Quaternary Science Reviews 21 (2002) 503–523
The succession of ice-flow patterns in north-central
Que! bec-Labrador, Canada
Krister N. Janssona,*, Johan Kleman, David R. Marchantb
a
Department of Physical Geography and Quaternary Geology, Stockholm University, S-106 91 Stockholm, Sweden
b
Department of Earth Sciences, 675 Commonwealth Avenue, Boston University, Boston, MA 02215, USA
Accepted 15 February 2001
Abstract
Qu!ebec-Labrador, Canada, is one of the postulated dispersal centres of the Late Wisconsinan Laurentide Ice Sheet, and also
contains an unusually complex and rich glacial geological record. A reliable reconstruction of glaciation history represented by this
record would improve our comprehension of the dynamics of the eastern sector of the Laurentide Ice Sheet, such as the evolution of
the basal thermal regime and the timing of enhanced ice flow into Ungava Bay. We mapped glacial landforms over a 200,000 km2
area using aerial photographs, and conducted a detailed field-based survey of the central part of the area to establish the relative age
of crosscutting glacial-geological features. The position of the last ice remnant was south of Ungava Bay, well north of what has
commonly been perceived as the location for this dispersal centre. Southward (radial) flow from a northward migrating and
predominantly cold-based dispersal centre was the last glacial event in north-central Qu!ebec-Labrador. A widespread occurrence of
older ice flow traces towards the southwest was detected. In some areas, large drumlins, formed during this ice-flow event, occur in
alignment with landforms formed during the last deglaciation. This older southwestward flow is, however, overprinted by, and
therefore predates, traces of northward convergent flow into Ungava Bay (Ungava Bay flow), traces of a northeastward flow event,
and in some areas, traces of the deglacial flow event. Flutes and glacial striae indicating ice flow towards northeast are superimposed
on the Ungava Bay flow. The northeastward ice-flow system has been recognised across the mapped area, and because of its
direction and regional significance, we infer formation approximately during the Last Glacial Maximum. # 2002 Elsevier Science
Ltd. All rights reserved.
1. Introduction
The glacial geomorphology in Qu!ebec-Labrador is
dominated by two major glacial landform systems. One
is a radial pattern of till lineations, ribbed moraines, and
eskers that can be traced inwards from the peripheral
eastern, southern, and western parts of Qu!ebec-Labrador towards the central part of the peninsula. The other
major landform system is mainly composed of till
lineations, is strongly convergent, and indicates northward flow towards Ungava Bay (cf. Prest et al., 1968,
Glacial Map of Canada). The two landform systems
overlap in a U-shaped zone of intersection (Klassen and
Thompson, 1993; Veillette et al., 1999;), and northern
boundary of the zone of intersecting landforms is
referred to by Clark et al. (2000) as the Horseshoe
*Corresponding author. Tel.: +46-8-674-7158; fax: +46-8-164-818.
E-mail addresses: krister@natgeo.su.se (K.N. Jansson), kleman@natgeo.su.se (J. Kleman), marchant@crsa.bu.ed (D.R. Marchant).
Unconformity (Fig. 1). Two interpretations of the
Horseshoe Unconformity appear possible; (i) an ice
divide was located over the Horseshoe unconformity,
and the opposing flow systems formed more or less
simultaneously, with only minor shifts in ice divide
location, or (ii) two flow events, well separated in time,
are reflected, with the later involving a major ice divide
shift.
Early reconstructions of the Laurentide Ice Sheet
retreat in Qu!ebec-Labrador were to a large extent based
on the spatial pattern of glacial meltwater traces, such as
glacial lake shorelines (Ives, 1960a, b; Barnett, 1963;
Harrison, 1963; Barnett and Peterson, 1964; Peterson,
1965; Ives et al., 1976). These reconstructions depict an
ice marginal recession towards a final position in the
Schefferville area. Reconstructions by Prest (1970),
Shilts (1980), Dyke et al. (1982), Boulton et al. (1985),
Dyke and Prest (1987), Gray et al. (1993), and Parent
et al. (1995) show a Lateglacial ice flow from a U-shaped
ice divide centred over the Horseshoe Unconformity.
0277-3791/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S 0 2 7 7 - 3 7 9 1 ( 0 1 ) 0 0 0 1 3 - 0
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K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
Fig. 1. This figure shows the Horseshoe Unconformity as defined by
Clark et al. (2000). The Horseshoe Unconformity is the northern limit
of the zone where the Ungava Bay landform swarm and the till
lineations and eskers of the radial fan coexist (last deglaciation).
Landform data from the Glacial Map of Canada (Prest et al., 1968).
Boulton and Clark (1990a, b) suggest an interpretation in which the Horseshoe Unconformity does not
define an ice divide, and also consider the northward
Ungava Bay flow to be younger than the radial flow.
Glacial Lakes Naskaupi and McLean (Ives, 1960a, b;
Matthew, 1961; Barnett and Peterson, 1964; Peterson,
1965; Barnett, 1967; Clark and Fitzhugh, 1990) are
incorporated in deglacial reconstructions by e.g. Prest
(1970), Dyke and Prest (1987), Vincent (1989), and
Stravers et al. (1992). The crux is that these reconstructions do not include, and fail to explain, the existence of
the numerous glacial lakes (Fig. 2) that existed during
the last deglaciation to the west and south of Ungava
Bay (Hughes, 1964; Taylor, 1982; Lauriol and Gray,
1983, 1987; Allard and Seguin, 1985; Gray and Lauriol,
1985; Gray et al., 1993; Jansson, unpublished manuscript map)
The evidence for the latter group of lakes makes the
concept of a U-shaped Lateglacial ice divide problematic, because many of these glacial lakes were located
right under, or on the wrong side of this hypothetical ice
divide.
Kleman et al. (1994), Jansson and Kleman (1999) and
Clark et al. (2000) suggest that the till lineations that
converge towards Ungava Bay reflect a relict landscape
preserved due to cold-based conditions, at least during
the last deglaciation. Consequently, Kleman et al. (1994)
and Clark et al. (2000) reconstructed a Lateglacial ice
remnant positioned over the Ungava Bay landform
swarm, frozen to its bed and with an ice divide extending
in a NNW–SSE direction. Kleman et al. (1994)
suggested that the last ice remnant was elongated and
situated across the lower reaches of Arnaud, Feuilles,
and M!el"ezes Rivers (Fig. 2) while Clark et al. (2000)
reconstructed a late fragmentation of an elongated ice
divide into residual ice caps and glaciers. Both these
deglacial ice sheet configurations are compatible with
the existence and outline of glacial lakes in north-central
Qu!ebec-Labrador during the last deglaciation.
