Ice-Push Ramparts in the George River Basin

Short Papers and Notes

ICE-PUSH RAMPARTS IN THE up to shingle size is moved significantly GEORGERIVER BASIN, and the resultant ridges are often de- LABRADOR-UNGAVA stroyed ormodified by wave actionlater in the summer.Proglacial lakes with Introduction calving ice fronts may have their shore- Fieldwork in the WhitegullLake lines modified by icebergs although the area in the Upper George River basin effect would be expected to vary with was carried out while the author was the size of the iceberg and the slope of based at the McGillSub-Arctic Re- the shore. search Laboratory, beginning inthe last The rarity of ice-push ramparts in week of the partial open water season Labrador-Ungava is possibly a reflec- in July 1963. Observations of ice-push tion of their restricted environments.In ramparts,still at that timepartially view of this and of the following discus- covered with lake ice, were made then sion it is worth while quoting Hubbard's and later in the season. These ramparts description of ice-push ramparts at are of significance when evaluating both Lake Michikamau13. modern and fossil lake shore develop- ". . . a peculiar moundof rocks along ment and when estimating the ice con- the edge of the water which provedto ditions that prevailed in past times. be characteristic of the whole shore- Ice-pushramparts, under different line of the lake. The rocks had been names1A3 have been studied in various pushed out by the ice and formed a parts of the world since 1822, which is sort of wall while over the wall moss the earliest reference in Charlesworth4. and willow grew- back of these were Subsequently two main genetically-de- swamps." terminedtypes of ice-push rampart have been recognized. Ice-push features in the First, there are those features due to Whitegull Lake Area. the push of lake ice expanding after a Lakes Whitegull and Michikamauare sufficientlysudden temperature rise. both large exposed lakes with, on the Although Hobbs5 attributes lake ram- whole, gently sloping shores. Whitegull parts in general to this process it has Lake is largely the result of damming only been demonstrated on lakes with a by the esker which cuts it off from Leif comparatively thin ice cover6,' through Lake to the north so that it spills into which temperature changecan pene- the GeorgeRiver more directly over trate rapidly. It is the process invoked rapids to the west. Eskers were traced forlake ramparts inmid-temperate byecho sounder across the lake in 1atitudesV. Far moreimportant in severalplaces; sometimes eskers near northern regions is the process whereby the water surface had been scoured by lake ice rafts ashore, sometimes climb- ice-push to form islands. ing tens of feet after strong and per- The features are best described with sistent winds during the partial open- reference to Figs. 1 and 2. The first water seasonRamparts of thistype showsa rampart built of material have been observed at Cambridge Bay, dredged from shoalwater around a bed- VictoriaIslandg and at anumber of rock island. Being madeof smaller sized other places including Baffin Island12. cobbles it is freshlydistributed and To thesetypes of rampart maybe rests at high angles, in excess of 35" in added the minor features formedby some cases. Boulders rest precariously small candling ice-chunks being driven on the crest of the ridge.The second ashore by waveslate in the partial open exampleis made up of much larger water season. In this case only material boulders and is a more stable feature.

189 190 SHORTAND PAPERS NOTES

Fig. 1. Ice-push rampart, 12-15 ft. high, on a low bedrock island near the entrance to the northwest armof Whitegull Lake

Boththese types of rampartare best is well documented11 but not seenoften developed on islands beyond extensive because the partial open water season shoals. Ramparts in general are found is very short. on islands andaround the shores of If ice rafting is held responsible for Whitegull, Raude and the larger of the ice-push features in the Whitegull area neighbouring lakes. In many cases they it might be expected that their disposi- are merely lines of boulders. The size tion would relate to theprevailing wind of theramparts wouldappear to be regime.This is notthe case in the governed by the availability of boulders. Whitegull Lake area except on Raude These, as far as lake ice is concerned, Lake southof Whitegull Lake. This lack are more plentiful ongently shelving of lee-shore orientation is probably due shores, locations which tend to protect to the fact that the partial open water the ramparts from severe wave action season in Labrador-Ungava is only during the summer. about 13 daysl5. In some cases the rampartblocks were It is interesting to note thatwhen seen some three or four feet high and the from a canoe, some of the lake ramparts bentand shattered trees found near mightbe taken for raised shorelines. many ramparts suggested a considerable Thus it may be that the “raised shore- and prolongedpressure. It was first lines” described by Low16 at Lake Mi- thought that lake ice expansion before chikamau are ice-pushramparts. In breakup might yield this effect. But, as 1960 Ives17pointed outthat Low’s raised it was later pointed out 14, the tempera- shorelines were an enigma in the light ture changes necessary for the expan- of dataon the deglaciation of the sion donot significantly penetrate George River Basin to the north. This snow-covered ice which is as thick as view is supportedby recent workls. that found during the winterin northern Certainly an intricateice dam would be Canada.Unfortunately the field party necessary to hold up a body of water arrived too late in the partialopen water 35 ft.above present lake level in the season to observe lakeice rafting ashore Michikamau 1ocalitylQ.Whether or not althoughmany ramparts still carried ice-push rampartscan be as high as lake ice (Fig. 3). However, thewriter 35 ft. can only be checked fieldby work. saw the process the following summer The problem is a puzzling one: raised in Baffin Island. Once this kind of ice shorelines inLabrador-Ungava are rafting has been seenin action there can usuallyapparent from air-photos but be no doubt in the observer’s mind that none has been identified on the photo- the necessary force can be exerted. It graphs of the Michikamau area. SH ORT PAPERS AND NOTES AND PAPERS SHORT 191

