. Arrows givc main directions of glacier movemcnt during Wiirmian glaciation

been given by Kraus et al. (1932), Schmid (1954, German (1976), Kruse (1979). Rappol (1979), De Jong (1980) and Keller & Krayss (1980), among others.

Geomorphological setting and sedimentological description of outcrop sections Grenis. - The Grenis pit is excavated in a north- sloping terrain which forms part of an elongated belt of coalescing fans of outwash deposits. The fan head zone ends abruptly with a steep slope to the south; one can speak of an Endmoranenver- treter (Gripp 1975). Especially the proximal part is kettled; some kettles contain water. Evidence of melting of buried ice was also found at two

places in the southern pit face, showing collapse structures which correspond with surface depres- sions.

Exposed are subhorizontally layered, domi- nantly coarse-grained, tabular beds with only sporadic shallow erosional contacts. Interstrati- fied with these waterlaid beds are diamict layers and occasional gravelly or silty sand layers. In general the sedimentary sequence indicates a gradual building up of the sediment body. Only one important erosional contact, marked by a concave bouldery lag forming the base of a 10 m deep gully, was found in the upper middle part of the southern pit face.

The pit has previously been described briefly by Weinhold (1973), who mentions the occurrence of three Grundmorane layers that should represent glacier oscillations. Since his investiga- tions, the pit has been enlarged considerably.

BOREAS 12 (1983) Ice-marginal debris-flow deposits 59

Diamict. till-like layers are found all along the southern and southeastern pit faces, especially in the upper parts. In the northwest part of the pit, i.e. a more distal part of the outwash slope, diamict layers are notably absent and glaciofluvial sediments are better sorted and have a smaller maximum clast size.

The diamict layers are regularly interbedded with the waterlaid deposits and no structures resulting from pushing or shearing by glacier ice have been observed at their base (Fig. 2). They are interpreted as debris-flow deposits. which also finds support in the presence of lateral as well as vertical grading in some of the layers, and the nature of the erosional lower bed boundaries (Figs. 3 and 4).

Lithological composition of samples from debris-flow deposits and glaciofluvial sediments (Table 1) gives no indication of differentiation of source material for the sediment types.

Figs. 2 and 3 also give clast fabric diagrams from the debris-flow deposits. The diagrams show poorly developed preferred orientations compared with stone orientations in subglacial tills. Imbrication patterns in stream-flow deposits

2 a N 2b N

F i g 2. Alternating watcrlaid and debris-flow dcposits in south- castcrn part of the Grenis pit. A bouldcr-supportcd deposit of uncertain genesis, tentatively rcfcrrcd to as ablation complex. ovcrlics the scqucncc. Rosc diagrams givc clast orientation in debris-flow deposits: la and 2a - long-axis orientation; Ib and 2b - alb-plane dip direction. Lcgcnd also applics to Figs. 3. H, 10. 11.

are given in Fig. 5. Main flow direction of debris flows is considered to be more or less the same (see further 'Discussion').

Fig. 6 gives the grain-size distribution of samples from debris-flow deposits at Grenis. I t ap- pears that there is a large variation in grain-size composition, which is mainly caused by variations in the gravel content.

The general nature of sediment-type distribution in the Grenis pit is in many respects similar to that of alluvial-fan sediments as described e.g. by Hooke (1967). Bull (1977) and Wasson (1977). A remarkable difference. however, is the absence of stream-flow gully features. This may be due to the absence of a fixed apex point indicating that in this ice-marginal environment, different from alluvial-fan environments, the main streams are not confined between valley walls before entering the fan area.

Au. - The pit at Au is excavated in an originally about 15 m high, SSW-NNE trending small hill forming part of a landscape with irregular topography along the southern fringe of a terrace near Kisslegg (655 m above sea level). According to

60 Mat G . G . De Jong and Martin Rappol BOREAS 12 (1983)

SE NW

1 2 3m scale

Fig. 3. Section from the south pit face showing erosional lower hed houndary of two dehris- flow drposits and coarse fraction grading in vcrti- cil and lateral directions. See also Fig. 4. Lcgcnd and diagrams as in Fig. 2.

