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885
Holocene delevelling of Devon Island, Arctic Canada: implications for ice sheet geometry and crustal response1
Arthur S. Dyke
Abstract: The raised beachesDyke and deltas of Devon Island contain an abundance of dateable materials. A large set of radiocarbon dates (228), 154 of which are new, are used to construct relative sea level curves and isobase maps for the island. The best materials for this purpose are driftwood logs (61 dates) and bowhead whale bones (74 dates) from raised beaches and mollusc shells from marine-limit deltas (20 dates) or from altitudes close to marine limit (14 dates). During the last glacial maximum, the island is thought to have lain beneath the southeastern flank of the Innuitian Ice Sheet. The relative sea level history is congruent with that inferred ice configuration. The island spans half the ice sheet width. Relative sea level curves are of simple exponential form, except near the glacial limit where an early Holocene emergence proceeded to a middle Holocene lowstand below present sea level, which was followed by submergence attending the passage of the crustal forebulge. The response times of relative sea level curves and of crustal uplift decrease from the uplift centre toward the limit of loading, but the change appears strongest near the limit. The Innuitian uplift is separated from the Laurentide uplift to the south by a strong isobase embayment over Lancaster Sound. Hence, ice load irregularities with wavelengths of about 100 km were large enough to leave an isostatic thumbprint in this region of the continent. The apparent absence of a similar embayment over Jones Sound probably indicates a greater Late Wisconsinan ice load there, or a thicker crust than in Lancaster Sound. Résumé : Les plages soulevées et les deltas de l’île Devon renferment une abondante quantité de matériel apte à être datée. Un groupe de nombreuses datations au radiocarbone (228), incluant 154 nouvelles déterminations, a été utilisé pour tracer les courbes du niveau marin relatif et pour dresser les cartes des isobases de l’île. Les matériaux qui fournissent les meilleurs résultats pour cette étude sont les billes de bois échappé (61 âges) et les os de baleine franche (74 âges) dans les dépôts de plages soulevées et les coquilles de mollusques trouvées à la limite marine des deltas (20 âges) ou aux altitudes proches de la limite marine (14 âges). Nous croyons que durant le dernier maximum glaciaire l’île se trouvait sous le flanc sud-est de l’Inlandsis innuitien. L’histoire du niveau marin relatif est compatible avec la configuration déduite de l’étude de l’évolution de l’inlandsis. L’étendue de l’île représente la moitié de la largeur de la calotte glaciaire. Les courbes du niveau marin relatif prennent une simple forme exponentielle, sauf à la limite glaciaire où une émergence durant l’Holocène précoce a entretenu un stade de bas niveau durant l’Holocène moyen en dessous du niveau marin actuel qui fut suivi d’une submergence ennoyant le passage de la zone de bombement crustal. Les temps de réponse des courbes du niveau marin relatif et du soulèvement crustal décroissent en se déplaçant du centre de soulèvement vers la zone limite de charge des glaces, cependant le changement semble avoir été plus rapide à proximité de la limite. Le soulèvement innuitien est séparé du soulèvement laurentidien au sud par un enfoncement prononcé de l’isobase sur le détroit de Lancaster. Donc, les irrégularités de la charge glaciaire avec longueurs d’onde d’environ 100 km, étaient suffisamment importantes pour avoir laissé leur empreinte dans cette région du continent. L’absence apparente d’un enfoncement similaire de l’isobase sur le détroit de Jones indique que la charge glaciaire au Wisconsinien tardif était probablement plus élevée à cet endroit, ou bien la croûte était plus épaisse dans le détroit de Lancaster. [Traduit par la Rédaction] 904
(1970), for example, proposed that the Innuitian Ice Sheet covered the Queen Elizabeth Islands to account for the Much of the discussion of the extent of glaciation during broad, arch-like pattern of regional uplift. A similar, but the Last Glacial Maximum (LGM) in the Queen Elizabeth more qualitative, assessment had been advanced earlier Islands (Fig. 1) has involved postglacial rebound. Blake (Washburn 1947; Wickenden 1947). However, portrayals of the regional pattern of uplift have remained rather fluid, as Received November 29, 1997. Accepted April 1, 1998. reviewed by Dyke (1998). Furthermore, the interpretation of uplift became controversial when advances in the theory of A.S. Dyke. Terrain Sciences Division, Geological Survey of glacioisostasy allowed nonunique ice load distributions to Canada, 601 Booth Street, Ottawa, ON K1A 0E8, Canada explain the uplift pattern. The critical recognition was that (e-mail: [email protected]). ice sheets depress the crust about 200 km beyond their mar- 1Geological Survey of Canada Contribution 1997203; Polar gins because of the stiffness of the crust (Walcott 1970). As Continental Shelf Project Contribution 00298. a consequence, relative sea level (RSL) at an ice margin at
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Fig. 1. Location of the study area (shaded) and principal place names. 120° 60° 84° 84°
RSL CURVES 0 km 300 LR Lyall River Nansen Arctic Sound Ellesmere s BB Bere Bay Ocean nd Island a t sl i I a h r PR Port Refuge et t Greenland ab S liz s E e n r PAB Prince Alfred Bay uee a Q N TB Trito n Bay OP Owen Point PM Providence Mountain Devon LP Lovell Point Island CAP Colin Archer Peninsula Parry Channel Baffin RB Radstock Bay Bay TLI Thomas Lee Inlet Victoria FP Firkin Point Island Baffin CH Cape Hardy Island CB Croker Bay 66° 66° 120° 60°
Norwegian Cornwall Bay Makinson Island Graham Inlet Island 050km Belcher Chan nel Ellesmere Hell Gate Island
Peninsula LR North Kent Simmons Island GrinnellBB N Peninsual Barrow TB South Cape Harbour Colin Archer Fiord PAB Peninsula Goose Cape Sheills Fiord Storm Q Peninsula PR Eidsbotn CAP u Jones Sound e Dundas OP Fiord CH e n Baillie- s Island C Hamilton Viks Thomas Lee h Island FP Truelo ve Bathurst an W Fiord Inlet Baffin ne Sverdrup Lowland l e PM Inlet l l i n Bay g TLI Island t o n Devon Island Cornwallis C h
a Island n LP CB n
e RB Croker
l Maxwell Cuming Viscount Radstock Bay Bay Inlet Melville Gascoyne Bay Barrow Strait Inlet r So und Sound Lancaste Parry Channel t le In y Bylot lt a Prince ir Island Somerset m Borden Prince of Wales Regent Brodeur d Island A Peninsula Island Peel Inlet Peninsula Sound
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equilibrium depression can be on the order of 100 m. Partly dated to the Early Wisconsinan (Klassen 1993; McCuaig for this reason, an alternative interpretation of the 1994). It possibly terminated in an ice shelf in Lancaster postglacial uplift of the Queen Elizabeth Islands was pro- Sound (Dyke and Prest 1987). Similarly, the extent of LGM posed (England 1976a), wherein the Laurentide and Green- ice in Jones Sound remains geologically undefined. How- land ice sheets each depressed swaths of the Queen ever, the RSL data presented below bear importantly on this Elizabeth Islands in their forefields and a series of noncon- question. tiguous intervening ice caps, named the Franklin Ice Com- Deglaciation was underway in the eastern coastal areas by plex, accounted for the rest of the observed crustal 10 000 radiocarbon years BP (10 ka BP). The sea had pene- deflection. Thereafter, the Queen Elizabeth Islands uplift trated to the head of Jones Sound by 9.3 ka BP and to Nor- pattern constituted inadequate proof of the general configu- wegian Bay by 9.2 ka BP. The Wellington Channel coast ration of the LGM ice load (Tushingham 1991; England et was deglaciated about 8.2 ka BP. After clearing of the chan- al. 1991). Indeed, Boulton (1979) even went so far as to in- nels, ice on Devon Island retreated to final remnants scat- sist that the inference of ice sheet configuration from RSL tered along the LGM ice divide. These vanished about 8 ka data, with specific reference to the Queen Elizabeth Islands, BP. The Devon Ice Cap did not disappear during the early was a “misuse of data.” Clearly, therefore, more direct gla- Holocene recession, but it probably shrank to become much cial geological evidence was required to demonstrate what smaller than its present size (Dyke 1998). this configuration might be. A further caution was raised when England (1987; see also England 1997) proposed that neotectonics may have influenced the Holocene uplift pat- tern. Similarly, Dyke et al. (1991) proposed that the strong Methods ridge pattern of early Holocene shoreline deformation over Prior to fieldwork, marine-limit deposits and features the structural Boothia Arch and vicinity indicated a large were mapped from airphotos and the areas of best-developed tectonic complication of the glacial rebound pattern. Be- raised beaches were identified. In the field, elevations were cause no alternative interpretation of that ridge or associated determined by Wallace and Tiernan surveying altimeters us- features has been advanced, we should remain cautious in ing shortest possible closure times between sample sites and assuming that Holocene uplift in glaciated Canada is every- sea level (Dyke et al. 1991). Elevations errors are no more where a simple glacioisostatic response. than 5%. In a companion paper, I have argued entirely from ice- A variety of materials was collected for radiocarbon dat- flow and ice-recession evidence that the Innuitian Ice Sheet ing. Marine mollusc shells proved to be the most abundant model is appropriate for at least the southeastern Queen fossils associated with marine limit. Shells from 20 marine- Elizabeth Islands (Dyke 1998). One purpose of this paper is limit deltas and a further 14 collections found closest to lo- to demonstrate that the postglacial rebound pattern in this re- cal marine limits have been dated. Several samples of shells gion is also congruent with the Innuitian model. If this is ac- and terrestrial plant detritus from perched deltas below ma- cepted, the door is open for inverse modeling of RSL rine limit were also dated. Sixty-one samples of driftwood histories as the most economical way of reconstructing the and 74 samples of bowhead whale (Balaena mysticetus) ear ice thickness history from LGM onward for the Queen Eliz- bones from raised beaches were dated. Several walrus abeth Islands in general. This would be a useful guide for (Odobenus rosmarus) tusks from raised beaches were also the next phase of research in regional glacial geology. RSL dated, but some of these are evidently from animals that history is reconstructed herein from 228 radiocarbon dates, wandered inland and died. Ages of archaeological sites and 154 of which are previously unpublished. The Devon Island a few basal peat deposits further constrain RSL interpreta- RSL data are of further interest, because they record the tions. crustal response to unloading from the centre of uplift to All pertinent radiocarbon age determinations are reported near the edge, and because well-constrained RSL curves al- in Appendix 1, Table A1. Age determinations for terrestrial low an evaluation of curve forms, response times, and δ13 materials are normalized to CPDB = –25‰. Shell dates are forebulge migration. reported with a –400 year marine reservoir correction after the same normalization. Bowhead whale bone collagen ages are reported in uncorrected form along with the δ13C mea- surements. In effect, this applies a reservoir correction of Devon Island extends halfway across the Queen Elizabeth about –200 years, which seems appropriate on the basis of Islands from Baffin Bay in the southeast toward the Arctic comparative datings of wood and bones and other criteria Ocean in the northwest (Fig. 1). In Blake’s (1970) original (Dyke et al. 1996). Subjective RSL curves (not presented) proposal, the western tip of the island lies near the centre of were drawn using all available data. Samples that poorly the Innuitian Ice Sheet. The glacial geology of Devon Island constrain the curve (e.g., a deep-water shell dates) were re- and vicinity indicates that ice flow from the central part(s) moved and least-squares regressions were fitted to the re- of the Innuitian Ice Sheet and convergent flow from an ice maining data. divide over the axis of Devon Island, and possibly from Cornwallis and Bathurst islands, sustained an ice stream in Marine limits Wellington Channel at LGM. This ice stream extended along A local marine limit can be recognized with certainty Lancaster Sound an undetermined distance beyond Gas- where the highest marine features coincide with the lowest coyne Inlet. It presumably ended short of the Eclipse Mo- contemporaneous subaerial features. On Devon Island, this raines at the mouth of the sound because these have been condition is met in many places where ice-marginal (lateral)
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Fig. 2. Marine-limit elevations in metres. Fig. 3. Marine-limit ages in thousands of radiocarbon years BP.