Raised shorelines and the action that timeand invokes a shortpartial of lake ice. open-water season to explain the lack Before the ice conditions which pre- of them as fossil features today. Alter- vailed on the former pro-glacial Nas- natively, a long open water season might kaupi laked7 of Labrador-Ungava can be responsible. Yet with the probably beinferred from the presence or ab- longer season prevailing today, ice push sence of fossil ice-push features on their features do not seem to suffer, though raised shorelines, itis necessary to it is truethat most are protectedby assess therelative importance of the gentlyshelving shores in contrast to various ice pushing agents andthe vari- the steephillslopes upon whichthe Nas- ables which determine their effective- kaupi shorelines developed. It would ness atany one place. Perhaps one seem that the analogy between condi- should first turn tosome modern though tions at the time of the Naskaupi lakes smallercounterparts of the Naskaupi andthe modern pro-glacial lakes of Lakes, for example the pro-glacial lakes Baffin Island cannot be carried far until around the north edgeof the BarnesIce more evidence is available from which Cap in Baffin IsIandJ". Ward12 has to infer the state of the Laurentide ice shown that the sixweek ice-free period in Naskaupi times. Certainly a definite is insufficient for wave action to destroy open-water period of some kind seems boulderramparts. However, in Baffin likely because the shorelines, both Island many of the higher lakes rarely erosional and depositional, are so well become totally free of ice and theremay developed. be small ice floes dampening the effect Indeed, Ives1? inhis evaluation of of the waves on exposedshores until conditions on the eastern shorelines of the onset of winter. Thepresence of the Naskaupilakes does not mention some lake-ice throughout the summer lake ice. He points to the lack of evi- near the Baffin Island ice caps is espe- dence of iceberg action on shorelines cially noticeable during poor summers21 and suggests the existence of a distant such as those of 1950 and 1963. ice dam and a western boundary com- By analogy it might be suggestedthat prising much dry land, rather than a the partial open water and open water pro-glacial lake relatively free from conditions on the Naskaupi pro-glacial bergs. Thusgenuinea open water lakes were often restricted to the east- season, suchas occurs in Labrador- ern sections away fromthe ice-barriers. Ungava at present, is implied. As Der- Thus Matthew2'-' favours the panice floe byshireZ2 has demonstrated, the climate to the iceberg as the operative agent at of late glacial times was probably not

Fig. 2. Rampart in eskershoalwater between the northeastand northwest arms of Whitegull Lake. 192 NOTES AND PAPERS SHORT

Fig. 3. Eastern shore of Whitegull Lake late June 1963. Rafted ice carried by rampart stands some 15 ft. above the lake. very different from that of the present. also include the mapping of these fea- Whether this inferred condition at the tures over wide areas and the gathering time of final wastage can be applied to of furtherdata on thelength of the the climate of Naskaupi times is very partial open water season in different doubtful. The distinct lakephase de- localities. mandsa major still-stand of the ice The factors involved in windcon- sheet which must have beensufficiently trolled ice-push in lakes are not very massive to dam considerable quantities different(cum grano salis) from those in of water. the sea and the two situations are not Thesteep hillsides of much of the discussedseparately byWashburnv. eastern shores of the Naskaupi lakes1' However, the different conditions on and N2 in particular, contrast with the the shoresof some arctic beaches, where gently-shelving, thoughnot too shal- ice may be forced ashore at any time of lowv, shore regions of the modern lakes the yearz3, and around the lakesof the of the plateau where ice push ramparts Labrador-Ungavaplateau, where ice have been reported. This may account push would seem to be confined to the for the absence of ice-push features on shortpartial open water season, must the fossil shoreline remnants. Thus the clearly be borne in mind during these steep hillsides provided an optimum future investigations. condition for the formation of wave cut Acknowledgements platforms, but were generally too steep The writer wishes to thank Col. P. D. for ice push ramparts to be well formed. Baird of the Department of Geography, Detritus is not easily dredgedfrom McGill University, and Mr. E. Derby- non-shelving shores and such ramparts shire of the Department of Geography, as might have been built were not out Monash University, for critically read- of the reach of wave action. In contrast, ing the first drafts of this paper. The the gently sloping shores in the lower writer's field work during the summer areas of more plentiful drift, such as the of 1963 wassupported by the McGill present Whitegull and Michikamau lake Sub-Arctic Research Laboratory. regions, haveprovided conditions fa- JAMESA. PETERSON* vourable to the formation of ice push ramparts. The critical relationships between all the factors mentioned above can only be *McGill University, Departmentof Geog- tested by field work. Suitable lakes de- raphy,Montreal 1962-64; Department of mand observation from before breakup Geography,Monash University, Clayton, until its completion.Future work should Victoria, Australia, 1965. SH OR T PAPERSSHORT NOTES AND 193