Based on the interpretation of striae observations in
the Caniapiscau Reservoir area, stacked into local iceflow sequences, Veillette et al. (1999) argued against the
Kleman et al. (1994) interpretation of the Ungava Bay
landform swarm as a preserved relict landscape.
Veillette et al. (1999) interpreted the Ungava Bay
landform swarm as a young ice-flow system correlative
with the Gold Cove advance (9.9 ka). The Horseshoe
Unconformity was interpreted as the southern limit of
Lateglacial convergent flow toward Ungava Bay, which
captured the southwestward component of the radial
flow in the Caniapiscau Reservoir area (Fig. 1).
In this paper, we present new evidence concerning the
relative age of ice-flow events and successive ice sheet
configurations in central Qu!ebec-Labrador. We argue
that the interpretation of the Ungava Bay landform
swarm as the youngest ice flow in the area (Veillette
et al., 1999) is incompatible with our observations that
this landform swarm is overprinted or truncated by at
least three discrete landform swarms indicating other
flow patterns.
2. Methods
2.1. Field observation
Detailed glacial geological field mapping was conducted in an area 5–10 km west of Lac Rousson in the
eastern part of the Caniapiscau Reservoir, Qu!ebec, in
1997 and along the Radisson-Caniapiscau Reservoir
road in 1999 (Fig. 3). The excavation associated with the
K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
505
Fig. 2. Map showing the outline of glacial lakes in the area. The approximate outline of the damming ice margin is indicated. The inset map shows
the approximate deglacial ice-margin reconstructed from southward sloping lateral meltwater channels recording the last deglaciation north of the
Horseshoe Unconformity and glacial lake outlines.
construction of the dam has cleared the bedrock from
the drift at many sites. During fieldwork, the water level
of the Caniapiscau Reservoir was low (estimated at 15–
20 m below maximum level). Wave erosion of glacial
deposits since the construction of the dam has cleared
extensive areas of bedrock, revealing abundant glacially
polished surfaces. The bedrock on most examined
outcrops consists of gneissic granite or amphibolite.
Sites at lake shorelines were studied critically due to
the possibility of striae having been formed by boulders
entrained in lake ice during ice push. Striae formed
by ice push are expected to be broader and less
consistent, both locally and regionally, than glacial
striae (Liverman and Vatcher, 1992). Moreover, we
observed that ice push striae in the study area are not
associated with glacially polished surfaces and exhibit
signs of a non-linear ice flow with sharp deflections in
flow direction. Striae with the described properties were
rejected.
Striae data from 73 sites are shown in Table 1. Iceflow trends were determined using striae, glacial grooves
and rat-tails (Ljungner, 1949; Flint, 1971; Stro. mberg,
1971). The direction of ice flow was determined using
the following criteria (Fig. 4):
*
*
*
Rat-tails; head pointing up-ice (Prest et al., 1968;
Vorren, 1979; England, 1986; Veillette, 1986; Shilts
and Smith, 1989; H.attestrand and Stroeven, 1996).
Smooth glacial facing edge of outcrop irregularities
(Stro. mberg, 1971).
Medium-scale, stoss- and lee-side features (Vorren,
1979).
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K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
Fig. 3. Box shows the investigation area where the glacial geomorphology was interpreted from aerial photographs. The dark-grey area was covered
by an expanded interpretation of aerial photographs, in order to trace the continuation of the ice flow systems present within the investigated area.
The light-grey area was covered by interpretation of microfilm copies of aerial photographs. The inset map shows numbered boxes that refer to
stereograms. Dashed area shows area of detailed fieldwork and dashed line shows the Horseshoe Unconformity.
*
*
*
Crescentic gouges (Ljungner, 1930; Harris, 1943;
Embleton and King, 1975).
Deflection of striae due to bedrock topography, on
the stoss-sides of roches moutonn!ees.
Microscale smoothing of glacial facing edges
(Stro. mberg, 1971).
Shaw (1994) and Pair (1997), suggest that rat-tails can
result from meltwater erosion under glaciers and icesheets. Nevertheless, rat-tails encountered in this study
were strictly parallel and associated with glacial striae,
indicating formation by direct glacial erosion (cf.
H.attestrand and Stroeven, 1996).
The relative age between ice flow trends was
determined by crosscutting relationships between striae
sets. The following criteria (Stro. mberg, 1971; Klassen
and Bolduc, 1984; H.attestrand and Stroeven, 1996) were
used to determine the relative age of different ice-flow
directions (Fig. 4).
*
*
*
Striae preserved in lee-side positions relative to other
striae sets are older.
Striae that occur on crests between grooves and
coarse striae are younger.
Striae cut into other striae or grooves are younger.
K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
507
Table 1
Table shows the result of striae mapping in the investigation area. The positions were measured by GPS. Increasing number of crossbars indicate
increasing relative age. dbt refers to deflection due to bedrock topography, cg to crescentic gouge, sfe to smooth glacial facing edge of outcrop
irregularities, mslt to medium-scale stoss- and lee side topography, r-t to rat-tail, and msfe to micro-scale smoothing of glacial facing edge. R-t for rat-tail,
s for striae, and g for glacial groove indicate type of striation. For explanation of ice-flow direction indicators see Fig. 4. Shaded sites are shown in Fig. 5
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K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
Table 1. Continued
scale glacial geomorphology in microfilm, a test area of
100 100 km was chosen where both aerial photographs
and microfilm images were used for interpretation. This
study shows a good agreement in interpreting all
landforms except small glaciofluvial channels, which
were underrepresented in the mapping based on microfilm images.
An expanded interpretation of aerial photographs
and microfilm copies of aerial photographs was also
conducted over neighbouring areas, in order to trace the
continuation of the ice flow systems present within the
investigation area (Fig. 3).
2.3. Use of glacial geomorphology to reconstruct palaeo
ice-flow systems
2.2. Geomorphological mapping
The glacial geomorphology was mapped by interpretation of black and white aerial photographs at scales
of 1 : 60 000 by using a stereoscope with 2–16 magnification and microfilm copies of aerial photographs at scales of 1 : 30 000 to 1 : 60 000 by using a
microfilm reader for non-stereo interpretation (Fig. 3).