3b N

@ n,31

5a N

@& n,51

n=25

Fig. 4. Detail of central part of Fig. 3. showing coarse-grained gully fill (A) and grading (e.g. at B). Ruler ( I m) is held at the contact between upper and lower heds.

BOREAS 12 (1983)

c

d f d

g fd

g f d

d f d

ac

g f d

d f d

5 t

s t

s t

g fd

d f d

d fd

d f d

d f d

d f d

dfd

Ice-marginal debris-flow deposits 61

$ ? z m

- 0 L

E i B S v ) z

300

300

300

300

300

300

300

214

231

265

300

300

251

280

300

300

300

N N

Fig. 5. Imbrication of alh-planes in waterlaid deposits from proximal (I. 11) and distal (111. IV) sites at Grciii\.

German (1967, 1976). the terrace consists of sediments that have gradually filled in a large ice- dammed lake that existed in front of the S re- treating Rhine-glacier at the end of the Wiirm Ice Age. The hummocky topography is the result of melting of buried ice present in the proximal part of the sediments of the terrace. Deforma- tion structures in the pit comprise tilted and warped beds with inclinations up to 70".

Fig. 7 shows part of the southeast part of the pit. A.regular alternation of sand beds, cobble- supported beds and diamict beds is exposed. The diamict beds show variable sorting of the matrix, sometimes weak layering and grading in the coarse fraction. They are interpreted as debris- flow layers. Also the lateral extension of layer 7 (Fig. 7) towards north-northeast showed alternating thinly bedded diamictons and sand layers in a regular sequence.

Lithological composition of one debris-flow layer and the cobble-supported sediment (Table 1) is considered to be not significantly different (De Jong 1980). Also, the difference between Grenis and Au samples probably reflects a normal variation in composition of the source material.

Steinegaden. - The Steinegaden gravel pits are excavated in a large ridge consisting of unconsolidated materials with an intricate stratigraphy, formed in an interlobate position between the so- called Argen and Rotach lobes of the Wiirmian Rhine glacier (Ziegler 1976; Kruse 1979). The ridge formed part of an important drainage net- work during Wiirmian deglaciation (Kruse 1979).

Table 1 . Lithological composition of the fraction S-X mm for some of the described sediments. Difference hetwccn Grenis/ A u and Stcincgaden/Ellhofcn in the percentages of the 'igneous and metamorphic' group i s a characteristic feature of thc compositional diffcrencc hetwccn Argcn- rcsp. Rotach-lohc. dfd = dehris-flow deposit: gfd = glaciofluvial dcposit: st = huh- glacial till: ac = ahlation complex

0 c

u 0 J

- G R E N I 5

- A U

- S T E I N E G A 0 E N

- E L L ii

-

The ridge is predominantly built up of meltwater sediments formed during several phases of deposition. This is demonstrated by the presence of erosive contacts and subglacial till layers. Fig. 8 shows a sedimentary sequence in the easternmost gravel pit, near the steep eastern flank of the ridge. The lowermost part of the exposed section shows well-sorted coarse- grained sand and gravel beds in a disturbed position. Separated by an erosive contact these are overlain by moderately to well-sorted coarse- grained glaciofluvial gravels, with large-scale trough stratification. Some troughs consist of

62 Mat G. G. De Jong and Martin Rappol

b l

7 0

50 --

30 - -

I I I 1 - I 1

3 2 1 0 1 2 3 4 5

bouldary lag deposits. Occasional diamictons with sandy matrices are present. This deposit is covered by approximately 2 m of glaciolacustrine silts and fine sands, which in the upper part contain abundant diamict layers. The sequence further shows a gradual coarsening upward and becomes bouldery at the top. This upper part of the sequence is interpreted as an ablation complex with subaeric as well as subaquatic debris- flow deposits. Grain-size distributions of the debris-flow deposits are highly variable. They may

6

BOREAS 12 (1083)

Fig. 6. Cumulative frcqucncc curves of 13 grain-size samples of debris-flow deoosits from rhe

. , I

7 8 9 0 Grcnispit.

be massive or graded (Fig. 9). Some subaquatic debris-flow deposits contain silt pebbles,

In directions south and west of the sequence shown in Fig. 8, it has been observed that the ablation complex was deformed, showing inclinations of layers in a southwest direction and in- tense block-faulting with cumulative displace- ments of over 5 m. Although pushing phenomena have been observed on a small scale, deformation is predominantly the result of melting of buried bodies of dead ice.

