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Little Ice Age History of Tzeetsaytsul Glacier, Tweedsmuir Provincial Park, British Columbia

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Little Ice Age History of Tzeetsaytsul Glacier, Tweedsmuir Provincial Park, British Columbia Géographie physique et Quaternaire, 2000, vol. 54, n° 2, p. 135-141, 8 fig., 3 tabl. LITTLE ICE AGE HISTORY OF TZEETSAYTSUL GLACIER, TWEEDSMUIR PROVINCIAL PARK, BRITISH COLUMBIA Dan J SMITH*, and Joseph R. DESLOGES, respectively, University of Victoria Tree-Ring Laboratory, Department of Geography, Victoria, British Columbia, V8W 3P5, and Department of Geography, University of Toronto, Toronto, Ontario M5S 1A1. ABSTRACT, 2000, vol. 54, n° 2, 8 fig., 3 tabl., 1(1), 1D. J. SMITH and J. R. DESLOGES This paper describes licheno- RÉSUMÉ Évolution du glacier de Tzeetsayt- ZUSAMMENFASSUNG Geschichte der klei- metric and dendroglaciological investigations sul, au parc provincial de Tweedsmuir (Colom- nen Eiszeit des Tzeetsaytsul-Gletschers im of Little Ice Age (LIA) deposits at Tzeetsaytsul bie-Britannique) au cours du Petit Âge glaciaire. Tweedsmuir Provincial Park, British Columbia. Glacier, Tweedsmuir Provincial Park, British Des recherches en lichénométrie et en dendro- Man hat mittels Flechtenmessungen und Den- Columbia. The glacier originates from an ice- glaciologie ont été menées sur les dépôts du droglaziologie die Ablagerungen der kleinen field on the northeast flank of Tzeetsaytsul Petit Âge glaciaire au glacier de Tzeetsaytsul, Eiszeit am Tzeetsaytsul-Gletscher im Tweeds- Peak and terminates in a moraine-dammed au parc provincial deTweedsmuir. Le glacier tire muir Provincial Park, British Columbia, lake. A stream draining the lake has incised the son origine d’un champ de glace situé sur le erforscht. Der Gletscher entsteht aus einem Eis- moraine dam and flows through nested flanc nord-est du Tzeetsaytsul Peak et se ter- feld an der Nordost-Flanke des Tzeetsaytsul moraines into a second lake. Two end mine dans un lac fermé par une moraine. Le Peak und endet in einem durch eine Moräne ein- moraines near the lower lake record separate cours d’eau qui draine le lac a incisé le barrage gedämmten See. Eine den See dränierende advances, with numerous morainic ridges morainique et coule à travers des moraines Strömung hat sich in den Moränen-Damm ein- found between the two lakes. A locally cali- emboîtées jusqu’à un deuxième lac. Deux geschnitten und fließt durch eingeschachtelte brated Rhizocarpon geographicum growth moraines frontales près du lac inférieur témoi- Moränen in einen zweiten See. Zwei Endmorä- curve was constructed and provides relative gnent de récurrences distinctes, avec de nom- nen nahe beim unteren See belegen getrennte ages for all the moraines. Absolute dates from breuses crêtes morainiques observées entre Vorstöße und man findet zahlreiche Moränen- wood fragments collected from within the les deux lacs. Une courbe de croissance de Kämme zwischen den zwei Seen. Eine vor Ort morainic debris were determined by matching Rhizocarpon geographicum étalonnée locale- geeichte Rhizocarpon geographicum Wachs- their annual growth ring patterns to a local ment a été établie et fournit l’âge relatif de toutes tumskurve wurde erstellt und sie ergibt relative Abies lasiocarpa tree-ring chronology. The les moraines. Les datations absolues sur du Alter für alle Moränen. Absolute Daten von outermost terminal moraine was deposited by bois recueillis à l’intérieur des débris moraini- innerhalb des Moränenschutts gesammelten a 17th century advance that culminated in ca. ques ont été établies en faisant correspondre le Holzfragmenten wurden bestimmt, indem man 1700. Following subsequent recession, Tzeet- modèle de croissance annuelle des cernes das Muster des jährlichen Wachstums ihrer saytsul Glacier readvanced to build a second avec la chronologie de croissance d’un Abies Ringe mit der lokalen Baumringchronologie von terminal moraine by the mid-1800s. Recession lasiocarpa local. La moraine frontale la plus Abies lasiocarpa zusammenpasste. Die äußer- of this glacier occurred within 40 years and by externe a été déposée pendant une récurrence ste Endmoräne wurde durch einen Vorstoß 1935 the glacier was beginning to calve into survenue au XVIIe siècle qui a culminé vers im 17. Jahrhundert abgelagert, der früh kulmi- the uppermost lake. The research shows that 1700. Après le recul qui a suivi, le glacier Tzeet- nierte, etwa um 1700. Nach dem folgenden the most recent LIA advance of Tzeetsaytsul saytsul a réavancé et construit une seconde Rückzug machte der Tzeetsaytsul-Gletscher Glacier was not the most extensive, and that moraine vers la moitié du XVIIIe siècle. Le recul wieder einen Rückvorstoß und baute eine multiple events characterized the late-LIA. du glacier s’est produit dans les 40 années qui zweite Endmoräne gegen die Mitte des 18. Jahr- Application of the Rhizocarpon growth curve ont suivies et, vers 1935, il commençait à vêler hunderts. Das Zurückweichen dieses Glet- indicates a previously unreported 17th century dans le lac le plus élevé. Les recherches mon- schers geschah über 40 Jahre und um 