100 km 100 km Marine limit elevation (m) Marine limit age (ka)
7.8 jord 98+ 131 101 r F 8.8 114 thu 8.8 99 Ar 8.6 8.6 116 8.5 9.0 80 110 8.3 8.4 91 120 8.2 8.7 95 120 Cape 9.3 Hardy 8.6 104 8.2 84 100 114 > 9.4 Thomas Lee 6 110 Inlet 8.6 8.8 94 8.1 78 77 80 7.9 8.2 8.2 83 81 102 8.5 74 48 8.9 9.1 102 8.8 79 0 8.7 90 8.6 26 >8.0 8.9 65 56 42 38 8.8 9.9 91 56 9.1 8.8 106 115 R 9.5 ad sto ck Bay
meltwater channels descend to the highest raised beaches ples that are closely associated with RSLs. The new radio- and where ice-contact or ice-proximal deltas occur, com- carbon dates reported here provide RSL curves for 13 addi- monly at the mouths of meltwater channels. tional sites as well as an additional date for Radstock Bay The marine-limit elevation varies strongly across Devon (Appendix 1, Table A1; Fig. 4). The samples for most of Island (Fig. 2). Raised beaches on northwestern Grinnell these RSL curves were collected within radii of 10–15 km. Peninsula extend to 131 m altitude and are among the high- These curves, therefore, represent small areas within which est in the Queen Elizabeth Islands. In contrast, Late there is limited isostatic tilting. Such curves are much better Wisconsinan lateral meltwater channels extend down to the than most previous curves available from the southern modern beach on the southeastern part of the island. A Queen Elizabeth Islands which were derived from widely strong northward component of tilt is illustrated by the high dispersed samples, commonly from an entire island or island marine limit of 114 m near Cape Hardy, here marked by group (e.g., Walcott 1972; Dyke et al. 1991). The new perched outwash terraces superimposed on their slopes by Devon Island curves are among the best quality RSL curves beaches. These gross variations in marine-limit elevation available for Canada. The curves are of two basic types: primarily reflect isostatic tilting, but the age of marine limit those illustrating continuous emergence (here designated ranges from about 10 ka BP to 8.2 ka BP (Fig. 3). Thus, the “western” curves), and those illustrating emergence followed highest marine limits in the west are substantially younger by a stable RSL or by submergence (intermediate and east- that the lower limits in the east, and the marine-limit gradi- ern curves). ent in that direction is a dampened expression of crustal In the Canadian High Arctic, the best materials for radio- delevelling. carbon dating of raised beaches are driftwood and bowhead More local variations in elevation are also normal charac- whale remains, because both wood and dead bowheads float teristics of marine-limit “surfaces;” they result from emer- and have a good chance of coming to rest on their contem- gence during locally protracted ice recession (e.g., Andrews porary beaches. These are the main materials dated from 1970). On Devon Island, the most significant local varia- Devon Island (135 dates; Appendix 1, Table A1). Although tions are as follows: (i) marine limits are lower along central sea-ice push can cause vertical displacement of these materi- Wellington Channel than at either end; and (ii) marine limits als, wave pitching of wood is minimal in the Queen Eliza- decline inland along certain inlets, e.g., Radstock Bay (115– beth Islands because of the brief open-water season and 65 m), Thomas Lee Inlet (102–79 m), and Arthur Fiord short wave fetches. Accordingly, dated driftwood series (110–80 m; Fig. 2). Dyke (1998) presented a map of the from the Queen Elizabeth Islands lack the problems evident, deglaciation pattern based on ice-marginal landforms, and for example, in the series from southeastern Hudson Bay these local variations in marine-limit elevations are accor- (Allard and Tremblay 1983). Wood on the surface of a dant with that pattern. raised beach is less satisfactory than embedded wood be- cause of the risk that it has been moved by either natural Relative sea level curves processes (sea-ice push, wind, streams) or by people. Never- In the southern Queen Elizabeth Islands, well-constrained theless, in most cases, surface wood gives accordant ages. RSL curves are available only for Cape Storm and South The sources of error in these sorts of data were reviewed by Cape Fiord (Blake 1975); a less constrained curve is avail- Dyke et al. (1991) and assessed to be symmetrical about the able for Makinson Inlet (Blake 1993). RSL curves have been true RSL. This means that these data can be legitimately fit- published for Truelove Lowland, northeastern Devon Island ted by regression techniques. In contrast, most series of ma- (Müller and Barr 1966; Barr 1971; Dyke et al. 1991; King rine mollusc dates should not be fitted by this or similar 1970, 1991), for Grinnell Peninsula (Grosswald 1983), and means, because this places half of the samples above the for Radstock Bay, southwestern Devon Island (Dyke et al. curve and the animals out of the sea at the time they were 1991). These curves are not well controlled by dated sam- living. In Canada, only curves from the Arctic Islands are
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Fig. 4. Least squares regression RSL curves for 14 sites on Devon Island. The data points for negative RSLs in Fig. 4O are based on extrapolation of shoreline gradients from Fig. 6. Site abbreviations as in Fig. 1. Lyall River Exponential Regression Bere Bay Exponential Regression 140 120 (A) (B) 120 LR 100 BB 100 80 80 60 60
RSL (m) 40 40 RSL (m) 20 20
0 0
0 2 4 6810 0 2 4 6810 Radiocarbon years BP x 1000 Radiocarbon years BP x 1000
Port Refuge Exponential Regression Prince Alfred Bay Exponential Regression 120 100 (C) (D) 100 80
80 PR 60 PAB 60 40 RSL (m)
RSL (m) 40 20 20
0 0
0 2 4 6810 0 2 4 6810 Radiocarbon years BP x 1000 Radiocarbon years BP x 1000
Triton Bay Exponential Regression Owen Point Exponential Regression 120 100 (E) (F) 100 TB 80 80 60 OP 60 40 40 RSL (m) RSL (m) 20 20
0 0
0 2 4 6810 0 2 4 6810 Radiocarbon years BP x 1000 Radiocarbon years BP x 1000
Colin Archer Exponential Regression Providence Mountain Power Regression 140 100 (G) (H) 120 80 100 CAP 60 PM 80
60 40 RSL (m) 40 RSL (m) 20 20 0 0
0 2 4 6810 0 2 4 6810 Radiocarbon years BP x 1000 Radiocarbon years BP x 1000
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Fig. 4 (concluded). Lovell Point Exponential Regression Radstock Bay Exponential Regression 100 140 (J) (I) 120 80 100 60 80
40 60 LP RB RSL (m) RSL (m) 40 20 20 0 0
0 2 4 6810 0 2 4 6810 Radiocarbon years BP x 1000 Radiocarbon years BP x 1000
Thomas Lee Inlet Exponential Regression Firkin Point Exponential Regression 100 35 (L) (K) 30 80 25 60 FP TLI 20
40 15 RSL (m)
RSL (m) 10 20 5 0 0
0 2 4 6810 0 2 4 6 8 10 Radiocarbon years BP x 1000 Radiocarbon years BP x 1000
Cape Hardy Exponential Regression Croker Bay Quadratic Regression 70 60 (M) 60 (N) 40 50 CH 40 20 30 CB RSL (m)
RSL (m) 0 20
10 -20 0
-40 0 2 4 6810 0 2 4 6 8 10 12 Radiocarbon years BP x 1000 Radiocarbon years BP x 1000
Croker Bay Cubic Regression 50 (O) 40 y= 0.0987 x -1.5320x23 + 0.1904x r2 = 0.966 30
20
10 RSL (m)
0 CB
-10
-20 024 6 8 10 12 Radiocarbon years BP x 1000
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Dyke 891 transgression possible 4ka before 3 ka too low Similarity ) 2 bx + 2 ax + o y ve curves and with the highest coefficients = y –0.0764 1.1913 0.974 Similar; too low last –0.0827 0.9378 0.907–3.7562 Too low throughout 1.7487 0.985 False late transgression –7.9087 1.8624 0.969 False late transgression –5.7550 1.1775–15.7180 0.902 1.9405 Similar; too low 0.932 Very similar; lowstand abr last3ka overestimates marine limit age last4ka last5ka low 3–6 ka conditioned Similarity 2 ) Quadratic ( b ax = y 1.2859 1.9922 0.9701.6531 Similar 1.8532 0.980 Similar; too low 1.6248 –1.2328 1.7581 0.926 1.3482 Too low 0.953 last 2 Too ka; low last 5 ka 0.0000 9.9202 0.926 Array ill 0.0001 6.3853 0.919 Too low last 8 ka –8.3110 1.8293 0.892 False late transgression abr inter- inter- y y cept 3 m last2ka cept 3 m last6ka ka (ka) Similarity ½ 1.61 Very1.768 similar Very similar2.011 0.4084 2.6020 Similar; 1.867 0.6225 0.977 2.3673 Similar Similar; too 0.988 high Very1.532 similar Similar2.059 –4.3846 –4.1967 Similar; 1.9483 1.77451.934 0.968 0.960 0.1338 False Very False 3.0752 late similar late transgression transgression 0.9321.744 Too low last 0.5024 5 Similar ka 2.4521 0.990 –7.21331.785 Similar; too 2.0007 low Very similar 0.859 1.5521 False late 1.8583 transgression 0.1664 0.9991.245 2.7471 Very similar 0.954 Very similar Too low last 51.623 ka 0.0076 0.7713 –4.2109 Very similar 4.2603 1.0573 1.2267 0.9951.113 0.999 0.894 Similar; too 0.0937 low Very Very False similar similar late0.647 2.7675 transgression 0.962 Stable RSL Very similar 0.0004 5.3876 0.978 Very similar; –1.8623 too 0.6773 0.949 Similar; slight late 0.680 Too low last 8 T =8) = 14) =9) = 20) = 10) = 14) =7) =4) = 14) =5) = 15) = 12) = 19) =6) n n n n n n n n n n n n n n ) Power ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( bx 2 e a = y abr 2.7182 0.4303 0.982 3.4895 0.3919 0.991 5.0930 0.3446 0.984 3.9178 0.3694 0.981 2.1234 0.4523 0.944 4.3556 0.3365 0.941 4.3338 0.3583 0.991 2.9696 0.3973 0.995 2.1848 0.3882 0.966 0.6003 0.5566 0.994 0.9820 0.4269 0.968 0.1783 0.6222 0.983 0.0009 1.0705 0.923 Exponential ( 0.0077 1.0183 0.949 Results of least squares regressions of RTSL data for 14 curves on Devon Island. Comments in the Similarity columns describe the similarity of the regression to the subjectively drawn curve. The curves most similar to the subjecti a Subjective curve used for isobase maps. (Fig. 4A) (Fig. 4B) (Fig. 4C) Bay (Fig. 4D) (Fig. 4E) (Fig. 4F) Peninsula (Fig. 4G) Mountain (Fig. 4H) (Fig. 4I) Bay (Fig. 4J) Inlet (Fig. 4K) (Fig. 4L) (Fig. 4M) (Fig. 4N) Notes: a Table 1. RSL curve Lyall River Bere Bay Port Refuge Prince Alfred Triton Bay Owen Point Colin Archer Providence Lovell Point Radstock Thomas Lee Firkin Point Cape Hardy Croker Bay are shown in Fig. 4.