The microfilm reader shows the photos in their original
size. To test the quality of interpretation of the small-
The inversion model used to reconstruct palaeo-ice
flows from geomorphological data comprises a classification system for glacial landform assemblages and a
stepwise deciphering procedure (Kleman and
Borgstro. m, 1996). The main components in this inversion model are fans. Fans are the simplified and spatially
defined map representations of glacial landform swarms.
The pattern of a fan is determined on the basis of spatial
continuity and/or the resemblance to a glaciologically
plausible pattern (cf. Kleman and Borgstro. m, 1996).
Similar criteria for the delineation of flow sets were used
by Boulton and Clark (1990a, b), Clark (1999), and
Clark et al. (2000). The difference between the Boulton
and Clark (1990a, b) model and the Kleman and
Borgstro. m (1996) model is that the latter includes the
glacial meltwater system. The Clark et al. (2000) model,
like the Kleman et al. (1994) model, incorporates eskers
but does not include other components of the meltwater
system such as lateral meltwater channels.
Eskers form inward-transgressively, close inside re( mark, 1989;
treating ice margins (Hebrand and A
Bolduc, 1992; Clark and Walder, 1994) and are therefore interpreted by Kleman and Borgström (1996) and
Clark et al. (2000) to reflect the general ice flow direction
during the deglaciation. Flights of lateral meltwater
channels reflect ice marginal drainage, in the ice-surface
slope direction (Mannerfelt, 1945; Dyke et al., 1992;
Kleman, 1992; Sollid and Srbel, 1994). Marginal
drainage is favoured by cold-based conditions (Maag,
1969; Sugden and John, 1976; Dyke, 1993) and extensive
flights of lateral meltwater channels are interpreted as a
marker of a frozen-bed deglaciation fan (Kleman and
Borgstro. m, 1996). Glacial lake traces are useful for
determination of the approximate outline of damming
ice margins during deglaciation phases (Borgstro. m,
1989; Kleman and Borgstro. m, 1996).
The fan types recognised in this work are; wet-bed
deglaciation fans, frozen-bed deglaciation fans, and
synchronous fans. A wet-bed deglaciation fan consists of till lineations and aligned eskers. Frozen-bed
K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
509
Fig. 4. Criteria for the interpretation of ice-flow direction, and for establishing crosscutting relationships between sets of striae of different ages. The
approximate sizes relate to features found in the investigation area.
deglaciation fans are dominated by lateral meltwater
channels and have no or little lineation imprint related
to Lateglacial stages. Unaligned till lineations from an
older glacial event may be present. Synchronous fans are
defined by till lineations, but lack aligned eskers. They
are therefore interpreted to have formed by flow well
inside of the esker-forming marginal zone. Due to the
lack of dating methods pertaining to the subglacial
environment they represent events that can only be
addressed on a relative, but not absolute, time scale. As
a first-order approximation we assume that the flow
traces in such a fan formed synchronously over its area,
and that they therefore reflect true flow patterns (cf.
Kleman and Borgstro. m, 1996; Clark et al., 2000).
In the deciphering procedure, relative chronologies
are established, using crosscutting striae and till lineations. The fans are then sorted into relative-age stacks.
For the determination of crosscutting relationships and
relative chronologies of till lineations the model of
subglacial modification by Clark (1994) was used.
Details of the model used in reconstructing palaeo iceflows are described elsewhere (Kleman and Borgstro. m,
1996). It has been used previously in similar attempts to
reconstruct palaeo-ice-flow from the glacial landform
record present in Scandinavia (Kleman et al., 1997).
3. Results
3.1. Roches moutonne!es
Roches moutonn!ees are widespread in the Lac
Rousson area and have typical widths and lengths of
5–10 m and protrude 0.5–3 m above the drift surface.
The shape of the roches moutonn!ees indicates formation
by ice-flow approximately towards the north.
3.2. Glacial striae
Evidence for at least five ice-flow events is present in
the striae record (Table 1 and Fig. 5). The relative ages
relationship, are shown in Table 2 and Fig. 5. The split
up of striae data into distinctive striae sets (striae sets
I–V) is based on position, orientation and relative age.
3.2.1. Striae set I
Striae indicating a young ice flow towards the SW/
SSW are present at most sites west and north of the
Caniapiscau Reservoir (Table 1 and Figs. 5 and 6).
The relative age to other systems was determined at 20
sites (Table 2).
3.2.2. Striae set II
Striae indicating ice flow towards the NE are
preserved at 4 sites (Table 1) in stoss-side positions on
roches moutonn!ees. Faintly inscribed striae typically
occur on the most exposed bedrock surfaces, superimposed on striae indicating ice flow towards the N. The
ice-flow direction was determined at site 10, where
smooth glacial facing edges of outcrop irregularities
indicated ice flow towards the northeast.
The relative age to other systems was determined at
sites 5, 7 and 10 (Table 2 and Fig. 5).
3.2.3. Striae set III
Striae indicating ice flow towards the N (Table 1 and
Figs. 6 and 7) show some scatter in striae direction.
Crosscutting relationships exist between striae indicating an ice flow towards N/NNE, and striae indicating ice
flow towards N/NNW west of Lac Rousson and north
of the Caniapiscau Reservoir. These small-angle crosscutting relationships at 9 sites may indicate either minor
directional changes during this flow event, or that
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K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
Fig. 5. Striae observations. The ice-flow direction is towards the observation point. Increasing number of crosslines indicates increasing relative age.
Some closely spaced sites have been excluded in figure due to limited space. The inset figure shows the known relative age relationships of striae sets
(ss). Number refers to striae sets. The position in relation to the lines indicates the relative age, i.e. ss V is known to be older than ss III, but the
relationship to ss IV is not established. For a complete description of the sites see Tables 1 and 2.
been restricted (in the order of centimetres to a few
decimetres) during this ice-flow event (events), because
striae from the older ice-flow direction towards the ENE
are still preserved in shallow hollows and open joints on
the stoss-side and top surfaces of roches moutonn!ees
(Fig. 7).
Relative age relationships between the N–NNE
(Striae set IIIa) and N–NNW (Striae set IIIb) directions
during this event were detected at 4 sites, with the
younger Striae set IIIa cut into striae set IIIb. The
relative age of striae set III could be established by the
interpretation of cross-striated outcrops at 17 sites
(Table 2 and Fig. 5).