- Fig 7 Part of the exposure at Au I - well-sorted gravel. I1 - laminated rand. 111 - massivc sand. IV - essentially mdssivc dehri\- flow deposit with textural banding, V - debris-flow deposit with bouldcry hasc and composed of sevcrdl thin layer*. VI - dchris- flow dcposit which Idlerally chdnges into waterlaid gravels. VII - thinly bedded sand/silt deposit. Vll l - dominmtly cohhlc- supported gravel with occasional sand layers Arable numbers give dip direction dnd inclination of hcds


SE NW soil

b Fig. 8. Sedimentary bcqucncc of the upper castcrn part of the southeast pit at Stcinc- gadcn. Compilation of data of 1979. 19x0 and 1481 surveys. Scale in metre\. Lcgcnd as in Fig. 2. For explanation scc text. R~~~ diagram oricnt;,tion ,,[ e~on-

clasts i n a suhaqu;,tic dcbri,-now deposit.

Fig. 9. Detail of suhaquatic dchris-flow dcpobih at Stcincga- den. showing massive and griidcd layers.

Subglacial till is present in the wall opposite that described in Fig. 8. Also, in a pit some 100 m to the South a strongly dipping subglacial till layer was present. The relation between this subglacial till and the ice-marginal sediments is not clear, however. Lithological composition of subglacial till and debris-flow deposits (Table 1 ) is much alike. The low percentages of 'igneous and metamorphic rocks', as compared with those of samples from Grenis and Au, is characteristic of deposits of the Rotach-lobe at the eastern flank of the Rhineglacier. Unusual, however, is the extremely high amount of locally-derived Mo- lasse clasts. Consequently, this high amount of Molasse components in the debris-flow deposits

must be the result of resedimentation of subglacially-derived debris that was brought by the glacier to its margin. Decrease in the amount of Molasse sandstone in the glaciofluvial sediments will be partly the result of low resistance of this rock type against meltwater abrasion.

Ellhofen. - Near Ellhofen, gravel pits are excavated in ice-marginal stream terraces which were built up at approximately the same time as the Steinegaden ridge. The terraces lie on the eastern side of the Rotach valley. Three levels are present which are flanked at the glacier side by up to 15 m high, south-southwest-north-northwest trending ridges (Ziegler 1976; Kruse 1979).


Fig. 11. Debris-flow layers intcrstratificd with laminatcd silts. exposed in a small morainc ridgc cnclosing a cirque wcst of thc lmmcnstadtcr Horn. A = gradcd finc-grained dchris-flow dcposit; B = massive coarse-grdincd dchris-flow dcposit (sample 970 in Fig. 14); C = gradcd finc-graincd dcbris-flow dcposit (samplc 971 in Fig. 14).

steep slopes, covered with previously deposited glacial sediments extend above the glacier. With the thinning of the glacier, these tills may be- come unstable, move downslope and come to rest at the lowered glacier flank.

In this context we mention some observations made in 1979 along the southern flank of the Aletschgletscher (Switzerland), at a locality called Silbersand (Landeskarte der Schweiz 1:25,000, Blatt 1269 Aletschgletscher). The glacier is debris-free, apart from a single grain layer of angular boulders and dust at its surface. The

Fig. 12. Mass-movcmcnt phenomena in a scdimcntary scqucncc of the ice-lakc dcposit south of Konstancc. Alpscc vallcy. I . I I - synscdimcntary deformation. A - liqucficd flow associatcd with deposition of dchris flow B.

bulk of the material present at the glacier flank, with an abundance of fines and rounded stones, appeared to be derived from the till-covered slope above the glacier by way of mass movement processes. Last-winter snow was found interstratified with debris-flow deposits. Deforma-

66 Mar G. G . De Jong and Martin Rappol BOREAS I2 (1983)

slope dmposit

s i l t and sand

linm-gr. debris-(low d.