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well dated by driftwood and whale bones. Therefore, oppor- Nevertheless, we need to consider whether the assumption tunities to objectively define the forms of RSL curves are that RSL curves have a smooth form might preclude the rec- limited. ognition of brief oscillations of sea level. It could be argued, for example, that the scatter of dates in the individual RSL Western curves curves of Fig. 4 results from multiple, small (generally Despite the large number of age determinations, no RSL <4 m) transgressions. To test this, assume that the true RSL curve in this group is ideally constrained by dated samples. curve passes through every sample. In doing this, I found 22 However, where dating control is adequate, there is little putative transgressions between 1.0 and 6.8 ka BP, occupy- reason to suspect that the true form of regional RSL change ing more than 50% of the time interval (data not presented is anything other than a simple, exponentially declining but derivable from Fig. 4). Thirteen of these (60%) occur at emergence rate. Least-squares regression fits are good (r2 = only one site, three are recorded at two sites, and one at 0.941 to 0.995), using either a two-parameter power function three sites, lumping events into 0.2 ka bins. None of the pu- (y = axb, where y is elevation (in m), x is age (in ka), and a tative events fall in the interval 4.8–5.4 ka BP (see below). and b are constants that yield the least-squares fit), or an ex- This random distribution indicates that the scatter in the data ponential function (y = aebx, where e is the base of natural is not due to transgressions. logarithms; Table 1). The exponential function yields No convincing evidence of middle or late Holocene trans- slightly, but consistently, higher coefficients of determina- gressions has been reported from the generally rebounding tion (r2) than does the power function, and in general it part of the Queen Elizabeth Islands. Stratigraphic evidence, closely resembles the subjectively drawn curves. For most in particular, is entirely lacking. Blake (1970, 1975) consid- exponential curves, the y intercepts are close to zero without ered the case for a transgression at 5 ka BP to account for a being forced through the origin. There is, however, a distinct concentration of pumice on a well-developed beach of that tendency to slightly underestimate the emergence rate for the age on southern Ellesmere Island. He concluded, as did last 2–4 ka. This and the slightly “erroneous” y intercept Walcott (1972), that the evidence for it is equivocal and that could be due to the action of waves and sea-ice push dis- any transgression that might have occurred was probably placing the driftwood and bones a metre or so above the less than 2 m and shorter than 0.5 ka. More recently he has stranding line. Dyke et al. (1991) reached the same conclu- tentatively proposed a slight transgression or stable RSL at 5 sion from similar evidence from Prince of Wales Island. The ka BP at two sites on eastern Ellesmere Island (Blake 1993, reason for not forcing the curve through the origin is to al- his Figs. 10 and 12). The evidence for it is the scatter in a low an objective assessment of the possible influence of few dated samples at each site which therefore is of the these natural sources of error. same nature as that considered above for Devon Island. For this western group of curves, a quadratic polynomial 2 regression (y = y0 + ax + bx ) generally yields high, but somewhat lower, coefficients of determination (Table 1). Eastern curves However, most of these regressions depart more from the The easternmost part of Devon Island has experienced net subjective curves than do the other fits, and in several cases transgression during the Holocene (Fig. 2). No curve is they generate unrealistic late Holocene transgressions (com- available from this area and no submerged coastal or terres- ments in Table 1). Expressions with more parameters than trial features have yet been sought. Where marine limits are those presented generally prove to be overparameterized, as low in the east, as at Croker Bay (Figs. 1, 2, 4N, and 4O), an indicated by dependencies near 1. initial phase of emergence was followed by a middle Holo- The Radstock Bay data (Fig. 4J) are not well fitted by any cene lowstand and a late Holocene transgression. The initial of the expressions considered (Table 1). Because these ex- emergence limb of the Croker Bay curve is well defined by pressions well describe the other curves, there may be errors 19 age determinations on bowhead whale ear bones. The of measurement or interpretation in the current Radstock oldest of these (9.92 ka BP) is a closely limiting date on ma- Bay data set. This curve is not discussed further. rine limit (37.5 m). The set of dates is nicely accordant (lit- The strongest suggestion of a more complex RSL history tle scatter), and the lowest datable raised beach (3 m) is >8 in the western area is a possible halt or minor transgression ka old. at about 2.25 ka BP at Prince Alfred Bay (Fig. 4D). How- The modern beach at Croker Bay is distinctly different ever, this suggestion relies on only two samples that lie from the raised beaches. The raised beaches are mostly 0.5– slightly farther above the curve than others, and these may 1 m thick, with comparable ridge to swale relief; the modern simply result from sea-ice push at or shortly after stranding. beach has a relief and apparent thickness of up to 4 m and it Both samples were small pieces of driftwood that were not isolates lagoons that are characteristic of a transgressing embedded in the raised beaches. No other curve in this shoreline. Much of easternmost Devon Island has a barrier- group shows signs of a halt or a transgression at this time, beach coastline that is reminiscent of classical submerging and no stratigraphic or morphological evidence of a trans- coasts such as those of the Gulf of St. Lawrence. gression at this or any other time during general emergence The Croker Bay data are best fit (r2 = 0.932) by a qua- was observed on Devon Island (Figs. 4A–4K). The author’s dratic polynomial expression constrained to pass through the impression, from many surveys of raised beaches in the origin (Table 1). This fit predicts that emergence continued Canadian Arctic, is that those beach ridges which are to about –30 m at 4.5 ka BP (Fig. 4N). No empirical data are strongly developed can usually be explained by their topo- available to test this. Nevertheless, it is improbable that RSL graphic position or by factors affecting sediment supply, has risen by 22 m in the last 2 ka, as this quadratic fit pre- rather than by transgressions. dicts. Therefore, the middle Holocene lowstand is not likely
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Fig. 5. Response-time parameters vs. amplitude parameters for Devon Island RSL curves. Site abbreviations as in Fig. 1. 2.0 (A) 5 PR (B) -18 (C) bx 2 Y= axb Y= ae Y= Yo+ax+bx OP CB PAB CAP 1.6 PM 4 -14 PAB
BB PR 1.2 3 PM -10
ameter (a)
ameter (a) LR
ameter (a)
LP TB 0.8 2 -6 CH
BB
Amplitude par
Amplitude par CAP Amplitude par 0.4 LR 1 FP -2 FP
TLI PAB 0 TB RB+CH RB+CB PM FP TLI CH CH 0 +2 0 2 4 6 0.3 0.40.5 0.6 0.8 0.5 1.0 1.5 2.0 Power of time (b) Multiple of time term (b) Multiple of time term (b)
½ to have reached –30 m. The depth of this lowstand is as- (Fig. 5B). The half-life (T )isloge 2/b (e.g., Andrews sessed further below. 1970), and these values are listed in Table 1. The e-folding time, or exponential relaxation time, a parameter more com- Intermediate curves monly used by geophysicists, is 1/b or 1.44T½. T½ is about Marine limits along the northeast coast are higher than 2 ka for sites near the uplift centre. Specifically, for three those along the southeast coast, and the two new curves adjacent sites, it is 1.876 ka at Prince Alfred Bay, 2.011 ka from the northeast coast are of a form intermediate between at Port Refuge, and 2.059 ka at Owen Point. The small dif- the eastern and western curves. On the Cape Hardy lowland ferences between these values are probably due to imperfect (Fig. 4M), RSL had dropped to within a couple of metres of dating control. T½ decreases to 1.113 ka at Cape Hardy, the present by 3.5 ka BP, according to an age determination on most easterly curve that has an exponential form. If an expo- one of the lowest raised beaches (Appendix 1, Table A1). At nential curve is used to approximate T½ of the Croker Bay Firkin Point (Fig. 4L), farther west, RSL was no more than site, the result is 0.647 ka. However, this should be regarded 4 m above present at that time. These curves, which are well as a minimum estimate, because emergence continued below fit by either of the expressions listed in Table 1, indicate that present sea level here. Croker Bay data are best fit by a qua- RSL has been nearly stable for the last 2–3 ka and a slight dratic function, which also produces a reasonable fit to the transgression may have commenced at Cape Hardy. Cape Hardy data. The results confirm that the response time continues to decrease (b gets larger) between Cape Hardy Response times of RSL and uplift curves and Croker Bay, which is in the direction of lesser loading. The two parameters in the regression equations describe The response times of these RSL curves do not accurately the amplitudes (a) and response times (b) of the RSL curves. represent the response times of crustal uplift, because no The curve sites are distributed along a transect from an ice correction is applied for eustatic sea level change and be- sheet, and an uplift, centre to near its limit, but most are cause radiocarbon time deviates from sidereal time. There- close to the centre. The response time evidently decreases fore, we need to consider whether the differences between with distance from the centre but the change seems to be the response times of these curves are due to the variable concentrated near the limit (Fig. 5). Plots of amplitudes ver- corrections that ought to be applied to them. Unfortunately, sus response-time indices for the power function, for exam- there is still no entirely satisfactory way of converting an ple (Fig. 5A), indicate that elevation varies roughly as the RSL curve to an uplift curve, because there is no single ap- square of time at the centre (b = 2) but as the cube of time plicable “eustatic correction,” on account of the (faster) farther east, and as the fifth power of time at Cape hydroisostatic deformation of the ocean basins. Indeed, the Hardy, the most easterly curve that is reasonably described practice of “eustatically correcting” RSL curves has been by this function. The Croker Bay curve has an even shorter largely abandoned for this reason (e.g., Andrews and Peltier response time, but it is not realistically described by this 1989). Furthermore, there is no unique conversion from ra- function. diocarbon to sidereal time. A similar decrease of response time with decreasing am- Nevertheless, we can examine whether the differences in plitude is seen in the parameters of the exponential function response times discussed above remain after approximate