Fig. 6. Exposure at Site 29 showing striae set III, indicating ice flow
towards the N (3558), preserved in lee-side position relative to younger
southwestward (2168) ice flow (striae set I). The area is situated 5 km
southwest of the Caniapiscau Reservoir dam. Photo: K.N. Jansson.
separate ice-flow events formed the different striae
directions (Table 1). Ice-flow direction approximately
towards the north is represented at 24 sites (Table 1).
The erosion of the outcrops at sites 1–11appears to have
3.2.4. Striae set IV
Striae indicating older ice flow towards the W/SW are
preserved at 17 sites (Table 1 and Fig. 5). The relative
age between striae set IV and striae sets III and I was
determined at 15 of 17 sites (Table 2). Striae and glacial
grooves of striae set IV are preserved in lee-side
positions relative to the younger sets III (at 4 sites)
and I (at 5 sites). The younger striae sets III and I cut
into striae set IV at 6 and 1 sites, respectively (Table 2).
K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
511
Table 2
Sites where relative age relationships were established. Ice flow is
towards the position marker. For description of relative age criteria,
see Fig. 4
Fig. 7. Striated exposure at site 5: Striae (striae set V) indicating ice
flow towards the ENE (varying between 688 and 748) are preserved in a
lee-side position relative to younger northward trending striae (striae
set III, varying between 08 and 148). The area is situated 5–10 km
southwest of Lac Rousson in the southeastern part of the Caniapiscau
Reservoir. Photos: K.N. Jansson.
3.2.5. Striae set V
Striae indicating ice flow towards the ENE southwest
of Lac Rousson are preserved in lee-side positions of
later glacial erosion by ice flowing towards the north
and northeast. The east–northeastward striae occur in
positions such as lee-side facets on roches moutonn!ees
(Fig. 7) and in local lee-side positions on the top surface
of roches moutonn!ees. This ice-flow direction is
recorded at 3 of 6 sites (Table 1).
The relative age of the ENE ice flow in the Lac Rousson
area could be determined at 5 of 6 sites (Table 2). Striae
and glacial grooves indicating ice flow towards the ENE
were preserved in lee-side positions relative to younger
sets of striae (striae set III, see Fig. 7 and striae set II).
Fig. 9. At least five different ice flow systems, fans A–E
(from younger to older) occur in the area.
3.3. The glacial geomorphology
3.3.1. Fan A (last deglaciation)
The radial fan A (Fig. 9a) is defined by eskers, ribbed
moraine, lateral meltwater channels, glacial lake traces
and till lineations (Figs. 8, 10 and 11). Fan A is classified
as a wet-bed deglaciation fan with a transition to a
frozen-bed deglaciation fan at the Horseshoe Unconformity. North of the Horseshoe Unconformity the
deglaciation pattern is only traceable through the
presence of lateral meltwater channels indicating an ice
surface slope towards the south (Fig. 10), and glacial
lake traces. These meltwater features indicate a coldbased retreat towards the north and northeast during
the last deglaciation (Inset map Fig. 2). The landforms
of fan A are always the youngest when crosscutting with
other landform system occurs (Figs. 9a, 10 and 11).
The results from the mapping of glacial geomorphology are shown on Fig. 8. The fans we defined, and the
crosscutting relationships between them, are shown on
3.3.2. Fan B
Fan B has sharply defined boundaries and consists of
drumlins, horned crag-and-tails, crag-and-tails, and
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Fig. 8. Glacial geomorphology mapped from the interpretation of aerial photographs in the Caniapiscau Reservoir area.
flutes, that indicate ice flow towards the east (Figs. 8 and
9b). Fan B reaches as far east as the Menihek Lakes
(Fig. 12). Fan B is classified as a synchronous fan and
overprints fan D and E, but is overprinted by fan A
(Figs. 9b and 12). The relative chronology between fan
B and fan C is not established.
3.3.3. Fan C
Fan C consists of indistinct flutes, in the Caniapiscau
Reservoir area, indicating ice flow towards the northeast, overprinted on fan D (Figs. 8, 9c and 13). Fan C till
lineations northwest of Smallwood Reservoir, at the
southern part of the George River, and in the Whitegull
Lake area (Fig. 14) is larger than those in the
Caniapiscau area. Fan C is classified as a synchronous
fan.
3.3.4. Fan D (Ungava Bay landform swarm)
Fan D is defined by drumlins, crag-and-tails, horned
crag-and-tails, and flutes indicating ice flow converging
towards Ungava Bay (Figs. 8 and 9d). Our air photo
interpretation of the central part of the Ungava Bay
landform swarm reveals a complexity of fan D
previously not recognised. Fan D appears to consist of
at least five well defined segments, each representing
different ice-flow events (Fig. 15), possibly formed
during a sequence of rapid-flow events closely spaced
in time. Crosscutting relationships between segments of
this fan were described by Clark (1994) and Clark et al.
(2000). Each segment shows a convergent flow, abrupt
lateral margins, and attenuated till lineations (Fig. 15).
Fan D is interpreted as a composite composed of several
segments that formed close in time, and with the same
overall ice configuration.
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Figs. 8 and 9 show a simplified picture of fan D. Fan
D overprints fan E but is overprinted by fans A (Figs. 10
and 11), B, and C (Fig. 13).
Fan D (Ungava Bay landform swarm) is well defined
by till lineations as far south as 60 km south of the
Caniapiscau Reservoir (Fig. 15). However, horned cragand-tails (cf. Jansson and Kleman, 1999) indicating ice
flow towards north occurs as far south as the Lac
Opiscoteo area. Likewise, striae indicating ice flow
towards north and northeast with a relative age fitting
well with the age of the formation of Fan D exist 100 km
southwest of the Horseshoe Unconformity (Fig. 9d).
These outliers are well outside of the contiguous extent
of Fan D. Hence, it is possible that the zone where fans
A and D intersect is up to 100 km wide. It appears
probable that up-ice parts of fan D were largely eroded
by the radial deglacial flow (Fan A). The size of the
lineations in Fan A, and the intensity of erosion,
decreases towards northwest and the Horseshoe Unconformity. It therefore appears likely that the mapped
extent of the Fan D is a minimum estimate. The
southward extent of fan D is not critical to the
interpretation of the glacial history of the area.
