Raised Shoreline Phenomena and Postglacial Emergence in South
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Document généré le 26 sept. 2021 07:54 Géographie physique et Quaternaire Raised Shoreline Phenomena and Postglacial Emergence in South-Central Newfoundland Les lignes de rivage soulevées et l'émersion postglaciaire au centre-sud de Terre-Neuve Вoзвышeнный peльeф пoбepeжья и пocлeлeдникoвый пpиpocт cуши нa южном подерeжьe цeнтpaльнoгo Hьюфaундлeндa C. M. Tucker, D. A. Leckie et S. B. McCann Volume 36, numéro 1-2, 1982 Résumé de l'article Dans la région de Burin-Hermitage, au sud de Terre-Neuve, on retrouve deux URI : https://id.erudit.org/iderudit/032475ar types de lignes de rivage marines soulevées: des plates-formes marines DOI : https://doi.org/10.7202/032475ar entaillées dans la roche en place ainsi que des terrasses et des plages développées dans des matériaux meubles. La plupart des plates-formes datent Aller au sommaire du numéro d'avant le Wisconsinien inférieur. Une ligne de rivage rocheuse horizontale située à 4,5 ± 1,5 m, qu'on retrouve à travers la région, fut probablement formée au cours du dernier interglaciaire. Des deltas soulevés et des épandages Éditeur(s) fluvioglaciaires côtiers, associés à des plans d'eau marins qui marquent la limite marine du Wisconsinien inférieur dans la partie nord de la zone d'étude, Les Presses de l'Université de Montréal sont mis en relation avec des terrasses et des plages soulevées existant plus au sud dans la péninsule de Burin. L'altitude de ces formes sert à établir le mode ISSN régional d'émersion post-glaciaire. Il s'est produit une emersion de plus de 30 m dans le nord-ouest, alors que l'extrême-sud de la région est en phase de 0705-7199 (imprimé) submersion. 1492-143X (numérique) Découvrir la revue Citer cet article Tucker, C. M., Leckie, D. A. & McCann, S. B. (1982). Raised Shoreline Phenomena and Postglacial Emergence in South-Central Newfoundland. Géographie physique et Quaternaire, 36(1-2), 165–174. https://doi.org/10.7202/032475ar Tous droits réservés © Les Presses de l'Université de Montréal, 1982 Ce document est protégé par la loi sur le droit d’auteur. L’utilisation des services d’Érudit (y compris la reproduction) est assujettie à sa politique d’utilisation que vous pouvez consulter en ligne. https://apropos.erudit.org/fr/usagers/politique-dutilisation/ Cet article est diffusé et préservé par Érudit. Érudit est un consortium interuniversitaire sans but lucratif composé de l’Université de Montréal, l’Université Laval et l’Université du Québec à Montréal. Il a pour mission la promotion et la valorisation de la recherche. https://www.erudit.org/fr/ Géographie physique et Quaternaire, 1982, vol. XXXVI, n°* 1-2, p. 165-174, 4 fig., 2 tabl. RAISED SHORELINE PHENOMENA AND POSTGLACIAL EMERGENCE IN SOUTH-CENTRAL NEWFOUNDLAND CM. TUCKER*, D.A. LECKIE and S.B. McCANN, Department of Geography, McMaster University, Hamilton, Ontario L8S4K1. ABSTRACT Two types of raised marine RÉSUMÉ Les lignes de rivage soulevées PL3K)ME Bo idhi ι ne η ι ihi ii pe.tbeffi nooepe· shoreline features occur in the Burin- et !'emersion postglaciaire au centre-sud Mh'i υ noc.ic.icàiiiiKonbiii npupocm tvuiii nu Hermitage area of southern Newfoundland de Terre-Neuve. Dans la région de Burin- K)MCItOM noôcpokhc ια·ιιηιρα.ιι,ιιο,·ο //ι,ΐοφιΐ- — marine benches cut in bedrock, and Hermitage, au sud de Terre-Neuve, on re vnô.iciuhi. B paiione Bypnii-XepMirnijw ιο>κ- terraces and beaches developed in un trouve deux types de lignes de rivage iioio HbK>c{)ayH;uieH;ia BcrpciaioTcn .ma τιι- consolidated materials. Most of the marines soulevées: des plates-formes iia BOJBbiiiicHHOK) pe:ii»e(j)a 6cpcroBoii .m- benches are older than Late Wisconsi- marines entaillées dans la roche en pla HlI II: MOpcKHC OTMClH. HI.ipC5aillll.il.· K KO- nan, and a horizontal rock shoreline at ce ainsi que des terrasses et des plages pciiiibix nopojrax, a raK>Kc icppacbi H IIJIH- 4.5 ± 1.5 m, which occurs throughout développées dans des matériaux meu VKH. o6pa)OBaniibie Β nciaiBcp.icBiiiiix Π0- the region, was probably formed in the bles. La plupart des plates-formes datent po.iax. Bo.ibina» iaCTfa OTMCJICU Crapine, >ICM last interglacial period. Raised deltas and d'avant le Wisconsinien inférieur. Une li II01.1HHH BHCKOHCHH. a I opil !OHTa.II,HaH 6e- coastal outwash deposits graded to gne de rivage rocheuse horizontale située pcioitan JTHHHfl Hl KOpcilllhlX ΠΟρο.