silt

grovel

laminated s i l t with slump structures

coarse poorly-sortmd pravml

massive line-groinmd debris-flow deposit

gravel

sand

mossive sandy s i l t

well-sorted gravels with s i l t layers

cobblms in well-sort*d silty motr i i

debris-flow deposit with inclusions

laminated si l t

l ine grovel

tion of mass-movement products results from snow melt, ice-core ablation and glacier pushing. Activity of flowing water is restricted to sedimentation of lenses of sorted material in sediment traps between hummocks. The preservation po- tential of such complex sediment associations is low, however, because of the constant reworking and the presence of steep slopes. In the Alpsee valley favourable conditions existed because of the presence of relatively large ice-lakes between glacier and valley slope.

These observations are significant in another sense, as they provide one way of explaining the presence of abundant subglacially-derived material in ice-marginal deposits in areas of high relief.

Upper Weissach valley. - In the Upper Weissach valley, at the junction of Weissach and Lanzen- bach, a sequence of silty and gravelly deposits and interstratified debris-flow layers is present. much similar to that described from the Alpsee valley. The Upper Weissach valley was probably not reached by Rhine- or Iller-glacier lobes during the last glaciation, but was partly occupied by local glaciers descending from the Hochgrat range.

Fig. 13 shows a sequence recprded in a road cut, and which is underlain by a subglacial till that was exposed in other sections. It concerns proglacially deposited sediments, probably formed in an ice-dammed lake that resulted from blockage of the Upper Weissach near Oberstau- fen by a lobe of the Rhine-glacier system moving through the Lower Weissach valley in an east- northeast direction. The debris-flow deposits show again a large variation in texture. Some of the silty deposits are massive and contain occasional clasts; these represent highly fluidal flows with truncation of the coarse fraction (Fig. 14: sample 45, also sample 971 from the Alpsee valley). Although such deposits are not easily con- fused with subglacial tills, it demonstrates the textural variability of debris-flow deposits and the necessity of a clear terminological distinction between glacigenic till deposits and resedimentation products.

Discussion and conclusions Debris-flow deposits are a widespread feature of

They are found in association with various sedi- Fig. 13. Sedimentary sequence in the upper Wcissiich valley. See the ice-marginal sediments Of Allgall. text. Scale in metrcs.

BOREAS 12 (1983)

90

lo--

50

30

lo

Ice-marginal debris-flow deposits 67

--

.-

- -

..

Fig. 14. Cumulative frequency curvcs of grain-size composition of dcbris-flow dcposits dominated by Molassc-derived material from Alpscc. Stcincgadcn and Weissach sitcs. Concave middle sections arc characteristic of Mo- law-derived tills and thcir resc- dimcntation products.

%

__/ .& 1- 1 1 1 1 1 1 1 1 I 1 I I I 3 -2 1 0 1 2 3 4 5 6 7 8 9 0

ment types, formed both in subaeric and subaquatic environments, and they occur in a number of different geomorphological settings.

Many factors promote mass movement in ice- marginal environments: the presence of a relief that is subject to quick changes as a result of the dynamic environmental conditions provided by the (active) glacier and high-energy fluvial ac- tion; the absence of vegetation; the abundance of unconsolidated material, often containing a large amount of mud; periodically changing quantities of water in the fluid phase. The depositional environmental conditions promote the formation of multiple sortedhon-sorted sediment se- quences. Depositional conditions may be similar to those of the supraglacial morainic till complexes of Eyles (1979).

The source material may be different from place to place. At Steinegaden, it can be con- cluded that subglacially-derived debris, mainly of local origin, was brought to the glacier margin. where it became subject to resedimentation by mass movement. Some debris-flow deposits in the Alpsee Valley show evidence of resedimentation of previously deposited subglacial till along the valley slope. At Ellhofen debris-flow deposits are predominantly derived from supraglacial materials and the local influence seems to be less. At Grenis, diamictons are characteristically inti- mately related to the glaciofluvial sediments in which they occur. showing affinity to alluvial-fan

sediments; their common source must be the glacial debris.