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corrections are applied. Accordingly, two of the better-dated load remains uncompensated. The substantial transgression RSL curves (Prince Alfred Bay, west; Cape Hardy, east) on southeast Devon Island, therefore, is more probably due were recalculated after applying the eustatic corrections in- to inward migration of the glacial forebulge. dicated by the recent Barbados RSL curve (Fairbanks 1989) and after converting the radiocarbon ages to calendar years Isobase maps using CALIB3 (Stuiver and Reimer 1993). The T½ of the Isobase maps for the Devon Island region (Fig. 6) are Prince Alfred Bay “uplift” curve is 1.870 ka (6 years less) based on the RSL data in Appendix 1, on published curves and T½ of the Cape Hardy “uplift” curve is 1.219 ka (106 for adjacent sites (Blake 1975, 1993; Dyke 1979, 1983, years more). Thus the difference is reduced by only 15%, 1993; Washburn and Stuiver 1985), and on the author’s un- and the T½ of the Prince Alfred Bay RSL curve is on the low published curves for northern Baffin Island. The unpub- side of the value of this parameter for central sites. lished Baffin Island data extend much farther south than the In evaluating the form of a true uplift curve, the amount area covered in Fig. 6 and are continuous with the data pre- of rebound that has yet to occur, so-called residual rebound sented by Hooper (1996). These data have guided the lines (Andrews 1970), must also be considered. The residual re- along the south side of Lancaster Sound. The “submerged” bound at Cape Hardy is negligible, because RSL has part of the Croker Bay curve was not used, and subjective changed imperceptibly there during the last 3 ka. The curves were used where regression fits are poor (i.e., amount of residual rebound at the uplift centre is calculated Radstock Bay; Fig. 4J). The 10 ka BP shoreline (Fig. 6A) is below as 6.25 m over the next 4 ka. When this quantity is defined for only the eastern part of the region, and only lim- included in the total postglacial uplift curve for Prince Al- iting values, the altitudes of younger marine limits, can be fred Bay, that is, a curve with sea level at0m4kainthefu- assigned to the change of elevation since 10 ka BP else- ture and the present shoreline raised to 6.25 m, T½ for this where. However, the 9 ka BP and younger shorelines site increases to 2.251 ka. Because the value for Cape Hardy (Figs. 6B–6Hh) are defined across the region. remains unchanged, the difference in T½ between Cape The pattern of shoreline delevelling in this region is sim- Hardy and Prince Alfred Bay is increased by nearly 0.4 ka. ple and involves two elements (Figs. 6A–6H): (i) a rise of Hence, it appears that the decrease of T½ from the centre of shorelines of all ages from southeast to northwest, and (ii)a uplift toward the margin is a persistent feature of the data. prominent embayment of the isobases over Lancaster Sound. Geophysicists have long described postglacial uplift as a The northwestward rise of shorelines defined by the new simple exponential function (y = aebx) and have pointed out RSL data from Devon Island confirms the general that b, the proportionality constant, is related to mantle vis- delevelling pattern presented by Blake (1970, 1975), on cosity and to the size of the ice sheet (e.g., Andrews 1970, which he based the proposition of an Innuitian Ice Sheet. πη p. 37, cites a simple early model: b =(Pmg/2 )L, where Pm This contrasts with the east–west alignment of isobases is mantle density, g is acceleration due to gravity, η is mantle along the south coast of Ellesmere Island as portrayed by viscosity, and L is an ice sheet scale factor; this has been England (1976a, 1976b) in his argument for an alternative superceded by more elaborate models (Tushingham and glaciation model. Peltier 1991)). Using what in retrospect was a sparse RSL The isobase embayment over Lancaster Sound separates data set, mainly shell dates, Andrews (1970) found that the the uplift domains of the Laurentide and Innuitian ice sheets. proportionality constant of Canadian Arctic uplift curves Its prominence supports the argument that the Late was essentially invariant. However, most of the data used in Wisconsinan Innuitian Ice Sheet was dynamically independ- that analysis were from heavily ice loaded sites; that is, sites ent of the Laurentide Ice Sheet, though they apparently co- with appreciable recent and ongoing uplift. The Devon Is- alesced as grounded ice in Barrow Strait (Fig. 1). One land RSL curves also indicate closely similar response times significance of this embayment is that ice-load irregularities at such sites. However, the evident decrease in response on this scale (100 km wide) may be reflected in crustal times near the ice sheet limit seems to be a novel feature of delevelling patterns where the database is adequate. Similar the Devon Island data. The geophysical implications of this isobase embayments occur along Hudson Strait and the Gulf finding deserve attention, and further scrutiny of RSL histo- of St. Lawrence (Dyke 1996). ries near glacial limits is warranted to see if the pattern is The extent of grounded ice in Lancaster Sound at LGM is spurious, regional, or general. Perhaps the shorter uplift not well constrained geologically. Some or all of the depres- half-lives of sites near the limit of ice loading, where total sion within the sound may have been due to peripheral de- crustal depression was small, reflect a dominance of control pression from the terrestrial ice loads and from grounded ice by the properties of the more elastic crust, and the longer in Barrow Strait. Whatever ice load disappeared from Lan- half-lives of central sites, where depression was large and caster Sound was partly replaced by the present water load. involved a greater volume of displaced mantle, reflect a The strong isobase embayment over the sound signifies that dominance of control by properties of the mantle. the excess of LGM ice load over present water load was less The unquantified late Holocene regrowth of the Devon Ice than the ice load over the adjacent land. Cap (Fisher 1979; Dyke 1998) may have partly countered The seeming absence of a similar isobase embayment the rebound from earlier deglaciation. Part of the late Holo- over Jones Sound allows an evaluation of the LGM ice load cene transgression at Croker Bay may thus be due to this re- there. The straight isobases across Jones Sound are not loading. However, the contrast between the south and north likely due to a poor distribution of data, because the shore- sides of the ice cap (Croker Bay versus Cape Hardy) sug- line elevations on the north coast of Devon Island are con- gests that late Holocene reloading has had a minor effect sistently intermediate between those on the south coast of and, given millennial response times, much of the new ice that island and those on the south coast of Ellesmere Island.
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Fig. 6. Isobase maps of the Devon Island region. Points A and B in Fig. 6A delimit the shoreline profiles of Fig. 7.
>120 100 km 100 km A 10 ka 9 ka ~100 60 140 120 100 80 60 20 80 140 120 40 >131 ~150 >100 120 20 >120 -20 >101 >10 0 ~100 >120 ~10 >110 >120 >110 >130 >100 ~100 >115 0 >90 95 55 75 55 > 80
>102 >102 85 70 < 0 < 0 B >90 >56 41 20 38 55 0 >115 ~100 90-100
72 > 24 40 52 >24 40 84 40 (A) > 57 62 (B) 99 52 45 52
100 km 70 100 km 80 70 8 ka 60 7 ka 50 60 30 40 20 90 40 30 20 95 10 62 50 10 84 58 80 70 60 35 80 9 55 0 54 45 75 0 50 70 30 -10 80 54 20 70 30 45 25 -10 30 20 70 50 30 < 0 < 0 > 40 2 45 -10 30 -3 64 42 40 0 58 41 -10 0 28 18 20 10 0 54 42 2 30 31 20 (C) 30 20 32 (D) 32 22 5 26
100 km 25 100 km 6 ka 40? 5 ka 24 28 8 40 20 36 32 24 20 16 4 40 40 16 4 25 0 41 27 18 -4 26 3 28? 20 21 22 30 12 8 23 0 28 40 35 24 12.5 7 40 35 15 27 26 10 12.5 -4 24 8
15 10
22 < 0 17 < 0 -4 21 0 17 32 25 0 < 0 8 0 < 0 < 0 < 0 8 24 16 20 12 (E) 26 18 19 (F) 20 16 < 0 14
16 100 km 4.5 100 km 4 ka 2 ka
12 6 4 2 8 0 7 -2 15 20 4 0 6.3 3 20 10 -4 18 14 8 6 5 21 15 8 5 19 7 20 8 8 18 2.5 0 6 2 18 5 7 0 6 2
< 0 < 0 13 5
-2 12.5 -4 4 18 0 7 < 0 < 0 < 0 4 8 < 0 < 0 0 2 8 7 4 (G) 16 12.5 < 0 7.5 (H) 2
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Fig. 7. Shoreline profiles along line A–B (see Fig. 6A). falls inboard of the uplift margin and its migration reflects the combined effects of eustatic rise and migration of the ABkilometres 100 200 300 400 500 600 forebulge. In the late Holocene, the latter effect dominates. A proper determination of changes in radius of the uplift
140 would require RSL curves with dated submerged shorelines east of Croker Bay. 130 The position of the zero isobase in earliest postglacial 120 time is defined by the zero contour on marine-limit elevation
110 (Fig. 2). Thereafter, its position can by estimated by extrapo- lation of the delevelled shoreline gradients (Fig. 6). The time 100 of its migration through formerly uplifted sites that are pres- 9 ka 10 ka BP 90 ently submerging can be read from RSL curves such as the 8 ka one for Croker Bay (Fig. 4). Between 9 and 2 ka BP, the 80 Uplift centre zero isobase progressively shifted 220 km westward along 70 Lancaster Sound (Figs. 6B–6H). In doing so, it crossed the
60 7 ka entire Devon Ice Cap area. Although the Neoglacial
Elevation (m) Elevation regrowth of the ice cap has probably contributed to late Ho- 50 locene submergence of eastern Devon Island, this cannot 40 6 ka presently be separated from the systematic shrinkage in the radius of the Holocene uplift. 30 5 ka 4 ka 20 Middle Holocene lowstand 10 2 ka The isobase maps provide an additional means of assess- 0 ing the amount of late Holocene submergence that has oc- curred at Croker Bay. Assuming a consistent spacing of -10 isobases beyond the lowest portrayed, the RSLs at Croker Bay are as follows: –16 m at 6 ka BP, –10 m at 5 ka BP, –14 m Furthermore, the lack of deflection of isobases across Jones at 4 ka BP, and –5 m at 2 ka BP (Figs. 6E–6H). These are Sound cannot be ascribed to the width of the sound, because slight overestimates, because shoreline gradients should pro- it is as wide as Lancaster Sound. If the crust under Jones gressively decrease toward the margin of the uplift. Never- Sound is considerably thicker than it is under Lancaster theless, the isobase maps thus yield more conservative and Sound, the isostatic effects of regional ice loads in and more realistic predictions, particularly for the last 4 ka, than around Jones Sound would have been more attenuated. Thus does the RSL curve of Fig. 4N. Although these predictions any regional contrasts in ice thickness might be muted in the cannot be considered primary data, they are based on data isobase pattern. However, if crustal thicknesses are similar, from neighbouring sites. and we have no evidence that they are not, the ice load in When these four estimates are added to the Croker Bay Jones Sound was probably greater than that in Lancaster RSL series, the quadratic polynomial expression provides a Sound. That inference is significant, because the ice config- lower coefficient of determination (r2 decreases from 0.932 uration in Jones Sound is poorly constrained otherwise. If an to 0.802) and the fit (not presented) to the early Holocene ice stream filled Jones Sound, then ice thicknesses north of raised-beach data becomes unrealistic: all samples fall above it on Ellesmere Island were substantially greater than those the curve. The extended series, however, is well fitted by a south of it on Devon Island. Possibly there was no ice cubic polynomial expression with r2 of 0.966 (Fig. 4O). stream, and instead the sound was filled, or nearly filled, by ice from both sides, but with Ellesmere ice dominating. A better definition of ice loads in these sounds can be best Shoreline profiles and the uplift centre achieved through uplift modeling. The best replication tar- Shoreline profiles (Fig. 7) are drawn along the 600 km gets for inverse modeling of ice sheet history from RSL data transect A–B (Fig. 6A). For the 8 ka BP and younger shore- are isobase maps. They portray a spatially continuous re- lines (Figs. 6C–6H), this profile represents one entire side of sponse, they allow identification of outlier (misfit) data that the Innuitian uplift. However, the uplift centre at 9 and 10 ka might not appear anomalous on any RSL curve of average BP, and presumably earlier times, appears to have been posi- quality, and they incorporate the full RSL database, not just tioned northwest of point A. Extrapolation of the shoreline those spatially clustered samples which define RSL curves. profiles places the uplift centre at 9 ka BP about 100 km For modeling purposes a complete time series of isobase northwest of point A; at 10 ka BP, it presumably was at least maps, as in Figs. 6A–6H, is best. that far northwest. Accordingly, the Innuitian uplift centre migrated at least 250 km southeastward before 6 ka BP. This The zero isobase implies that the LGM maximum ice thickness, which in this The zero isobase separates areas of emerged and sub- topographic setting of low islands and wide, shallow chan- merged paleoshorelines. It is thus a proxy of changes in the nels would coincide with the ice dome or ice divide position, radius of an uplift. It is only an approximation, because was also northwest of point A. If so, the dome or ice divide early in postglacial time eustatic sea level rise outpaced slow was located quite asymmetrically within the Queen Eliza- uplift at distal sites. Hence, the zero isobase for these times beth Islands. In turn, this carries implications for the loca-