3.3.5. Fan E
Fan E is defined by large drumlins and crag-and-tails,
often several kilometres long, indicating ice flow
towards the southwest in the southern part of the
investigated area, and towards the west in the western
part of the area (Figs. 8, 9e and 11). Fan E is classified as
a synchronous fan. Fan E is always the oldest when
crosscutting relationships occur (Figs. 9e and 11). Fans
A and E show similar ice flow directions in the western
part of the area (Fig. 8), but diverge in the southern part
of the area. A striking difference between the till
lineations of fan A and E is that the drumlins and
crag-and-tails of fan E are always larger than the till
lineations of fan A. Clark et al. (2000) also observed
differences in size distribution between these two landform systems.
In some parts of the area, the scattered pattern of
preserved drumlins and crag-and-tails of Fan E may be
explained by more effective glacial erosion during the
formation of younger fan A in the northwestern part of
the area and Fan D in the central and northeastern part
of the area (Fig. 8). The coherent core area of fan E is
located between Caniapiscau reservoir and Lac Opiscoteo. Whether the outlying parts shown in Fig. 9e really
form part of this fan is unclear.
513
3.4. Interpreted correlation between striae and glacial
landform data
The possibility and probability of correlations between striae and till lineations were discussed by Kleman
(1990) and Clark et al. (2000). Till lineations are surface
forms, and because crosscutting is always associated
with remoulding of the older forms, it is rare to find
more than two directions in till lineations at any given
site.
Striae, on the other hand, are primarily protected
through till burial, and by local protection on lee-side
facets. In fortunate circumstances multiple ice flow
directions can be recorded at one site. There are several
possible reasons why correlation between striae and till
lineation data may be difficult. In heavily till covered
terrain, striae corresponding to young flutes may be
lacking because the ice was nowhere in contact with
bedrock. Alternatively where till cover is sparse, flutes
may be absent. There are also cases where the
morphological imprint on e.g. old large drumlins is
negligible despite a changed flow direction that is
recorded by striae.
We suggest, based on striae chronologies from the
Lac Avezac area established by Veillette et al. (1999),
that striae set V is older than striae set IV (Fig. 16).
Veillette et al. (1999), interpreted the east–northeastward ice flow to be the oldest, preserved in lee-side
positions of a youngest ice flow towards the NNW and
an ice flow of intermediate age towards the SW. We
suggest that Veillette’s et al. (1999) ice flow towards the
NNW correlates to striae set III and fan D (Ungava Bay
flow), the ice flow towards the SW correlates to striae set
IV and fan E, and that the ice flow towards the ENE
represent the oldest, in striae, detected glacial event in
the area.
The faintly inscribed flutes of fan C are suggested to
correlate to striae indicating ice flow towards northeast
(striae set II) in the Lac Rousson area (Figs. 5 and 16).
The correlation is based on the spatial continuity
eastward and the indications of restricted glacial erosion
both in the striae record and the glacial landform data.
The well-developed lineations of fan B indicates ice
flow towards the east, but very little striae data exists
from the area (Fig. 16).
Fan A is formed during the last deglaciation and
correlates well to striae set I (Fig. 16).
4. Discussion
3.3.6. Northwestward ice flow
Scattered till lineations indicating ice flow towards the
northwest occurs at the northern, western and southwestern part of the Caniapiscau Reservoir. Similar
directions are recorded south of Lac Boilay by cragand-tails (Fig. 8 and 9f).
Crosscutting relationships within the striae record and
between fans indicate major dispersal centre shifts
between ice-flow events in central Qu!ebec-Labrador.
Fig. 17 shows a generalised picture of the ice flow
evolution of central Qu!ebec-Labrador.
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K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
515
Fig. 10. Stereograms of intersecting till lineations (fans C and D) and lateral meltwater channels (fan A). Lateral meltwater channels north of the
Horseshoe Unconformity, indicating an ice marginal retreat towards the northeast (fan A). Till lineations indicating ice flow towards ENE (fan C)
overprinting till lineations indicating ice flow towards NNE (fan D). For location see inset map in Fig. 3. This aerial photograph # 1973. Her
Majesty the Queen in Right of Canada, reproduced from the collection of the National Air Photo Library with permission of Natural Resources
Canada.
4.1. Ice flow systems younger than the Ungava Bay
landform swarm (fan D)
4.1.1. Deglaciation (fan A)
Lateral meltwater channels in the northern part of the
Caniapiscau Reservoir area and in the Lac du Sable,
Chastrier, and Avezac areas (Figs. 8 and 10) indicate an
ice surface slope towards the southwest, south, and
southeast, for a distance of at least 50 km north of the
Horseshoe Unconformity (Kleman et al., 1994; Jansson,
unpublished manuscript map). The last stage in the
glacial history is therefore inferred to have been ice flow
towards the south (Fig. 17). No striae north of the
Horseshoe Unconformity record this flow direction, but
the distribution and outline of the glacial lakes (Fig. 2)
in the area is only compatible with an ice marginal
retreat towards the north, at least to the position of the
ice margin shown in Fig. 2.
Veillette et al. (1999) interpreted, based on striae
(indicating ice flow towards W to SSE), the radial
pattern of till lineations, eskers, and ribbed moraine as
reflecting a reorganisation of the ice divide and a
successive change in ice-flow direction. The relative
chronologies we have established (Fig. 16) indicate that
striae towards W (striae set IV, west of Caniapiscau
Reservoir) and towards the SW (southwest of the
reservoir) were formed during a pre-last deglacial ice
flow. This interpretation is strengthened by the fact that
3
Fig. 9. Outline of fans A to E and the scattered pattern of northwestward trending striae and till lineations, based on aerial photo interpretation.