Gruin-size

Grain-size distribution of debris-flow deposits has been determined for 37 samples from the described outcrop sections. Bulk samples of about 2 kg each have been taken, allowing deter- mination of the fractions up to - 4 0. Fractions smaller than 4 0 have been determined by pi- pette method, larger fractions by dry sieving. Because of the high content of primary calcare- ous grains (generally over 60 96) samples have not been decalcified. Grain-size parameters have been determined for the matrix (smaller than - 10) following the graphic method of Folk & Ward (1957). Grain-size composition of glacial diamictons will be discussed in more detail by Rappol (in prep.).

Fig. 15 gives a plot of mean size (Mz) versus standard deviation (QDi, a measure for sorting) for the debris-flow samples and 24 subglacial till samples from the same area. I t shows a large variation in mean size for the debris-flow deposits, while the samples from Grenis are seen as a distinct group because of poorer sorting. Fine- grained samples on the right-hand side of the diagram are all subaquatic debris-flow deposits. Compared to subglacial tills, debris-flow deposits show a larger variability for all four Folk & Ward

68 Mar G . G . De Jong and Martin Rappol BOREAS 12 (1983)

0 4

QDI 3

'\A A'

"."II, l lf* d."",,!,

D"I.l,.I ,.I,

3 4 5 8 O Mz

Fig. I S . Plot of mean sizc versus inclusive graphic standard deviation of dchris-flow deposits from Mchctawcilcr. Alpscc vallcy. Stcincgadcn. Au. Ellhofcn and Wcissach vallcy and suhglacial tills from the slime region.

grain-size parameters - most significantly in mean size, where they show a distinct coarse- grained subpopulation.

The form of the cumulative frequence curves is governed mainly by regional variation in the composition of source material (compare Figs. 6 and 14). Sediments dominated by Molasse-derived material (Table 1) show a characteristic concave middle section. The absence of this in the Grenis-samples explains their poorer sorting. Local variability in grain-size occurs as a result of processes related to flow mechanism, e.g. formation of graded bedding. coarse fraction truncation and loss of fines.

Clast fabric Information on clast orientation in debris-flow deposits is scarce, which makes interpretation of our data difficult. Lindsay (1968) presents a com- puter simulation model of elongated clast orientation in mudflows, producing well-developed preferred orientations parallel to flow. Boulton (1971) gives stone orientations in lobate flow tills on Svalbard, with long-axes orientations parallel to main flow direction. Marcussen (1975) states that orientations in flow till are poorly developed. Enos (1977) mentions both random and preferred clast orientations and suggests that the latter are produced in muddy deposits by laminar

flow. According to Lawson (1Y79. 1981) pebble fabric in sediment-flow deposits is absent or poorly developed. De Jong et al. (1982) give two diagrams from Mehetsweiler (Fig. 1 ) showing non-random orientations in deposits in western Allgau. This information suggests that a crude parallelism of a-axes of elongated stones with flow direction can be expected, except in the distal part of the flow lobe. Preferred orientations are generally less well-developed than in subglacial tills.

Fig. 5 gives four diagrams of stone imbrica- tions in the meltwater deposits of Grenis. The flow direction varied between north-northeast and west Weinhold (1973) observed a downfan change in direction from north to west, but he presents no quantitative data. It can be supposed that the main flow direction of debris flows lies between north-northeast and west. Figs. 2b and 3b give diagrams of clast fabric in debris-flow deposits at Grenis. Both random and preferred orientations occur. A-axes orientations are weakly developed. Combination of a-axes and a/ b-planes diagrams does not exclude transverse orientations of some of the long-axes fabrics. Fabrics from Mehetsweiler (De Jong el al. 1982) and Steinegaden (Fig. 8b) show a relation between dip direction and slope.

The presence of preferred orientations of clasts suggests laminar flow, while the erosive


lower boundary of some of the debris-flow beds at Grenis indicates turbulent flow. This contra- diction can be explained as follows: laminar flow existed during final stage of flow with decreasing velocities and after a period of erosive turbulent flow (Lindsay 1968; Enos 1977).