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tion of the glacial limit along the polar margin of the scale transgressions during general Holocene emergence is archipelago. significant and is consistent with other results from the cen- The migration of the uplift centre also suggests that the tral and eastern Canadian Arctic, where only equivocal evi- northwestern side of the Innuitian Ice Sheet ablated earlier dence of a small transgression at 5 ka has been presented and more rapidly than the southeastern side. An asymmetric (e.g., Blake 1975; Dyke et al. 1991). This may imply that ablation pattern can be reasonably explained in two ways. It the Holocene transgressions which are well documented could be due to greater vulnerability of the northwestern elsewhere in glaciated eastern Canada, such as along the St. side to eustatic sea-level rise, because most of that part of Lawrence estuary (Dionne 1988; Dionne and Occhietti the ice sheet bed was below sea level. Alternatively or addi- 1996), have noneustatic origins. tionally, it could be due to higher snow accumulation on the The response times of the curves are similar at the heavily southeastern side. Higher southeastern accumulation would loaded sites, with half-lives of about 2 ka, but evidently de- signify Baffin Bay or North Atlantic moisture penetrating to crease to about 1 ka near the ice margin. This pattern appar- this area under regional (but not global) glacial maximal ently has not been reported previously and runs counter to conditions. the best earlier analysis (Andrews 1970). It needs to be The emergence of the point 200 km along profile A–B tested with further studies and its geophysical implications (Fig. 7), the late Holocene uplift centre on Grinnell Penin- should be addressed beyond the speculations offered above. sula, proceeded at 5.4 m per century at 8.5 ka, 2.2 m per The regional pattern of delevelling involves two major el- century at 7.5 ka, 1.8 m per century at 6.5 ka, 1.25 m per ements: a consistent northwestward rise of paleoshorelines century at 5.5 ka, 0.75 m per century at 4.5 ka, 0.6 m per and a strong embayment of isobases over Lancaster Sound. century at 3 ka, 0.45 m per century at 1.5 ka, and 0.35 m per The former is congruent with the Innuitian ice load inferred century at 0.5 ka BP. The current emergence rate is 0.3 m by Blake (1970). The latter separates the Laurentide and per century. Projecting this declining rate forward linearly, Innuitian uplifts. The straight isobases across Jones Sound, uplift at the centre will continue for another 4 ka and an- in contrast, signify a greater load there than is otherwise evi- other 6.25 m of emergence will occur. This is a slightly min- dent from the glacial geology. The centre (or axis) of imal estimate of residual uplift, because, in reality, the rates Innuitian uplift migrated at least 250 km southeastward be- will decrease asymptotically. The emergence rates derived tween 10 and 6 ka BP, presumably reflecting earlier ablation from the shoreline profiles are probably more reliable than of the polar flank of the ice sheet. Residual rebound at the those which might be derived from any of the RSL curves. uplift centre on Grinnell Peninsula is not much more than 6.25 m, which will be mostly accomplished in the next 4 ka.
Early models of glaciation of the Queen Elizabeth Islands were based to a large degree on regional uplift patterns. Field surveys in 1993, 1994, and 1997 were supported by However, the reconstructed uplift patterns have remained the Polar Continental Shelf Project of Natural Resources somewhat fluid as RSL databases have evolved and much Canada. C. Miller and M. Dance assisted in the field in 1993 work remains to accurately characterize the entire uplift. Re- and 1994, respectively. J. England and C. O’Cofaigh (Uni- cently, uplift patterns in the Queen Elizabeth Islands have versity of Alberta) joined me in a two-day survey of marine- been regarded as insufficient evidence of any particular ice limit deltas in 1997. Analytical support was provided by the load configuration, because nonunique geophysical model radiocarbon laboratories of the Geological Survey of Canada solutions of the RSL history are possible. For this reason, (GSC) (R. McNeely), Saskatchewan Research Council (J. the Devon Island project attempted to reconstruct LGM ice Zimmer), and University of Toronto (R. Beukens). R.B. Tay- extent and configuration from primary glacial geological ev- lor (GSC Atlantic) contributed unpublished radiocarbon idence. That evidence supports Blake’s (1970) Innuitian Ice dates from Radstock Bay and comments on an early draft. I Sheet hypothesis (Dyke 1998). Similar support for this hy- also appreciate informal reviews by Tom James (GSC Pa- pothesis arises from reinterpretations of the glacial history of cific), D.A. Hodgson and W. Blake, Jr. (GSC Ottawa), and J. Nares Strait (England 1998) and Nansen Sound (Bednarski Bednarski (GSC Calgary) along with the helpful formal re- 1998). views by J. Shaw (GSC Atlantic) and J. England. The Holocene RSL history of Devon Island encapsulates a complete radius of the Innuitian Ice Sheet, and hence of the Innuitian uplift. This history is constrained by 154 new ra- Allard, M., and Tremblay, G. 1983. La dynamique littorale des îles diocarbon dates, many of these on driftwood and whale Manitounuk durant l’Holocène. Zeitschrift fur Geomorphologie, bones from raised beaches. Twelve of the 14 RSL curves Supplement-Band, 47: 61–95. now available are well described by simple exponential Andrews, J.T. 1970. A geomorphological study of postglacial uplift regression fits. The eastern part of the island has a more with particular reference to Arctic Canada. Institute of British complex curve incorporating early Holocene emergence, a Geographers, Special Publication 2. middle Holocene lowstand, the best estimate for which is –15 m Andrews, J.T., and Peltier, W.R. 1989. Quaternary geodynamics in at Croker Bay, and continuing late Holocene submergence. Canada. In Quaternary geology of Canada and Greenland. The zero isobase (roughly the proximal side of the crustal Edited by R.J. Fulton. Geological Survey of Canada, Geology of forebulge in the late Holocene) has migrated about 220 km Canada, No. 1. westward since 9 ka BP, thus accounting for the eastern sub- Barr, W. 1971. Postglacial isostatic movements in northeastern mergence. The lack of any detectable century- to millennial- Devon Island: a reappraisal. Arctic, 24: 249–268.
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Bednarski, J.M. 1998. Quaternary history of Axel Heiberg Island, adjustment approach: Discussion. Canadian Journal of Earth bordering Nansen Sound, Northwest Territories, emphasizing Sciences, 28: 1689–1695. the last glacial maximum. Canadian Journal of Earth Sciences, Fairbanks, R.G. 1989. A 17 000-year glacio-eustatic sea level re- 35: 520–533. cord: influence of glacial melting rates on the Younger Dryas Blake, W., Jr. 1970. Studies of glacial history in Arctic Canada I: event and deep-ocean circulation. Nature (London), 342: 637– pumice, radiocarbon dates, and differential postglacial uplift in 642. the eastern Queen Elizabeth Islands. Canadian Journal of Earth Fisher, D.A. 1979. Comparison of 105 years of oxygen isotope and Sciences, 7: 634–664. insoluble impurity profiles from the Devon Island and Camp Blake, W., Jr. 1975. Radiocarbon age determinations and Century ice cores. Quaternary Research, 11: 299–305. postglacial emergence at Cape Storm, southern Ellesmere Is- Glushankova, N.I., Parunin, O.B., Timashkova, T.A., Khait, V.Z., land. Geografiska Annaler, Series A, 57: 1–71. and Shlukov, A.I. 1980. Moscow MV Lomonosov State Univer- Blake, W., Jr. 1987. Geological Survey of Canada radiocarbon sity radiocarbon dates I. Radiocarbon, 22: 82–90. dates XXVI. Geological Survey of Canada, Paper 86-7. Grosswald, M.G. 1983. Ice sheets on the continental shelves. In Blake, W., Jr. 1988. Geological Survey of Canada radiocarbon Results of researches on the international geophysical projects. dates XXVII. Geological Survey of Canada, Paper 87-7. Nauka, Moscow. (In Russian.) Blake, W., Jr. 1993. Holocene emergence along the Ellesmere Is- Helmer, J.W. 1991. The paleo-eskimo prehistory of the north land coasts of northernmost Baffin Bay. Norsk Geologisk Devon lowlands. Arctic, 44: 301–317. Tidsskrift, 73: 147–160. Hooper, J.G. 1996. 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Marine and terrestrial Island, Arctic Canada: support for an Innuitian Ice Sheet. Qua- mammals in high arctic Paleoeskimo economy. ternary Science Reviews. In press. Archaeozoologia, III/1, 2: 143–159. Dyke, A.S., and Prest, V.K. 1987. Late Wisconsinan and Holocene McCuaig, S.J. 1994. Glacial chronology of the south Bylot and history of the Laurentide Ice Sheet. Géographie physique et Salmon River lowlands, N.W.T., using erratic dispersal patterns, Quaternaire, 41: 237–263. cosmogenic dating, radiocarbon dating and lichenometry. M.Sc. Dyke, A.S., Morris, T.F., and Green, D.E.C. 1991. Postglacial tec- thesis, Carleton University, Ottawa. tonic and sea level history of the central Canadian Arctic. Geo- McGhee, R. 1976. Paleoeskimo occupations of central and high logical Survey of Canada, Bulletin 397. arctic Canada. In Eastern arctic prehistory: paleoeskimo prob- Dyke, A.S., McNeely, R.N., and Hooper, J. 1996. Marine reservoir lems. Edited by M.S. Maxwell. Society for American Archaeol- corrections for bowhead whale radiocarbon age determinations. ogy, Memoir 31, pp. 15–39. Canadian Journal of Earth Sciences, 33: 1628–1637. McNeely, R. 1989. Geological Survey of Canada radiocarbon dates England, J. 1976a. Late Quaternary glaciation of the eastern Queen XXVIII. Geological Survey of Canada, Paper 88-7. Elizabeth Islands, northwest Territories, Canada: alternative Müller, F., and Barr, W. 1966. Postglacial isostatic movement in models. Quaternary Research, 6: 185–202. northeastern Devon Island, Canadian Arctic Archipelago. Arc- England, J. 1976b. Postglacial isobases and uplift curves from the tic, 19: 263–269. Canadian and Greenland High Arctic. Arctic and Alpine Re- Park, R.W. 1989. Porden Point: an intrasite approach to settlement search, 8: 61–78. system analysis. Ph.D. thesis, University of Alberta, Edmonton. England, J. 1987. Glaciation and the evolution of the Canadian Stuiver, M., and Reimer, P.J. 1993. Extended 14C data base and re- high arctic landscape. Geology, 15: 419–424. vised CALIB 3.0 radiocarbon age calibration program. Radio- England, J. 1997. Unusual rates and patterns of Holocene emer- carbon, 35: 215–230. gence, Ellesmere Island, Arctic Canada. Journal of the Geologi- Tushingham, A.M. 1991. On the extent and thickness of the cal Society, London, 154: 781–792. Innuitian Ice Sheet: a postglacial-adjustment approach. Cana- England, J. 1998. Coalescent Greenland and Innuitian ice during dian Journal of Earth Sciences, 28: 231–239. the last glacial maximum: revising the Quaternary of the Cana- Tushingham, A.M., and Peltier, W.R. 1991. Ice-3G: a new global dian High Arctic. Quaternary Science Reviews. In press. model of late Pleistocene deglaciation based on geophysical pre- England, J., Sharp, M., Lemmen, D.S., and Bednarski, J. 1991. On dictions of post-glacial relative sea level change. Journal of the extent and thickness of the Innuitian Ice Sheet: a postglacial- Geophysical Research, B, 96: 4497–4523.