Relative age assignments, documented by crosscutting till lineations and striae, are compiled from this work, Hughes (1964), Prest et al. (1968),
Klassen and Thompson (1993), Veillette (1995), and Veillette et al. (1999). A broken line marks the Horseshoe Unconformity. Legend from Fig. 8. (a)
Fan A is classified as wet-bed deglaciation fan with a transition to a frozen-bed deglaciation fan at the Horseshoe Unconformity. (b) Fan B has
sharply defined boundaries and consists of till lineations such as drumlins, crag-and-tails, and flutes that indicate ice flow towards the east. Fan B is
classified as a synchronous fan. (c) Fan C consists of weakly defined flutes, indicating ice flow towards the northeast. Fan C is classified as a
synchronous fan and interpreted to have formed at, or near, the Last Glacial Maximum. (d) Fan D (Ungava Bay landform swarm) is well defined by
till lineations as far south as 60 km south of the Caniapiscau Reservoir. However, the possible westerly and southerly outliers of Fan D may expand
the southerly extent of fan D to the Lac Opiscoteo area, 100 km south of the Horseshoe Unconformity. The picture shows a simplified view of fan D,
which we suggest to consist of 5 different segments in central Labrador-Qu!ebec (Fig. 16). (e) Fan E is defined by large drumlins and crag-and-tails,
often several kilometres long. Fan E is the oldest detected coherent landform system in the area and is classified as a synchronous fan. Note that fan
A and E show similar ice flow directions in the western part of the area. The coherent core area of fan E is located between Caniapiscau reservoir and
Lac Opiscoteo. Whether the outlying parts (broken lines) shown really form part of this fan is unclear. (f) Distribution of scattered NW–SE trending
till at the northern and eastern part of the Caniapiscau Reservoir. Similar directions are recorded south of Lac Boilay by crag-and-tails indicating ice
flow towards the northwest.
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K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
Fig. 11. Eskers and ribbed moraine 3 km northwest of Lac Chastrier, indicating ice flow towards south–southwest are interpreted to be a part of the
radial deglacial flow (fan A) correlate well with the SW to NE trending till lineations (fan A). The large crag and tails indicating ice flow towards
WSW correlate well in orientation and size of other drumlins and crag-and-tails in the area (fan E). Also an S to N trending till lineation (fan D) is
overprinted by till lineations of fan A in the northern part of the stereogram. For location see inset map Fig. 3. This aerial photograph # 1973. Her
Majesty the Queen in Right of Canada, reproduced from the collection of the National Air Photo Library with permission of Natural Resources
Canada.
Fig. 12. The distribution of fan B till lineations and eskers in northcentral Qu!ebec-Labrador. Fan B is obliquely overprinted by eskers
formed during the last deglaciation. Esker data is compiled from the
Glacial map of Canada (Prest et al., 1968).
Ives (1960c) recorded ‘older’ ENE–WSW trending
striations in the Helluva Lake area and also by
observations made by Klassen et al. (1992) from the
Lac Avezac area recording SW–NE trending striae older
than a northward flow (fan D) and a southeastward flow
(fan A). Veillette et al. (1999) disregarded the age of
these striae and correlated them to the last deglaciation.
We suggest these ice flows reflect separate ice flow events
(see discussion under fan E).
The abundance of ribbed moraine increases from
southwest to northeast, towards the southern and
western part of the Horseshoe Unconformity, where
they abruptly cease to exist (Fig. 8). It has recently been
suggested that ribbed moraines are formed by brittle
fracturing of subglacial sediments, induced by the stress
between proximal frozen- and distal thawed-bed areas
(H.attestrand, 1997; H.attestrand and Kleman, 1999;
Kleman and H.attestrand, 1999). The lack of ribbed
moraine north of the Horseshoe Unconformity indicates
that this area experienced cold-based conditions during
the last deglaciation.
We suggest, based on crosscutting till lineations, the
pattern of eskers, flights of lateral meltwater channels,
and glacial lake traces, that the ice dispersal centre
during the last deglaciation was situated well north of
the Caniapiscau Reservoir (inset map of Fig. 2 and
Fig. 17). This is in agreement with suggestions of a late
ice dispersal, responsible for the damming of the glacial
lakes, centre south of the Ungava Bay (Gray and
Lauriol, 1985; Clark et al., 2000).
4.1.2. Fan B
Fan B consists of large drumlins, crag-and-tails,
horned crag-and-tails, and flutes, indicating ice flow
towards the east (Figs. 9 and 12). Till lineations of fan B
was previously recognised by Stevenson (1963), Klassen
et al. (1992) and as Flow event IV in Klassen and
K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
517
Fig. 13. Stereograms of crosscutting till lineations. For location see inset map Fig. 3. The stereograms cover areas in the northwestern part of the
Caniapiscau Reservoir. We interpret the WSW–ENE trending flutes to either reflect the ice flow of fan A or C. These flutes crosscut large till
lineations of fan D and clearly show that the formation of fan D was not the last glacial event in the area. This aerial photograph # 1954. Her
Majesty the Queen in Right of Canada, reproduced from the collection of the National Air Photo Library with permission of Natural Resources
Canada.
Thompson (1993) and fan D in Kleman et al. (1994). In
the area of fan B there are only a small number of till
lineations of fan D (Ungava Bay flow), probably due to
erosion during the younger fan B event.
The abrupt lateral margins and the attenuated till
lineations of fan B (Fig. 12) satisfy criteria for identifying former ice streams (Stokes and Clark, 1999). These
characteristics indicate that fan B was formed by fast
flowing ice (an ice stream), which also is suggested by
Klassen and Thompson (1993), emanating from an ice
dispersal centre west of Caniapiscau Reservoir
(Fig. 17d). Jansson and Kleman (1999) suggest that the
abundant horned crag-and-tails of the Ungava Bay
landform swarm (fan D) were formed during a brief
period of thawed-bed conditions. The existence of a
small number of horned crag-and-tails in fan B may
indicate similar conditions during the formation of fan
B.
Ice flowing towards E is recognised in the striae and
till lineation record by Veillette et al. (1999, their
Fig. 12) but form no part of their reconstruction of the
ice flow sequence.
4.1.3. Fan C
NE–SW trending till lineations in north-central
Qu!ebec was observed by Wilson et al. (1953). We
suggest that fan C, with ice flow towards NE, correlates
with these early observations. Fan C also correlates
(Fig. 14) with event V of Klassen and Thompson (1987,
1993); fan C of Kleman et al. (1994); striae in the
Caniapiscau Reservoir area (Hughes, 1964; Prest et al.,
1968); striae in the Schefferville area (Henderson, 1959;
Kirby, 1961; Baragar, 1963; Hughes, 1964; Prest et al.,
1968; Klassen et al., 1992; Liverman and Vatcher, 1992,
1993; Kleman, unpublished, 1998); and striae and till
lineations at the southern part of the George River
(Prest et al., 1968; Klassen and Thompson, 1993).