Epilogue The recognition of mass-movement processes be- ing responsible for resedimentation of glacial debris and till is of great importance both for environmental reconstruction and stratigraphical in- vestigations. We realize that it will be hardly possible to give unequivocal criteria for distinguishing between glacigenic till deposits and resedimentation products. However, based on our own observations and those presented in the lit- erature, we suggest that the following features are strongly indicative, especially when present in combination, of a debris-flow origin of certain deposits:

a repeated interstratification of diamictons and waterlaid sediments in a geomorphological setting indicating a former ice margin; sedimentary features grading, especially in the coarse fraction, in vertical and lateral directions; flat upper bed limits and gully-like erosive,lower bed limits; absence of shear structures, e.g. low angle shear planes, at the base of the diamicton, characteristic of subglacial deformation under conditions of high normal pressure (glacier load); a high variability in clast orientation within and between site; a high variability in grain-size characteristics within and between layers.

Acknowledgemenrs. - We arc grateful to G. C . Maarlcvcld and J . Rupkc for their critical readings of the manuscript. Wc would likc to thank thc following persons for their assistance and discussions i n the field: W. den Bestcn. F. Knaack and J . Rupkc. A. Koning and M. dc Vri. draftcd the figures. Photo- graphic assistance was given hy H. van Maren.

References Badcr, K. & Jerz. H . 197X: Dic glaziale Uherticfung im Iller-

und Alpscctal (Ohcrcs Allgiu). Geol. Jh. AJ6. 25-45. Boulton, G. S. IYM: Flow t i l ls and related dcposits on somc

Vcstspitshcrgcn glaciers. 1. Gluciol. 7. 39 1-412. Boulton. G. S. 1971: Till genesis and fabric in Svalhard. Spits-

hergen. In Goldthwait. R. P. (ed.): Ell, u Svmposium. 41- 72. Ohio State Univ. Prcss. Columbus.

Boulton. G . S. 1972: Modern arctic glacicrs as depositional

models for former ice shccts. J . Geol. Soc. Lond. 128, 361- 393.

Boulton, G . S. 1980: Classification of til l. Quurern. N e d . 3 1 . 1-12,

Bull. W. B. 1077: The alluvial-fan environment. Prugr. PIty.s. Geogr. 1. 222-270.

Enos. P. 1977: Flow regimes in dchris flows. Sedimertrulug.~ 24. 1 3 f 142.

Evenson. E. B., Drcimanis, A . & Newsomc. J. W. 1977: Suhaquatic flow ti l l : a new interpretation for the genesis of somc laminated t i l l deposits. Boreus 6. 115-133.

Eylcs. N. 1979: Facies of supr;iglacial sedimentation on Icc- landic and Alpine temperate glaciers. Cun. J . Eurrh Sci. 16. I34 I- I36 I .

Folk. R. L. & Ward. W. C. lY57: Brazos River Bar: A study in the significance of grain-size parameters. J . Sedimenr. Perrul. 27, S26.

German. R. 1967: Landsch;iftsgcschichtc dcr Karhech-Eis- zunge. Sondcrdruck iius Narur.sihurz Oher.schk.uhett-Boden- see-Heguu 8. 5 pp.

German. R. 1976: Landschaft und Natur. Gcographic und Geologic. Sondcrdruck aus Der Kreis Rwenshurg. S3 pp. Konrad Thciss Verlag. Sluttgart und Aalcn.

Gripp. K . 197.5: Hochsandcr-Satzmoriinc-Endmo~~ncnvcr- trctcr. Z. Geomorph. N. I.: 19. 49(L496.

Hicock. S. R.. Dreimanis. A. & Brostcr. B. E. 19x1: Suhma- rinc flow t i l ls at Victoria. British Columbia. Cun. J . Eurrli sci. 18. 71-xo.

Hooke. R. Lch. 1967: Proccsscs on arid-region alluvial fans. 1. Geol. 75. 43K-464.

Jong. M. G. G . Dc 19x0: Gcornorfologisch en sedimcntologirch ondcrzoek in ccn gchicd rondom Wangcn im Allgiiu. Zuid- Duitsland. 95 pp. M . Sc. Thesis. Univ. of Amsterdam (unpublished).