Τ HhICO- former sea level positions, which define à 4,5 ± 1,5 m, qu'on retrouve à travers Toii 4.5 * - 1.5 M, KOTopaa BCTpeiacTCH no the Late Wisconsinan marine limit across la région, fut probablement formée au BCCM) paHony. B03M0MCH0, oôpaioBariaci. B the northern part of the study area, are cours du dernier interglaciaire. Des del iioc.ic.iimii MC*:.ic;iiinKOBi»iii iicpno;i. B03- correlated with terraces and raised tas soulevés et des épandages fluvio BbIiUCiIiIbIC ,icjibTbi H 6cpei OBbie iianocbi OT- beaches further south on the Burin glaciaires côtiers, associés à des plans JlO)KCHHH COOTBeTClBVK)T GbIBUlCMV ypoiillK) Peninsula. The elevations of these d'eau marins qui marquent la limite MOpfl, KOTOpblH OHCp'IHBaCTCH MOpCKHMH features are used to define the regional marine du Wisconsinien inférieur dans npe/veriaMii nojjuicro BHCKOHCHHa B ccucp- pattern of postglacial emergence. More la partie nord de la zone d'étude, sont HOH qacTH ncc;ie;iycMOiO paiiona H comia- than 30 m of emergence has occurred mis en relation avec des terrasses /WCT c rcppacaMH H B03BbiuieHHbiM no6e- in the northwest, but the extreme south et des plages soulevées existant plus pc/hbCM .uijicc lia KM lia nojiyocTpoBC By- ern part of the region is undergoing au sud dans la péninsule de Burin. L'alti PHH. 3ΤΗ BOJBblUieHHOCTH HCnOJIbJVKTTCH submergence. tude de ces formes sert à établir le .T.IH oiipcac.icHiiH pel iioiia.TbHoi ο xapaKTC- mode régional d'émersion post-glaciaire. pa iioe.ie.iLMiiHKOBoro npiipocTa cyurn. Bo- Il s'est produit une emersion de plus de jicc 30 M iipupocia cyuni npoiiioniio lia 30 m dans le nord-ouest, alors que ccHcpo-iaiia.nc. MO Β naiioo.iee Hmuo'ù ia- l'extrême-sud de la région est en phase crii paiiona npoiicxo.uiT laioiuiciiiic cyUlH. de submersion. * Present address: Vehicle Mobility Section, Defence Research Establishment, Suffield, Ralston, Alberta TOJ 2NO. 166 CM. TUCKER, D.A. LECKIE and S.B. McCANN INTRODUCTION wash valley trains which radiated down major valleys from an ice marginal position well inland to the north. Raised shoreline features of various kinds at nume On this evidence he suggested the pattern of post rous localities in the Burin Peninsula and Hermitage glacial emergence shown in Figure 1A, which was sub area of south central Newfoundland (Fig. 1), have been sequently adopted by FLINT (1971, Fig. 13 — 10, p. 360). noted by several authors (JEWELL, 1939; WHITE, 1939; More recently, WIGHTMAN and COOKE (1978), in a re- VAN ALSTINE, 1948; WALTHIER, 1948; POTTER, 1949; WIDMER, 1950; BRADLEY, 1954; JENNESS, 1960; GRANT, 1975), and it is clear from their brief descrip tions that more than one open episode of marine erosion and deposition was involved in the formation of these features. It is evident that a distinction must be made between marine benches, which predate at least one period of widespread glaciation because they are cut in bedrock and overlain by glacial deposits, and beach deposits and terraces cut in unconsolidated materials which are of late- or post-glacial age. However, prior to our investigations (TUCKER 1976, 1979 a and b; TUCKER and McCANN, 1980; LECKIE, 1979; LECKIE and McCANN, in press) there had been no concerted effort to measure the elevations and examine the mor phologic and stratigraphie relations of the various shoreline fragments with a view to elucidating the rela tionships between former sea levels and ice limits throughout this part of Newfoundland. Of the earlier descriptions of raised shorelines the most complete relate to the Hermitage area, where WID- MER (1950) made excellent observations of glacial and related phenomena. He recognized that "there are probably two sets of strandlines due to two different sets of conditions. Some of the occurrences are proba bly Sangamon in age while the remainder are probably late Wisconsin in age" (WIDMER, 1950, p. 70), but Wid- mer found no evidence of tilting of the strandlines. He correctly assigned the origin of terraces and other fea tures in the northern Bay d'Espoir area (Fig. 2) to the existence of a glacially dammed lake (LECKIE and McCANN, in press) and described the evidence of a late phase of valley glaciation. However, his interpretation of late-glacial raised shoreline features along the south ern (Fortune Bay) coast of the Hermitage area was severely constrained by his adherence to the view that the zero isobase of post-glacial uplift lay north of the region (DALY, 1921 ; FLINT, 1940, 1947). This led Wid- FlGURE 1. Reconstruction of the extent and amount of postglacial mer to propose that the younger raised shorelines of the emergence in the Burin-Hermitage area (inset: location of study area). Hermitage area and also the Burin Peninsula were A. From JENNESS (1960, Fig. 8, p. 176), isobases in eastern Newfound developed in a series of very large freshwater lakes land, based upon upper levels of outwash deltas, and Figure 6 (p. 172), impounded by massive tongues of Newfoundland and map showing location of elevated alluvial terraces in eastern Newfound land. B. From WIGHTMAN and COOKE (1978, Fig. 2, p. 64), isopleths Cabot Strait ice (WIDMER, 1950, plate 9, p. 124 ; see also of postglacial emergence in Atlantic Canada. TUCKER and McCANN, 1980, Fig. 2a), which initially ex tended out to the Grand Banks.