Our observations of faintly inscribed NE–SW oriented striae and till lineations (Figs. 8 and 13) are in
agreement with Kirby (1961), who described a late
ice flow towards the NE, that had little effect on
previously deposited sediments. The probable location
of the dispersal centre during the fan C flow was well to
the southwest of the investigation area (Fig. 14), in the
vicinity of the postglacial uplift centre (Veillette et al.,
1999). This may indicate that fan C was formed by a
full-grown Laurentide ice sheet, possibly close in time to
the Last Glacial Maximum (LGM). The absence or
restricted occurrence of flow traces (fan C) in the vicinity
of the implied ice dispersal centre during LGM could be
explained by either cold based conditions (cf. Denton
and Hughes, 1981) or very restricted erosion due to low
velocities beneath the ice dispersal centre (cf. Boulton
and Clark, 1990a). The patchy occurrence of till
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K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
Fig. 14. Distribution of NE-trending till lineations and striae of fan C (blue lines), and the esker distribution. Fan C is obliquely overprinted by eskers
formed during the last deglaciation. We suggest that the northeastward trending till lineations and striae in the Caniapiscau Reservoir area (Fan C)
correlate to the till lineations and striae in the Schefferville area and in the southern part of the George River area. We suggest fan C to temporally
reflect the near-LGM flow with an ice dispersal centre situated west of the Caniapiscau reservoir area (dashed line). Thin solid lines indicate inferred
ice surface topography during fan C flow.
lineations in the fan C area can be explained by nonuniform glacial erosion and accumulation in those areas
during the last deglaciation.
We suggest fan C to temporally reflect the near-LGM
flow and fan B to reflect a northward migration of the
dispersal centre, induced by the northward retreat of the
southern ice margin. The implication of these suggestions is that fan B is younger than fan C.
Striae correlative to fan C are included in Veillette
et al. (1999, their Fig. 13), but do not form part of their
reconstruction of the regional ice flow pattern. The lack
of recognition of ice flow events C and B has important
implications for their interpretation of the Ungava Bay
swarm as the youngest ice flow in the area.
4.2. Fan D (Ungava Bay landform system)
The superposition of fans B and C on fan D (Ungava
Bay landform swarm) clearly shows that the Ungava
Bay landform swarm is not the last major ice flow event
in the area, and hence, is unrelated to the final
deglaciation of Qu!ebec-Labrador (Figs. 9 and 13). We
suggest, in agreement with Kleman et al. (1994), Kleman
and H.attestrand (1999) and Clark et al. (2000), that the
till lineations that indicate a convergent ice flow towards
Ungava Bay reflects a relict landscape preserved due to
cold based conditions during at least the last deglaciation. Veillette et al. (1999) argue against the Kleman
et al. (1994) interpretation of the Ungava Bay landform
K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
Fig. 15. Fan D consists of at least five well-defined and partly crosscutting segments, each representing different ice-flow events. Each
segment shows convergent flow, abrupt lateral margins, and attenuated till lineations. Fan D is a composite of several individual
synchronous fans, formed by a succession of rapid-flow events. The
figure only shows crosscutting relationships within till lineation of
different sections of fan D.
swarm as a relict landscape preserved during cold-based
conditions. Nevertheless, Veillette et al. (1999) show, in
their Fig. 6A, the distribution of fossil till lineations west
and south of the Horseshoe Unconformity, indicating
ice flow towards the N to NNE, which they separate
from the very similar till lineation pattern north of the
Horseshoe Unconformity. We argue against a separation in time of these till lineation features and suggest, in
agreement with Clark et al. (2000), that the southern
extent of the relict fan D widely exceeds estimates by
Veillette et al. (1999).
Veillette et al. (1999) and Clark et al. (2000) suggest,
based on spatial conformity within till lineations of the
Ungava Bay landform swarm (fan D), that the southcentral part of this landform system were formed during
a Lateglacial advance (Kaufman et al., 1993; Manley,
1996; Pfeffer et al., 1997) of ice that reached the southern
part of Baffin Island, the Gold Cave advance. However,
the south-central part of the Ungava Bay landform
swarm is, as shown by angular unconformities and
crosscutting relationships, probably composed by 5
different segments, each representing a short-lived
rapid-flow event (Fig. 15). The individual segments are
characterised by converging heads, attenuated till
lineations and abrupt lateral margins, which indicate
formation by fast flowing ice (ice streams). This is in
agreement with Clark’s (1999) interpretation of the
519
Fig. 16. Suggested correlation of the striae record to the landform
record. Arrows indicate ice flow direction during formation of the
striae sets and fans, respectively. Shaded areas indicate problematic
ice-flow traces (see text).
Ungava Bay landform swarm as representing one or
more rapid-flow events. At least two of the segments are
also verified in the striae record (striae set III). The
suggested interpretation of the south-central part of the
Ungava Bay landform swarm (fan D), as reflecting
multiple events, and the interpretation that fan D
formed before the LGM, imply that the Ungava Bay
landform swarm is unlikely to correlate to the Gold
Cove advance at 9.9 ka.
4.3. Landform systems older that the Ungava Bay
landform swarm
4.3.1. Fan E
Hughes (1964) reported striae observations from the
northwestern part of the Caniapiscau Reservoir, where
northward striae are superimposed on older striae
indicating ice flow towards west–southwest. This observation has traditionally formed the basis for assigning a young deglacial age to the Ungava Bay landform
swarm (e.g. Veillette et al., 1999), but is conclusive if
only one southwestward flow has affected the area. We
show clear evidence (Fig. 9) for repeated southwestward
ice flow (fans A and E). Large drumlins and crag-and-
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K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
Fig. 17. The generalised picture of ice flow evolution in central
Qu!ebec-Labrador (from a to g with increasing age). Lines with
arrowheads indicate ice flow direction and thin lines the approximate
ice surface topography. (a–c) The successive ice marginal retreat
during the last deglaciation (compare with fan A). (d–g) Ice
configuration during the formation of fans B, C, D, and E,
respectively.
tails in the older system, fan E, are often several
kilometres long and are crosscut and degraded by
northward ice flow. The SW-trending fan E lineations
are likewise crosscut by southward deglacial flow in the
Lac Guillemot and Druillon areas (Fig. 8). Due to the
divergent pattern of deglacial ice flow, the large landforms in fan E are aligned to the deglacial flow in the
area northwest of the Caniapiscau Reservoir. Thus, it
appears possible that the southwestward striae described
by Hughes (1964) and the southwestward-trending cragand-tails and drumlins of fan E represent the same
event, in which case these striae only constrain the age of
the Ungava Bay swarm (fan D) to be younger than fan
E, which is currently undated. The southwestward flow
(fan E) is recorded, at several sites, as older than a
southeastward deglacial flow (fan A) and a northward
flow (fan D) east of Lac Avezac by Klassen et al. (1992).