Jong, M. G. G . Dc. Rappol, M. & Rupkc. J. 19x2: Scdimento- logy and gcomorphology of drumlins in western Allgju. South Germany. Boreas / I . 37-45.

Kcllcr. 0. & KraySS. E. 19x0: Die Ictztc Vorlandvcreiwng in der Nordostschwciz und im Bodcnsee-Raum (Stadialer Komplcx Wurm-Stein am Rhcin). Eclogue gcol. Helv. 7.V.7, X2S838.

Kraus. E. el d. 1932: Erliutcrungcn zur gcologischcn Ausgahe dcs Blattcs MI Kcmptcn dcs Dcutschen Rcichcs I : IONOIW). N. Jh. Min. err. 69. Bed. Bd. Ah!. B. IXY-36.

Krusc. G. A. M. 1979: A sedimcntological and gcomorphologi- cal study of the contact arca of the Weiszach. Rotach and Argcn Wiirmian glacier lohes (Badcn-Wurttcmhcrg. Bayern. Gcrman Federal Rcpuhlic). X7 pp. M.Sc. Thesis. Univ. of Amsterdam (unpublished).

Lawson. D. E. 1979: Scdimcntological analysis of the western tcrminus region of the Matanuska Glacier. Alaska. CRREL Reporr 79-9. 1 I 2 pp.

Lawson, D. E. 1981: Distinguishing Characteristics of diamictons at thc margin of the Matanuska Glacier, Alaska. Ann. Glaciology 2. 7844.

Lindsay, J. F. 196X: The dcvclopmcnt o f clast fahric in mudflows. 1. Sedimenr. Petrol. 38. 1242- 1253.

Marcusscn, I . 1973: Studies on flow till in Denmark. Roreirr 2. 21S231.

Marcusscn, I. 1975: Distinguishing hctwccn lodgcmcnt till and flow till in Denmark. Boreas 4. 11S123.

May. R. W. 1977: Facics modcl for sedimentation in the glacio- lacustrinc cnvironmcnt. Boreus 6. 1 7 S l X O .

Mecr, J. J. M. van dcr 1979: Complex till sections in the western Swiss Plain. In Schluchtcr. Ch. (cd.): Moruines and Vurut-s. 26-S269. Balkema. Rottcrdam.

Rappol, M. 1979: On thc glacial geology and morphology of

I0 Mar C . G . De Jong and Martin Rappol BOREAS 12 (1983)

the Subalpine Molassc region in wcstcrn Allgdu. southern Germany. 154 pp. MSc. Thesis. Univ. of Amsterdam (unpublished).

Stankowski. W. 1980: The structural heterogcncity of Wiirm flow ti l ls and melt-out tills exemplified by scts at Malinicc and Klcczcw near Konin. Geografia 20, 67-69.

Wasson, R. J. 1977: Last-glacial alluvial fan sedimentation in the Lower Dcrwcnt Valley, Tasmania. Sedimenrology 24, 781-7YY.

Weinhold. H. 1973: Bcitragc zur Kenntnis dcs Quartars im Wiirttemhergischcn Allgau zwischen ostlichcn Bodenscc und Altdorfer Wald. Diss. Tiibingcn.

Zicgler, H. J . 1976: 3.2. Quartar. I n Vollmayer. Th. & Zicglcr. H. J . : Geologische Kurre von Buyern 1:25.OOO. Erlaurerun- gen zum Blarr Nr. 8425 Weiler i. A//griu. Puhl. Bay. geol. Landcsamt, Miinchen.

BOREAS INQUA FORUM

Boreas, Vol. 12. p. 70. Oslo. 19830301

INQUA/ISSS Paleopedology Commission: Report from the President on present and future activities

Reports of thc Working Groups (WG) wcrc presented at the business meetings of the 1982 Congresses - ISSS in New Dclhi and INQUA in Moscow. Following these and additional con- sultations hctwccn mcmhcrs of thc Commission in Oxford. the WG were reorganized for the 1982-1987 period as follows.