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Walcott, R.I. 1970. Isostatic response to loading of the crust in Washburn, A.L., and Stuiver, M. 1985. Radiocarbon dates from Canada. Canadian Journal of Earth Sciences, 7: 716–726. Cornwallis Island area, Arctic Canada—an interim report. Cana- Walcott, R.I. 1972. Late Quaternary vertical movements in eastern dian Journal of Earth Sciences, 22: 630–636. North America: quantitative evidence of glacio-isostatic re- Wickenden, R.T.D. 1947. Pleistocene glacial deposits. In Geology bound. Reviews of Geophysics and Space Physics, 10: 849–884. and economic minerals of Canada. 3rd ed. Geological Survey of Washburn, A.L. 1947. Reconnaissance geology of portions of Vic- Canada, Ottawa, pp. 325–346. toria Island and adjacent regions. Geological Society of Amer- ica, Memoir 22.
Table A1. Radiocarbon dates pertaining to relative sea levels (RSL) from the study area. Sites are listed alphabetically within each region. RSL (m) Lab. No. Material dated and context Min. Max. Age (ka, ±SE) Lat. N Long. W δ13C (‰) Grinnell Peninsula Barrow Harbour (no curve) GSC-1765 Mya truncata, delta 110 116 8.5±0.15 76°35′ 95°31.5′ GSC-1810 Marine algae; age anomalous 51 — 10.2±0.14 76°35.2′ 95°33′ GSC-1771 Salix sp. detritus, delta 35 — 6.94±0.18 76°35′ 95°33′ Bere Bay (Fig. 4B) GSC-5662 M. truncata, ML delta 99 — 8.63±0.09 76°51′28′′ 94°13′56′′ S-3537 Balaena mysticetus 10.5 — 2.58±0.20 76°57′27′′ 94°33′09′′ –16 GSC-5788* Larix sp. driftwood; moved 12 — 7.02±0.08 76°57′53′′ 94°34′52′′ GSC-5800 Pinus sp. driftwood 6 — 1.42±0.05 76°55′11′′ 93°53′52′′ GSC-5793 Hiatella arctica, delta 44 — 6.45±0.07 76°51′20′′ 94°06′30′′ GSC-5794 Astarte borealis, delta 29 — 5.14±0.06 76°52′07′′ 94°09′12′′ GSC-5805 Picea sp. driftwood 8 — 2.09±0.06 76°58′21′′ 94°41′15′′ GSC-5829 A. borealis, delta 5 — 2.25±0.06 76°53′58′′ 94°19′31′′ GSC-5830 A. borealis, delta 5 — 2.76±0.07 76°53′58′′ 94°19′31′′ GSC-5832 A. borealis, delta 9 — 2.94±0.07 76°54′02′′ 94°21′35′′ GSC-6126 Serripes groenlandicus, delta 5 — 1.55±0.06 76°53′58′′ 94°19′31′′ GSC-6132 Plant detritus, delta 5 — 2.18±0.07 76°53′58′′ 94°19′31′′ GSC-6070 Salix arctica detritus, delta 25.5 — 4.95±0.06 76°52′12′′ 94°08′29′′ GSC-6080 S. arctica detritus, delta 25.5 — 4.23±0.08 76°52′24′′ 94°08′42′′ GSC-6096* Plant detritus, delta; redeposited 12 ? 5.28±0.08 76°52′38′′ 94°09′01′′ GSC-5732 M. truncata, marine-limit (ML) delta 86 114 8.84±0.08 76°57′35′′ 94°52′28′′ foreslope Lyall River (Fig. 4A) GSC-2188 Picea sp. driftwood 15 — 3.68±0.07 76°57.8′ 96°43′ S-3566 B. mysticetus 12 — 2.82±0.17 77°03′03′′ 95°24′06′′ –15.9 S-3567 B. mysticetus 3.5 — 1.24±0.17 77°03′24′′ 95°32′52′′ –15.5 TO-5961 Odobenus rosmarus 25 — 4.75±0.06 77° 03′21′′ 95° 30′35′′ GSC-5917 M. truncata, delta 25.5 — 5.02±0.08 77°01′21′′ 95°20′26′′ GSC-5853 H. arctica, surface 126 131 8.68±0.11 77°00′45′′ 95°23′00′′ GSC-5859 H. arctica, ML delta 117 117 8.76±0.10 76°57′37′′ 95°15′16′′ GSC-1128 M. truncata, surface 89 — 8.43±0.14 76°57.5′ 95°22′ Port Refuge (Fig. 4C) GSC-1952 Larix sp. driftwood 16.5 — 3.07±0.07 76°17′ 94°49′ GSC-1931* Charcoal, archaeological ? 24 4.12±0.12 76°17′ 94°48′ GSC-1940* Charcoal, archaeological ? 22 4.36±0.09 76°17′ 94°48′ GSC-1949* Charcoal, archaeological ? 22 3.48±0.14 76°17′ 94°48′ GSC-5951 Picea sp. driftwood 7 — 1.45±0.07 76°15′ 94°57′41′′ GSC-5954 Larix sp. driftwood 24.5 — 3.69±0.09 76°14′49′′ 94°59′26′′ MGU-333 Marine shells, surface 62 ? 7.59±0.10 76°23′ 95°37′ MGU-332 Marine shells, surface 45 ? 6.336±0.16 76°23′ 95°37′ MGU-330* Marine shells, surface 84 ? 11.28±0.16 76°15′ 95°16′ MGU-331 Marine shells, surface 98 ? 8.57±0.12 76°23′ 95°31′ GSC-5901* M. truncata, section 40 ? 7.81±0.08 76°23′36′′ 95°17′57′′ GSC-5920 M. truncata, delta 26 — 4.58±0.07 76°18′33′′ 94°39′36′′
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Table A1 (continued). RSL (m) Lab. No. Material dated and context Min. Max. Age (ka, ±SE) Lat. N Long. W δ13C (‰) GSC-1766* Larix sp. driftwood; moved 21 — 2.96±0.13 76°14.5′ 95°19′ GSC-5850 M. truncata, ML delta 91 91 8.2±0.09 76°22′33′′ 94°55′22′′ S-3564 B. mysticetus 16.5 — 3.18±0.15 76°16′48′′ 94°49′20′′ –16.2 S-1660* Seal bone, archaeological ? 24 4.45±0.06 76°19′ 94°38′ S-1661* Seal bone, archaeological ? 24 3.43±0.06 76°19′ 94°38′ S-1662* Seal bone, archaeological ? 24 3.79±0.06 76°19′ 94°38′ S-1689* Seal bone, archaeological ? 24 2.07±0.05 76°19′ 94°38′ Prince Alfred Bay (Fig. 4D) GSC-5816 Picea sp. driftwood 2.5 — 0.69±0.05 76°21′32′′ 93°04′46′′ S-3536 B. mysticetus 3 — 0.93±0.15 76°17′22′′ 93°47′36′′ –15.5 S-3559 B. mysticetus 3 — 1.29±0.14 76°19′54′′ 93°27′09′′ –15.2 S-1422* Sphagnum, archaeological ? 4 1.00±0.11 76°15′ 92°40′ S-1423* B. mysticetus, archaeological ? 4 1.34±0.07 76°15′ 92°40′ S-1424* Seal bone, archaeological ? 4 1.31±0.07 76°15′ 92°40′ S-1420* Twigs, moss, leaves, archaeological ? 4 0.55±0.07 76°15′ 92°40′ S-1421* Twigs, moss, leaves, archaeological ? 4 1.38±0.09 76°15′ 92°40′ S-3535 B. mysticetus 4.25 — 1.06±0.14 76°17′04′′ 94°17′54′′ –14.7 GSC-5814 Pinus sp. driftwood 5.5 — 1.56±0.06 76°15′57′′ 93°43′02′′ GSC-5808 Picea sp. driftwood 7 — 1.92±0.06 76°17′31′′ 93°47′38′′ S-3534 B. mysticetus 8 — 1.93±0.17 76°19′20′′ 93°43′54′′ –13.8 GSC-5846 Picea sp. driftwood 8 — 1.85±0.06 76°17′31′′ 93°47′38′′ GSC-5812 Pinus sp. driftwood 9 — 2.06±0.06 76°22′10′′ 93°16′09′′ GSC-5811 Picea sp. driftwood 11.75 — 2.25±0.06 76°22′23′′ 93°12′41′′ S-3533 B. mysticetus 13 — 2.66±0.15 76°19′13′′ 93°45′23′′ –14.9 GSC-5847 Larix sp. driftwood 13.25 — 2.28±0.06 76°22′22′′ 93°13′55′′ S-3556 B. mysticetus 14.25 — 3.08±0.15 76°21′51′′ 93°04′10′′ –14.5 GSC-5817* Larix sp. driftwood; moved ? ? 1.94±0.07 76°24′15′′ 93°35′22′′ GSC-5786 Larix sp. driftwood 17.5 — 3.74±0.06 76°21′30′′ 93°23′38′′ S-3532 B. mysticetus 18 — 3.8±0.15 76°19′35′′ 93°43′10′′ –15.2 GSC-5782 Larix sp. driftwood 20 — 3.8±0.08 76°22′35′′ 93°15′55′′ TO-5063* O. rosmarus; crawler? ? ? 3.48±0.06 76° 17′34′′ 93° 48′49′′ GSC-5778 Larix sp. driftwood 25 — 4.45±0.06 76°18′12′′ 93°48′49′′ GSC-1699* Larix sp. driftwood; moved ? ? 4.41±0.15 76°15.5′ 93°38′ GSC-6165 M. truncata, delta 29 ? 5.5±0.07 76° 22′42′′ 93° 39′56′′ GSC-5698 A. borealis, ML delta 80 80 8.31±0.11 76°27′18′′ 93°41′49′′ GSC-5653 M. truncata, glaciomarine sediment in front 86 95 8.55±0.07 76°19′59′′ 93°53′49′′ of ML delta Wilmer Bay (no curve) GSC-5739 H. arctica, glaciomarine sediment in front 90 101 8.61±0.08 76°45′55′′ 93°32′42′′ of ML terrace GSC-5824 A. borealis, delta 55 — 7.38±0.08 76°46′09′′ 93°27′43′′ GSC-5827 A. borealis, delta 9 — 3.76±0.10 76°49′02′′ 93°27′24′′ GSC-5818 Picea sp. driftwood 4 — 1.12±0.10 76°49′17′′ 93°28′12′′ Hell Gate region North Kent Island (no curve) GSC-5881 M. truncata, surface 80 ? 7.58±0.10 76°46′01′′ 90°29′18′′ GSC-907 M. truncata, H. arctica, surface; blended — ? 9.78±0.20 76°49′ 90°13′ age? Southwest Ellesmere Island (no curve) GSC-858 H. arctica, surface near ML 120 — 8.72±0.11 76° 28′ 88° 18′ GSC-5870 H. arctica, surface 51 ? 7.19±0.07 76° 57′06′′ 88° 48′06′ GSC-5899 M. truncata, surface 98 ? 7.81±0.21 76° 56′32′′ 88° 58′21′′ Triton Bay (Fig. 4E) GSC-5856 H. arctica, glaciomarine sediment near ML 100 110 8.44±0.09 76°32′29′′ 92°24′33′′ S-3568 B. mysticetus 7 — 2.11±0.20 76°36′56′′ 92°32′11′′ –15.6 GSC-5952 Picea sp. driftwood 7.25 — 1.76±0.07 76°35′56′′ 92°19′31′′