Veillette (1995) reported on north–northeastward
trending striae from the northern and western part of
the Caniapiscau Reservoir area, that predates a west to
west–southwestward ice flow and postdates a westward
ice flow. This chronology indicates that a west to west–
southwestward flow has occurred more than once in the
region. The interpretation of repeated southwestward
ice flow is strengthened by the observation of reverse
chronologies between a northward and a southwestward
flow in the western part of the Caniapiscau Reservoir
(Veillette et al., 1999). Veillette et al. (1999) ‘tentatively’
assume the northward flow to be repeated, but do not
explore the possibility that the SW ice flow may instead
be repeated. The implication of the chronology is that
the northward ice flow, correlated to the Ungava Bay
landform swarm, was not the last glacial event in the
area (cf. Clark et al., 2000). We argue that the youngest
west to west–southwestward ice flow (Veillette, 1995)
correlates to the last deglaciation. The ice flow direction
in the western Caniapiscau Reservoir area during the
last deglaciation is represented by west–southwestward
trending eskers, till lineation features, and ribbed
moraine. The large drumlins and crag-and-tails of fan
E are not aligned to or associated with deglacial
landforms (Figs. 9a and e).
The interpretation of fan E as representing an old ice
flow that predates the last deglaciation is in line with the
interpretation by Clark et al. (2000). Their flow sets FS
16 and FS 17, which correlate to our fan E, is a degraded
system of megalineations (cf. Clark, 1993) of ‘great age’.
Ice flow directions correlative to fan E are also described
(Gray and Lauriol, 1985; Klassen et al., 1992; Veillette
et al., 1999) as older than other ice flows in the region.
4.3.2. Problematic ice-flow traces (Striae set V and NW–
SE trending till lineations)
Striae set V, represented by glacial striae and grooves
indicating ice flow towards ENE in the Lac Rousson
area (Fig. 5), is preserved in lee-side positions relative to
younger striae. The ice flow towards the ENE is not
detected in the till lineation record. However, similarly
directed striae were found in the Lac Avezac area by
Veillette et al. (1999), who interpreted the east–northeastward ice flow to be the oldest, preserved in lee-side
positions of a youngest ice flow towards the NNW and
an ice flow of intermediate age towards SW. We suggest
that the ice flow towards the NNW correlates to fan D,
the ice flow towards the SW correlates to fan E, and that
the ice flow towards the ENE represent the oldest
detected glacial event in the area. The southwestward ice
flow in the Lac Avezac area is by Veillette et al. (1999)
correlated to the radial deglaciation pattern of till
lineations, eskers, and ribbed moraines (our fan A).
However, the eskers 40 km east and south of Lac
K.N. Jansson et al. / Quaternary Science Reviews 21 (2002) 503–523
Avezac, the flights of lateral meltwater channels south of
Lac Avezac (Jansson, unpublished manuscript maps),
and the damming of Glacial lake Chaigneau (Fig. 2)
indicate a southeastward ice flow during the last
deglaciation. This is in agreement with Klassen et al.
(1992) that shows an oldest ice flow towards the
southwest overprinted by a northward flow of intermediate age and a youngest southeastward flow in the
Lac Avezac area. Therefore, we suggest that the
correlation by Veillette et al. (1999) is improper and
that the southwestward striae in the Lac Avezac area
correlate to our fan E, which reflects the oldest coherent
landform system in the area.
The NW–SE trending lineations (Fig. 9f) indicate that
an old flow event, possibly predating all other described
systems, emanated from a dispersal centre SE of the
investigation area. However, the limited number of
lineations does not permit any conclusions about its
former extent.
5. Conclusions
Evidence for at least 5 coherent landform systems are
present in the central parts of Qu!ebec-Labrador. The
landform systems indicate ice flow (with decreasing age)
towards the W/SW, N, NE, E, and SW/S (radial). In
addition, two older landform systems, only present as
scattered striae and till lineations, indicate ice flow
towards ENE and NW, respectively.
The evidence for an extensive older flow towards the
southwest (fan E) allows reconciliation of the interpretation of the Ungava Bay landform swarm (fan D) as
a non-deglacial landform system, and the striae data
(Hughes, 1964) that the Ungava Bay flow is younger
than southwesterly flow in the northwestern part of the
Caniapiscau Reservoir area. The Ungava Bay swarm is
indeed younger than one southwesterly flow event, but
older than the radial flow to which the SW-striae
described by Hughes (1964) have previously been
associated.
Northeast-trending striae and till lineations are superimposed on northward-trending striae and till lineations
(Ungava Bay swarm) in the Caniapiscau Reservoir area.
The northeastward ice flow detected in the Caniapiscau
reservoir area may correlate to and extend the area of
northeastward ice flow previously recorded in the
Schefferville and Lake Attikamagen area. The recognition that ice flow towards the east (fan B) and northeast
(fan C) separate the Ungava Bay flow and the radial
flow, and indicate major dispersal centre shifts between
flow events, further decouples the Ungava Bay flow
from the deglacial phase.
A late southward ice flow north of the Horseshoe
Unconformity is indicated by lateral meltwater channels
and ice margin outlines required for damming of
521
numerous glacial lakes in north-central Qu!ebec-Labrador. The radial flow represents the last glacial event in
central Qu!ebec-Labrador. A U-shaped ice divide did not
exist during the last deglaciation.
Acknowledgements
This study was funded by Swedish Natural Science
Research Council grants to Johan Kleman and grants
from the Swedish Society for Geography and Anthropology, Margit Ahltins fund of the Royal Swedish
Academy of Sciences, Carl Mannerfelts fund, Axel
Lagrelius fund, and Hans Wilson Ahlmanns fund, to
Krister Jansson. These institutions are acknowledged
for their financial support. H. Linderholm assisted in the
field during summer 1999. Clas H.attestrand, Department of Physical Geography Stockholm University and
Arjen Stroeven, Department of Quaternary Geology
Stockholm University gave constructive criticism during
discussions throughout the work. We are grateful to
referees Chris Clark and Andr!ee Bolduc for their helpful
comments that improved this paper.
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