1Ice shoveridge, lake rampart, ice-push Isgarnett, D. M. and J. Peterson. 1964. The ridge, walled lake, ice terrace, ice ram- significance of glacial Lake Naskaupi 2 part, etc. in the deglaciation of Labrador-Ungava. ZHowell, J. V. ed. 1960. Glossary of geology CanadianGeographer. Vol. VIII. NO. 4 and related sciences. Washington: Ameri- pp. 173-181. can Geological Institute. 325 pp. IgTanner, V. 1944. Outlines of the geog- "tamp,D. ed. 1962. Aglossary of geo- raphy,life and customs of Newfound- graphicalterms. London: Longmans. land-Labrador. Acta Geogr. 8:l-906. 539 pp. ZOMatthew, E. M. 1961. The glacial geomor- 4Charlesworth, J. K. 1957. The Quaternary phology and deglaciation of the George era, with special reference to its glacia- River basin. Unpub. M.Sc. thesis, McGill tion. Vol. l. University,Montreal. "obbs,W. H. 1911. Requisiteconditions ZlBaird, P. D. 1964. Personal communica- for the formation of ice ramparts. Jour. tion. Department of Geography, McGill of Geol. 19:157-160. University, Montreal. sZumberge, J. H. and J. T. Wilson. 1952. Ice ZZDerbyshire, E. 1960. Glaciation and sub- push studies on Wamplers Lake, Michi- sequent climatic changes in central Que- gan.Abstract. Geol. SOC. Am. Bull. bec-Labrador:acritical review. Geog. 63:1318. Annaler. V. XLII pp. 47-61. 'i . 1953. Quantitativestudies on 23Hume, J. A. and M. Schalk. 1964. The thermal expansion and contraction of effects of ice-push on arctic beaches. Am. Lake ice. J. Geog. 61:374-383. J. Sci. 262:267-73. *Jennings, J. N. 1957. Ice action on lakes. J. Glaciol. 3:228-9. swashburn, A. L. 1947. Reconnaissance Geology of portions of Victoria Islandand adjacentregions, arctic Canada. Geol. SOC.Am. Memoir 22. pp. 76-80. ACCESS TO MEIGHEN ISLAND, loBaird, P. D. 1964. The polar world. Lon- N.W.T." don: Longmans Green. p. 67. Meighen Island (80" N. W) lies 11Tyrrel1, J. B. Ice conditions on Cana- 100" 1910. in the centre of the northwest edge of dianlakes. Trans. Can. Inst. IX. (1910) the QueenElizabeth Islands (Fig. 1) pp. 1-9. and its northerncoast fronts on the IZWard, W. H. Ice action on shores. J. 1959. ArcticOcean. Sverdrup and Peary Glaciol. 3:437. Channels, which separate Meighen Is- 13Hubbard Jr., Mrs. Leonidas. 1908. A land from Axel Heiberg andEllef Ring- woman's way through unknown Labra- nesIslands, are generallyfilled with dor. London: John Murray. 388 pp. iceduring the summermonths. The IdMuller, Fritz. 1964. Personal communica- season of maximum open water occurs tion.Professor of Geography, McGill inearly September, but at this time University,Montreal. floes of heavy polar ice move into the IjJones, K. J. 1958. Freshwater ice in channels.The island is one of those Quebec-Labrador andits utilization by never visited by surface vessels, and is aircraft. McGill Sub-Arctic Research very likely to retain this distinction for Papers, No. 4 pp. 59-87. some time as it is of little economic in- lGLow, A, P. 1895. Report on explorations terest compared with other equally in- inthe Labrador Peninsula, along the accessible islands in the western Queen Eastmain, Koksoak, Hamilton, Manicua- Elizabeth group. gan and portions of other rivers in 1892- 93-94 and 95. Geol. Surv. Can. Ann.Rep. 9 * Based on meteorologicalobservations pt. L.387 pp. recorded over three field seasons by K. C. 17Ives, J. D. 1960. Former ice-dammed lakes Arnold, Canada Department of Mines and and thedeglaciation of the middle reaches TechnicalSurveys, as part of the Geo- of the GeorgeRiver, Labrador-Ungava. graphical Branch's contributionto the Polar Geogr. Bull.14:44-70. Continental Shelf Project.