1935 advance at other glaciers in the region. These trent que la récurrence la plus récente du glacier begann der Gletscher in den höchsten See zu findings serve to reinforce the synchroneity of Tzeetsaytsul au Petit Âge glaciaire n’a pas été kalben. Die Forschungen zeigen, dass der jüng- late-LIA glacier fluctuations within the coastal la plus importante et que de multiples événe- ste Vorstoß des Tzeetsaytsul-Gletschers in der cordillera of NW North America suggesting ments ont caractérisé le Petit Âge glaciaire kleinen Eiszeit nicht der extensivste war und that they record regional climate forcing. supérieur. L’application de la courbe de crois- dass vielerlei Ereignisse die späte kleine Eiszeit sance du Rhizocarpon fait ressortir une récur- charakterisierten. Die Anwendung der Rhizo- rence jamais rapportée pour d’autres glaciers carpon-Wachstumskurve zeigt einen zwar nicht de la région au XVIIe siècle. Ces résultats ren- belegten Vorstoß an anderen Gletschern der forcent le concept du synchronisme des fluc- Region im 17. Jahrhundert. Diese Ergebnisse tuations glaciaires survenues au Petit Âge bestärken den Synchronismus der glazialen glaciaire supérieur à l’intérieur de la Cordillère Fluktuationen in der späten kleinen Eiszeit de la côte du nord-ouest de l’Amérique du Nord, innerhalb der Küsten-Kordilleren von NW-Nord- reflétant ainsi un forçage climatique à l’échelle amerika und lassen annehmen, dass sie eine régionale. regionale Klima-Verstärkung belegen. Manuscrit reçu le 17 mai 1999 ; manuscrit révisé accepté le 29 mars 2000 * E-mail address: [email protected] 136 D. J. SMITH and J. R. DESLOGES INTRODUCTION C o Tree-ring m 1065 sample site p The mountains of coastal British Columbia record height- a British s ened glacial and geomorphic activity during the Little Ice Age 1065 s Columbia Moraine C 1375 r (LIA) (Ryder and Thomson,1986). Inaugurated by cooler and 1375 e Study Icefield e Area wetter conditions in the 13th century (Mathewes, 1985; Clague 1525 k Vancouver Pa and Mathewes, 1996), the LIA persisted until climatic warming rk Forest cover 52¡35' B 1675 o in the 20th century resulted in glacier recession beginning ca. u n Lower elevationsda in metres 1860 (Evans and Clague, 1994). Records from coastal British ry Tzeetsaytsul Lake ry a Columbia and nearby Alaska indicate that there were three k r d a n u P main episodes of LIA glacial activity (Wiles et al., 1999 ; Luck- o 5 Tweedsmuir 2 B 1825 5 1 Provincial man and Villalba, in press). In the early-LIA, radiocarbon and Upper Park 80 dendrochronological evidence illustrates that glaciers 19 Tzeetsaytsul Lake 5 advanced throughout the 13th and 14th centuries (Ryder and 3 21 2 Thomson, 1986; Ryder, 1987; Desloges and Ryder, 1990; 2 8 Tzeetsaytsul 5 1525 1825 5 Wiles et al., 1999). This episode was followed by a hiatus, until Glacier 7 3 1 late-LIA glacial advances in the 17th and 19th centuries (Ryder 52¡34' Tzeetsaytsul South 675 and Thomson, 1986; Ryder, 1987; Desloges and Ryder, 1990; Peak 1 Glacier 24 Clague and Mathewes, 1996; Calkin et al., 1998). N 40 In this paper we present a late-Little Ice Age history of 0 0.5 1.0 km Tzeetsaytsul Glacier1 located in southwest Tweedsmuir Pro- vincial Park, British Columbia (52° 34' 30" N; 126° 22' W; 126¡23' 126¡22' 126¡21' 126¡20' Fig. 1). This history is based on lichenometic and dendrogla- ciological investigations undertaken during the summer of FIGURE 1. Map showing the study site in the central coast region of 1997. Previous work in this region showed that most LIA ter- British Columbia. minal moraines date from the period between 1860 and Carte de localisation du site à l’étude dans la région côtière centrale de la Colombie-Britannique. 1900 (Desloges, 1987; Desloges and Ryder, 1990). Our data supplements these observations, adding to our knowledge A single, subdued terminal moraine skirting the south of the LIA in coastal British Columbia. shore of lower Tzeetsaytsul Lake marks the local limit of the LIA advance (Position 1, Fig. 4). The crest of the moraine is STUDY SITE well-rounded and sits ca. 2 m above the lake surface. The moraine appears more weathered than those upvalley and Tzeetsaytsul Glacier is located in the Kitimat Ranges of has a patchy cover of trees, shrubs and soil, and is charac- the British Columbia Coast Mountains. Peaks in the area are terized by large Rhizocarpon geographicum thalli. Immedi- composed of Hazelton Group andesitic volcanic rocks (Tip- ately upvalley, nested within 30 m of the terminal moraine is per, 1963) and flank the edge of the Interior Plateau erosion a concentric, ‘fresh-appearing’ moraine deposited by a later surface (Baer, 1973). Tzeetsaytsul Peak (2682 m asl) likely advance (Position 2, Fig. 4). The sharp-crested and unvege- persisted as a nunatak (above 1980 m asl) during Wiscon- tated moraine crest sits ca. 6 m above the lake surface. Five sinan glaciation (Baer, 1973). prominent and numerous smaller moraines occur upvalley Tzeetsaytsul Glacier is one of two outlet glaciers that and record the subsequent retreat of Tzeetsaytsul Glacier originate from a high-elevation icefield (ca.
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