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Table A1 (continued). RSL (m) Lab. No. Material dated and context Min. Max. Age (ka, ±SE) Lat. N Long. W δ13C (‰) GSC-5939 M. truncata, surface 64 — 8.07±0.09 76°32′38′′ 92°28′13′′ GSC-5963 A. borealis, beach 23.25 — 4.62±0.08 76°36′27′′ 92°08′07′′ GSC-5970 A. borealis, mud below beach 26.5 — 5.91±0.09 76°33′00′′ 92°29′03′′ GSC-5885 M. truncata, delta 35.5 — 6.23±0.08 76°29′45′′ 91°38′44′′ GSC-5976 A. borealis, mud below beach 6.25 — 2.85±0.06 76°37′06′′ 92°07′24′′ GSC-5900 Salix sp. and Dryas sp. detritus, delta 35.5 — 6.16±0.08 76°29′45′′ 91°38′44′′ TO-4806 Salix sp. and Dryas sp. detritus, delta 35.5 — 5.92±0.06 76°29′45′′ 91°38′44′′ Cardigan Strait (no curve) GSC-2178 Picea sp. charcoal, archaeological ? 19 3.58±0.15 76°30′ 90°34′ Wellington Channel Baillie-Hamilton Island (no curve) GSC-5874 M. truncata, surface near ML 103 110 8.62±0.08 75°46′30′′ 94°21′00′′ Dragleybeck Inlet (no curve) GSC-6200 H. arctica, thick glaciomarine silt in front 50 83 8.17±0.09 75°36.06′ 91°47.17′ of ML delta Dundas Island (no curve) GSC-1914 Picea sp. driftwood 26.5 — 4.38±0.08 76°07′ 94°54′ Griffin Inlet (no curve) GSC-6203 H. arctica and M. truncata, mud in front of 75 90.5 8.73±0.08 75°11.29′ 92°00.83′ ML delta Lovell Point (Fig. 4I) GSC-5876 Larix sp. driftwood 21 — 5.85±0.07 74°55′42′′ 91°59′23′′ GSC-5873 Larix sp. driftwood 24 — 5.88±0.09 74°54′51′′ 92°00′33′′ GSC-5861 Larix sp. driftwood 41 — 7.78±0.08 74°52′34′′ 92°01′03′′ GSC-5902 Picea sp. driftwood 9.5 — 2.45±0.06 74°50′37′′ 92°02′58′′ GSC-5893 Picea sp. driftwood 18 — 5.51±0.07 74°55′37′′ 92°00′00′′ GSC-5894 Picea sp. driftwood 14 — 4.55±0.07 74°54′36′′ 92°01′21′′ GSC-5904 Larix sp. driftwood 3 — 1.41±0.05 74°57′30′′ 92°01′54′′ GSC-5910* Picea sp. driftwood 19 — 3.75±0.10 74°54′42′′ 92°01′04′′ GSC-5919 Picea sp. driftwood 16 — 4.64±0.07 74°53′42′′ 92°00′55′′ GSC-5926 Picea sp. driftwood 5.5 — 1.84±0.07 74°50′29′′ 92°03′11′′ S-3597 B. mysticetus 76.5 — 9.12±0.20 74°57′38′′ 91°59′55′′ –16 S-3598 B. mysticetus 40 — 7.71±0.18 74°58′30′′ 92°05′14′′ –16.2 S-3600 B. mysticetus 64.5 — 8.72±0.19 74°59′49′′ 92°08′19′′ –16.4 S-3599 B. mysticetus 35 — 7.63±0.16 74°51′13′′ 92°01′57′′ –16.1 S-3601 B. mysticetus 57 — 8.62±0.17 74°52′10′′ 92°00′07′′ –17.4 GSC-5866* H. arctica, surface of ML delta foreslope 69 86 7.95±0.10 74°55′36′′ 91°50′40′′ TO-5507* H. arctica, surface of ML delta foreslope 69 86 8.34±0.07 74°55′36′′ 91°50′40′′ GSC-5867* M. truncata, surface 83 106.5 8.22±0.09 74°51′32′′ 91°57′11′′ TO-5509* M. truncata, surface 83 106.5 7.41±0.07 74°51′32′′ 91°57′11′′ GSC-5975* M. truncata, delta 65 86 7.98±0.08 74°55′53′′ 91°51′43′′ TO-5508* H. arctica, same sample as GSC-5975 65 86 8.01±0.07 74°55′53′′ 91°51′43′′ GSC-5863* M. truncata, surface in front of ML fan 91 91 8.16±0.09 74°58′07′′ 92°01′55′′ TO-4926* M. truncata, surface in front of ML fan 91 91 7.56±0.07 74°58′07′′ 92°01′55′′ Macormick Bay (no curve) GSC-6198 H. arctica, stony mud in front of ML delta 90 102 8.9±0.10 75°23.04′ 92°14.19′ Owen Point (Fig. 4F) S-3531 B. mysticetus 3 — 0.54±0.13 76°01′05′′ 92°40′13′′ –15.2 S-3530 B. mysticetus 6.5 — 1.81±0.18 76°08′03′′ 92°40′02′′ –15.2 GSC-5815 Picea sp. driftwood 9.25 — 1.4±0.05 76°07′04′′ 92°37′40′′ S-3529 B. mysticetus 9.5 — 2.02±0.14 75°55′42′′ 92°20′45′′ –15.3 GSC-5810 Picea sp. driftwood 14 — 3.35±0.16 76°08′37′′ 92°41′15′′ S-3528 B. mysticetus 15 — 3.36±0.15 76°08′06′′ 92°39′31′′ –15.5 GSC-5771 Larix sp. driftwood 16 — 3.75±0.08 76°04′01′′ 92°37′16′′ S-3545 B. mysticetus 19 — 3.975±0.26 76°09′47′′ 92°45′37′′ –15.9
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Table A1 (continued). RSL (m) Lab. No. Material dated and context Min. Max. Age (ka, ±SE) Lat. N Long. W δ13C (‰) S-3555 B. mysticetus 23 — 4.46±0.15 76°01′39′′ 92°33′29′′ –13.9 S-3521 B. mysticetus 26 — 4.76±0.26 76°00′24′′ 92°29′06′′ –16.1 S-3544* O. rosmarus; crawler ? — 1.49±0.17 75°57′21′′ 92°08′23′′ –13.8 GSC-5756 S. groenlandicus, delta 38.5 — 7.2±0.08 76°01′27′′ 92°24′45′′ GSC-5740 S. groenlandicus, delta 53 — 7.91±0.07 76°02′23′′ 92°22′51′′ GSC-5813 M. truncata, delta 62 — 7.97±0.08 76°03′31′′ 92°19′53′′ GSC-5733 M. truncata, H. arctica, surface near ML 71 84 8.24±0.11 76°04′21′′ 92°21′56′′ Providence Mountain (Fig. 4H) GSC-5659 H. arctica, surface near ML 66 78 8.23±0.09 75°37′04′′ 91°33′29′′ GSC-5768 Larix sp. driftwood 12.25 — 3.05±0.05 75°39′48′′ 91°58′48′′ GSC-5806 Picea sp. driftwood 2 — 1.02±0.05 75°42′51′′ 92°05′59′′ GSC-5825* Peat ? 36 3.38±0.06 75°40′23′′ 91°52′45′′ S-3522 B. mysticetus 9 — 2.58±0.16 75°40′19′′ 92°00′41′′ –15.1 Sophia Cove (no curve) GSC-6201 H. arctica, stony mud in front of ML delta 40 66.5 8.61±0.09 75°07.98′ 91°46.35′ Lancaster Sound Croker Bay (Figs. 4N, 4O) GSC-5918* Picea sp. driftwood; moved — ? 1.24±0.05 74° 34′26′′ 83° 34′42′′ S-3579 B. mysticetus 10.25 — 8.47±0.19 74°32′54′′ 83°37′09′′ –16.8 S-3580 B. mysticetus 32.5 — 9.54±0.20 74°34′27′′ 83°39′27′′ –16.1 S-3581 B. mysticetus 14.25 — 9.06±0.21 74°33′09′′ 83°38′22′′ –16.9 S-3582 B. mysticetus 11.75 — 8.75±0.20 74°33′04′′ 83°38′20′′ –16.4 S-3583 B. mysticetus 6.25 — 8.42±0.19 74°32′56′′ 83°36′02′′ –17.4 S-3584 B. mysticetus 11.75 — 8.73±0.19 74°33′24′′ 83°40′15′′ –17.1 S-3585 B. mysticetus 16 — 9.17±0.20 74°33′26′′ 83°41′38′′ –17.4 S-3586 B. mysticetus 3.5 — 8.39±0.20 74°33′07′′ 83°43′15′′ –17 S-3587 B. mysticetus 8.25 — 8.57±0.20 74°33′17′′ 83°51′36′′ –16.6 S-3588 B. mysticetus 5.5 — 8.49±0.20 74°36′49′′ 83°28′16′′ –16.2 S-3589 B. mysticetus 9 — 8.82±0.20 74°33′27′′ 83°43′32′′ –17.6 S-3590 B. mysticetus 20.25 — 9.15±0.19 74°33′56′′ 83°42′35′′ –16.8 S-3591 B. mysticetus 29 — 9.74±0.20 74°34′19′′ 83°38′54′′ –15.8 S-3592 B. mysticetus 21 — 9.45±0.19 74°34′29′′ 83°37′43′′ –16.9 S-3593 B. mysticetus 16 — 9.11±0.19 74°33′56′′ 83°36′30′′ –16.5 S-3594 B. mysticetus 17.5 — 8.97±0.19 74°35′35′′ 83°33′10′′ –16.6 S-3595 B. mysticetus; best limiting age for ML 13 37.5 9.92±0.18 74°35′39′′ 83°31′45′′ –16.6 S-3596 B. mysticetus 11.75 — 8.77±0.17 74°41′51′′ 83°22′45′′ –17.2 S-3612 B. mysticetus 19 — 9.2±0.17 74°33′41′′ 83°39′43′′ –16.4 Maxwell Bay (no curve) GSC-6187 H. arctica, stony mud at toe of ML delta 56 56 8.76±0.10 74°50.64′ 88°25.27′ GSC-6195 M. truncata, stony clay below delta terrace 37 30 8.38±0.09 74°45.24′ 88°25.29 at 30 m Radstock Bay (outer) (Fig. 4J) GSC-1456 Driftwood 4.7 — 2.03±0.13 74°40′ 91°25′ GSC-1402 Tsuga sp. driftwood 12.2 — 4.17±0.13 74°42′ 91°13′ GSC-1467 Picea sp. or Larix sp. driftwood 16.5 — 5.17±0.14 74°40′ 91°25′ GSC-5548 H. arctica, section 33 ? 8.6±0.09 74°37.65′ 91°16.65′ GSC-5562 H. arctica, section 56 ? 8.55±0.09 74°39.46′ 91°18.75′ GSC-5940 H. arctica, surface at ML 115 115 9.47±0.09 74°39.3′ 91°17.9′ GSC-1479* Peat ? 48.5 8.26±0.16 74°35′ 91°23′ GSC-1502 Balanus balanus, surface 105 — 9.26±0.15 74°40′ 91°25′ Radstock Bay (inner) (no curve) GSC-6189 H. arctica, stony mud on foreslope of ML 40 65 8.04±0.08 74°54.18′ 90°34.74′ delta
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Table A1 (continued).