I . The final rcport of thc Soil SIrurigruphy WG has hccn puh- lishcd in Ncwslcttcr No. 3 (1981). I t i s csscntially an unaltcred version of the previous one. The guide proposes the formdl use of the tcrm 'pcdoderm', for mappable soil stratigraphic units. defines i t and explains its relation to othcr stratigraphic units. Informally named facics arc suggcstcd for latcral (catcnary) variations. I t sccms best to rcst at this stagc and to promote the use of the guidc. especially in view of thc activitics of the US Committcc on Stratigraphy which sccms to promote thc tcrm 'gcosol'. The WG has thus hccn terminated. hut may be rc- constitutcd when need ariscs. Copies of thc guidc can he obtained from Dr. R. 9. Parsons.

2. The convcnor of thc WG on Daring of Pu1eo.sols (W. 1. Vrceken) has prcparcd a detailed rcpon on his activitics since 197X. The major part of this will he included in thc next Paleopedology Ncwslcttcr. He has also prcparcd two review papers on soil dating in relation l o landscape evolution which arc now in press. Background material has heen collcctcd for reviews on specific dating methods and a small numher of collaborators filled o u t the questionnaire of Dated Palcosols. Since Wim Vrcckcn has rcqucstcd to he rclicvcd of his func- tion as convcnor, this WG has now hccn tcrminatcd. Thc Rcgirtcr of Dated Paleosols will hc comhincd with the gcncral Rcgistcr of Palcosols organizcd by G. G. Bcckmann. A chap- tcr on Dating of Palcosols, hascd in part of thc WG rcport. will hc includcd in the Paleopcdology Handhook and prcparcd by 11. Polach and D. H. Yaalon (scc later).

3. Thc WG on the Origin und Narure of Pu/eo.so/s (G. G. Beckmann) had very good response from numerous collahora- tors on the Rcgister of Palcosols. Bcckmann's dctailcd report lists I21 rcgistcrcd palcosols with data and descriptions. Thcsc can he groupcd according to age. parcnt rock, covering matcrial, etc. Hc points out that the assembled matcrial may bc used

for indicating comparahlc scqucnccs and to point out rcscarch problems. Many more rcgistrations arc thus nccdcd. To facili- talc this. thc name of Ihc WG has been changed to Regisrer of Pu!eoso/s. It remains under the chairmanship of Gcoff Beck- mann. from whom collaborators can obtain the forms for the inclusion of additional palcosols in thc Rcgistcr.

4. The preparation of a Palcopedology Handbook was dccidcd on at thc INQUA Birmingham Congress. hut only preparatory stcps have heen takcn on this so far. Thc Commission deems this projcct a very worthwhile one. as such a handbook is necded by thc ever increasing numhcr of workcrs in various relatcd fields who cncountcr palcosols in the coursc of their work. They nccd a guide for recognizing, dcscrihing and an- alyzing thcm. Our Soviet colleagues have rccently published a small hook covering some of these aspects. I n order to promote this work, a WG charged with the prcparation of a Handbook on Paleopedology. with Dr . J. Catt (Harpenden) as chairman has been cstablishcd. He has alrcady prepared a li rators whom he i s rcqucsting to contribute spec The Handbook is planned to he rcady for the next INQUA Congress in 1987.

5. The Bibliography on Paleopedology compiled by Dr. A . Brongcr has now hccn puhlished and is ohtainahlc from the Secretary, Institute of Soil Scicncc, University o f Gdttingcn. I t contains 1900 entries from 29 countries for the ycars 1972- 1981, and together with the previous hihliography compiled by A. Rucllan compriscs an invaluahlc record and rcscarch tool . Wc wish to thank him for the successful completion of the project on timc.

6. Thc Sccrctary. Dr. K. W. G. Valentine, will continue to prcparc the Paleopedology Newslerrers. The ncxt onc is schc- dulcd for June 1983 and will include thc rclcvant parts of thc WG Reports. Additional material can he included. so do kccp him and us informed of your activities.

Dan H. Yaalon. Depurrmenr of Geology. The Hebrew Univer- sity of Jerusalem, Jerusalem. Israel; 5th November, 1982.

ice-marginal debris-flow deposits in western allgau, southern west germany

Documents