RSL (m) Lab. No. Material dated and context Min. Max. Age (ka, ±SE) Lat. N Long. W δ13C (‰) Powell Inlet (no curve) GSC-6191 H. arctica, stony mud on foreslope of ML 41.5 41.5 8.86±0.08 74°41.42′ 85°34.10′ delta GSC-6202 H. arctica, foreset gravel of delta 21 — 8.78±0.10 74°51.30′ 85°33.50′ Stratton Inlet (no curve) GSC-6185 H. arctica, foreset gravel, ML delta 55 55 8.82±0.10 74°37.04′ 86°47.08′ Jones Sound Cape Hardy (Fig. 4M) S-435* Marine shells 11 ? 8.1±0.15 75°47′ 83°35′ S-436* Marine algae 4.2 ? 9.3±0.18 75°47′ 83°35′ S-437* Marine shells 2.9 ? 8.5±0.15 75°47′ 83°35′ S-3569 B. mysticetus 26 — 8.04±0.20 75°47′24′′ 83°53′30′′ –17.4 S-3570 B. mysticetus 26 — 8.11±0.19 75°47′22′′ 83°53′27′′ –17 S-3571 B. mysticetus 2.25 — 3.55±0.15 75°46′03′′ 84°01′33′′ –16 S-3572 B. mysticetus 64.5 — 9.42±0.20 75°46′24′′ 83°51′17′′ –16.7 S-3573 B. mysticetus 57 — 9.14±0.20 75°46′54′′ 83°45′15′′ –16.5 S-3574 B. mysticetus 4.5 — 4.9±0.17 75°47′28′′ 83°40′45′′ –16.1 S-3575 B. mysticetus 43 — 9.05±0.18 75°46′11′′ 83°54′19′′ –17 S-3576 B. mysticetus 46 — 8.95±0.18 75°46′22′′ 83°52′59′′ –16.5 S-3577 B. mysticetus 7 — 4.74±0.15 75°46′38′′ 83°59′53′′ –16 S-3578 B. mysticetus 31.5 — 8.17±0.17 75°46′ 83°56′42′′ –17.6 S-3611 B. mysticetus 29 — 8.21±0.17 75°45′56′′ 83°57′43′′ –16.5 TO-5962 O. rosmarus 44 — 8.85±0.08 75°45′53′′ 83°55′26′′ Colin Archer Peninsula (Fig. 4G) GSC-866 H. arctica, Mya sp., surface near ML 114 — 9.26±0.10 76°17′ 89°22′ GSC-874 H. arctica, Mya sp., surface near ML 114 — 8.95±0.08 76°28.5′ 90°45′ GSC-1606 Picea sp. driftwood 24 — 4.5±0.13 75°58.5′ 89°58′ GSC-1072 Picea sp. driftwood 26.5 — 5.25±0.13 75°58.5′ 89°58′ GSC-1704 Picea sp. driftwood 25 — 5.02±0.14 76°13.5′ 89°19′ GSC-2996 Picea sp. driftwood 19 — 3.66±0.06 76°10′40′′ 91°22′30′′ GSC-3008 Picea sp. driftwood 35 — 5.96±0.07 76°10′40′′ 91°22′30′′ GSC-3006* M. truncata, glaciomarine sediment 48 ? 8.44±0.08 76°09′30′′ 91°31′ Fiord south of Nookap Island (no curve) GSC-6184 H. arctica, foreset sand of ML delta 69.5 69.5 9.09±0.11 75°25.89′ 87°36.01′ Firkin Point (Fig. 4L) S-3525 B. mysticetus 30 — 8.07±0.18 75°32′29′′ 85°46′05′′ –16.5 S-3524 B. mysticetus 32 — 8.15±0.19 75°33′39′′ 85°36′46′′ –16.1 S-3523 B. mysticetus 32.5 — 7.92±0.18 75°33′30′′ 85°40′14′′ –16.5 S-3526 B. mysticetus 8.5 — 5.05±0.16 75°34′08′′ 85°40′07′′ –15.2 S-3538 B. mysticetus 25 — 7.75±0.18 75°33′46′′ 85°39′29′′ –16.6 S-3539 B. mysticetus 12.5 — 6.06±0.16 75°33′12′′ 85°44′28′′ –16 S-3540 B. mysticetus 12.5 — 5.78±0.16 75°33′11′′ 85°44′41′′ –16.9 S-3541 B. mysticetus 11.25 — 5.13±0.26 75°34′13′′ 85°38′16′′ –16.6 S-3542 B. mysticetus 5.75 — 4.05±0.15 75°34′24′′ 85°39′39′′ –16.2 S-3543 B. mysticetus 4.5 — 3.64±0.14 75°35′12′′ 85°36′31′′ –19.9 S-3558 B. mysticetus 32 — 7.94±0.19 75°33′37′′ 85°37′06′′ –16.7 S-3557 B. mysticetus 8.5 — 4.96±0.16 75°33′56′′ 85°40′59′′ –15.6 GSC-5737 H. arctica, surface 26 43 7.93±0.09 75°33′25′′ 85°21′16′′ S-3643 O. rosmarus 14 — 6.79±0.10 75°34′02′′ 85°39′25′′ –12.9 S-3527 O. rosmarus 19 — 6.87±0.18 75°32′33′′ 85°47′15′′ –13.6 Sandhook Bay (no curve) GSC-6192 M. truncata, foreset sand of delta at 86 m; 86 — 8.85±0.10 75°47.45′ 90°04.33′ ML delta nearby at 94.5 m
© 1998 NRC Canada
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904 Can. J. Earth Sci. Vol. 35, 1998
Table A1 (concluded). RSL (m) Lab. No. Material dated and context Min. Max. Age (ka, ±SE) Lat. N Long. W δ13C (‰) Thomas Lee Inlet (Fig. 4K) GSC-1661 M. truncata, ML delta 73 76 8.49±0.10 75°32.5′ 89°59.5′ GSC-5667 M. truncata, ML delta 79 79 8.83±0.10 75°20′34′′ 88°38′02′′ GSC-5791 Picea sp. driftwood 20 — 6.5±0.08 75°28′ 88°45′53′′ GSC-5795 Picea sp. driftwood 4 — 3.06±0.05 75°27′22′′ 88°45′54′′ GSC-5682 M. truncata, H. arctica, surface 76 102 8.72±0.10 75°27′15′′ 88°44′06′′ Viks Fiord (no curve) GSC-6197 H. arctica, stony silt adjacent to 55 60 8.13±0.09 75°45.33′ 91°12.40′ glaciofluvial delta at 55–60 m Truelove Lowland (see Dyke et al. 1991) S-433 B. mysticetus 3 — 2.9±0.09 75°41′ 84°39′ Y-1294 H. arctica, surface 3.4 ? 7.48±0.12 75°41.2′ 84°37′ I-3231 Peat ? 3.6 2.45±0.09 74°40′ 84°37′ B-15393 Driftwood, archaeological ? 3.6 2.71±0.06 S-438 Marine algae 6.7 ? 6.3±0.12 75°40′ 84°35′ B-15389 Driftwood, archaeological ? 7 3.535±0.09 Y-1295 H. arctica, M. truncata, surface 7.7 ? 8.25±0.16 75°40.8′ 84°37′ B-25032 Rangifer tarandus, archaeological ? 8 3.7±0.07 B-15390 Driftwood, archaeological ? 9 3.68±0.09 B-20781 Driftwood, archaeological ? 9 3.77±0.18 S-1313 R. tarandus, archaeological ? 9 3.85±0.10 S-431 Larix sp. or Picea sp. driftwood 11 — 5.28±0.10 75°40.1′ 84°36′ S-432 B. mysticetus 11 — 6.1±0.13 75°40.2′ 84°36.5′ B-12406 Driftwood, archaeological ? 15 4.04±0.07 B-20783 Driftwood, archaeological ? 15 4.11±0.09 Y-1296 H. arctica, surface 16 ? 8.74±0.12 75°40.2′ 84°35′ B-12405 Driftwood, archaeological ? 16 4.16±0.18 S-413 M. truncata, H. arctica, surface 23 ? 9.57±0.13 75°40′ 84°33′ S-410 M. truncata, H. arctica, surface 25 ? 8.37±0.12 75°38′ 84°30′ S-430 Peat ? 26 4.3±0.10 75°38.4′ 84°28′ S-434 M. truncata, H. arctica, surface 30 ? 8.2±0.14 75°38′ 84°26′ GSC-991 B. mysticetus 42.4 — 8.27±0.15 75°40′ 84°23′ S-428 Peat ? 57 6.9±0.12 75°38.2′ 84°26′ Y-1299 Marine shells, surface 60 ? 9.36±0.16 75°38.6′ 84°27′ TO-566 Organic marine sediment in core 21 ? 10.57±0.20 75°39′ 84°33′ TO-564 Organic marine sediment in core 4.5 ? 10.6±0.16 75°39′ 84°39′ Beta-19201 B. mysticetus 21.8 — 6.79±0.09 Beta-14819 B. mysticetus 69 — 8.92±0.14 Notes: Entries with an asterisk after the laboratory number were not used in the regressions, but were considered in drawing subjective RSL curves. All samples are from raised beaches unless otherwise indicated. Previously published geological dates are from Blake (1987, 1988), Glushankova et al. (1980), Lowdon et al. (1971), Lowdon and Blake (1975), McNeely (1989), Müller and Barr (1966), Barr (1971), and King (1991). Archaeological dates are from Helmer (1991), McCartney and Helmer (1989), McGhee (1976), and Park (1989). GSC-5548, GSC-5562, GSC-5569, and GSC-5940 are from R.B. Taylor (personal communication, 1996). Otherwise, all dates above GSC-5548 and above S-3521, and all TO dates are from the present study.
© 1998 NRC Canada
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