The Quaternary Geologic History of the Canadian Rocky Mountains

The Canadian Rocky Mountains figured prominently during the glacial history of western Canada. First as a western limit or boundary to the Laurentide Ice Sheet, second as an eastern margin of the Cordilleran Ice Sheet, and finally as a centre of local Montane ice. Throughout the Quaternary, complex interactions of glacier ice from these three ice sources markedly changed the physical form of the Rocky Mountains, Trench and Foothills areas. Investigations into the Quaternary history of this region have been ongoing since the beginning of the last century. Since about 1950, the number of studies performed in this area have increased significantly. This paper briefly reviews the historical accomplishments of Quaternary work in the region up to the period of about 1950. From this time to the present, individual study efforts are examined in detail according to the three geographic regions: 1) the northern Rocky Mountains (from the Liard Plateau south to the McGregor Plateau), 2) the central Rocky Mountains (from the McGregor Plateau south to the Porcupine Hills) and 3) the southern Rocky Mountains (from the Porcupine Hills south to the international border). In the northern region, geologic data suggest a maximum of two Rocky Mountain glaciations and only one Laurentide glaciation and no ice coalescence. In the central region, three of four Rocky Mountain events, and at least two Laurentide events are known. Only in the central region is there good evidence for ice coalescence, but the timing of this event is not clearly established. In the south, at least three Rocky Mountain episodes and a variable number of Laurentide episodes are recognized. There is no evidence for ice coalescence. A number of facts support the proposal that Cordilleran ice crossed the Continental Divide and joined with local Montane ice at several locations. However, this expansion of western ice occurred before the Late Wisconsinan in all areas but Jasper. In general, the chronological data presented suggest that the Late Wisconsinan glaciation in the Rocky Mountains was a short-lived event which started around or after 20 ka years ago and ended before 12 ka ago.Les montagnes Rocheuses ont constitué un cas particulier au cours de l'évolution glaciaire de l'ouest du Canada. Elles ont d'abord formé la limite occidentale de l'Inlandsis laurentidien, puis la limite orientale de l'Inlandsis de la Cordillère et finalement le centre d'une glaciation alpine locale. Tout au long du Quaternaire, les interactions complexes des glaces à partir de ces trois sources ont modifié de façon sensible l'aspect physique des Rocheuses, du sillon et du piémont. Les études sur l'évolution géologique de la région ont commencé au début du siècle dernier; beaucoup plus nombreuses depuis 1950, elles se sont également diversifiées. On résume d'abord les réalisations jusqu'aux années 50, puis on se penche plus particulièrement sur les travaux accomplis depuis lors dans : 1) la partie septentrionale (du plateau du Liard au plateau du McGregor, au sud); 2) la partie centrale (du plateau du McGregor aux collines Porcupine, au sud); et 3) la partie méridionale (des collines Porcupine à la frontière des É-U., au sud). Dans la partie septentrionale, les données géologiques montrent l'existence d'au plus deux glaciations issues des Rocheuses, une seule glaciation laurentidienne et aucune coalescence des glaces. Dans la partie centrale, on reconnaît l'existence de trois ou quatre glaciations issues des Rocheuses et au moins deux glaciations d'origine laurentidienne. On y observe des indices sur la coalescence des glaces, mais on ne sait pas exactement quand elle s'est produite. Dans le sud, on reconnaît l'existence d'au moins trois glaciations issues des Rocheuses et d'un nombre variable de glaciations d'origine laurentidienne. Il n'y aurait pas eu de coalescence. Un certain nombre de faits appuient l'hypothèse selon laquelle les glaces cordillérennes auraient traversé la ligne de partage des eaux en plusieurs points pour se joindre aux glaces alpines locales. Cependant, cette extension des glaces venant de l'ouest s'est produite avant le Wisconsinien supérieur dans tous les secteurs, sauf à Jasper. De façon générale, les données chronologiques indiquent que la glaciation du Wisconsinien supérieur a été de courte durée dans les Rocheuses (de 20 ka à 12 ka environ).Die kanadischen Rocky Mountains stellen einen Sonderfall in der glazialen Geschichte von Westkanada dar. Zuerst als eine westiiche Grenze oder Trennungslinie zur laurentidischen Eisdecke, dann als ein ôstlicher Rand der Kordilleren-Eisdecke, und schlieBlich als das Zentrum einer lokalen alpinen Vereisung. Während des ganzen Quaternärs haben komplexe Interaktionen von Gletschereis aus diesen drei Eisquellen die physikalische Form der Rocky Mountains, der Trench und Foothill-Gebiete signifikant veràndert. Untersuchungen der Quatemàr-Geschichte dieses Gebiets finden seit dem Beginn des letzten Jahrhunderts statt. Dieser Aufsatz gibt einen kurzen Ùberblick ùber die historischen Leistungen der Arbeit zum Quaternàr in dem Gebiet bis in die 50ger Jahre. Von diesem Zeitpunkt an bis heute werden individuelle Forschungs-bemùhungen im Detail untersucht und zwar zu drei geographischen Gebieten: nôrdlichen, zentralen und sûdlichen Rocky Mountains. Im nôrdlichen Gebiet weisen die geologischen Daten auf maximal zwei Rocky Mountain-Vereisungen und nur eine laurentidische Vereisung und auf keinen Eiszusammen-schluB. Im mittleren Gebiet sind drei von vier Rocky Mountain-Vereisungen und mindesten zwei laurentidische Vereisungen bekannt. Nur im mittleren Gebiet findet man einen klaren Nachweis fur EiszusammenschluB aber die Zeit fur diesen Vorgang kann nicht klar bes-timmt werden. Im Sùden kônnen mindestens drei Rocky Mountain-Vereisungen und eine variable Zahl von laurentidischen Vereisungen erkannt werden. Es gibt keinerlei Hinweis auf EiszusammenschluB. Eine Reihe von Fakten stùtzen die These, daB Eis von den Kordil-leren die Wasserscheidelinie ùberquerte und sich an einigen Plàtzen mit lokalem alpinem Eis vereinigte. Jedoch geschah dièse Ausdehnung westlichen Eises vor dem spâten Wisconsinum in alien Gebieten auBer in Jasper. Im allgemeinen zeigen die vorgelegten chronologischen Daten, daB die Spàt-Wisconsinum-Vereisung in den Rocky Mountains ein kurzlebiges Ereignis war, das vor etwa 20 ka Jahren oder danach begann und vor 12 ka Jahren endete

Soil Development in Quaternary Glacial Deposits, Waterton Park Area, Southwestern Alberta

Pedological investigations in the Waterton Park area provide a useful means of testing subdivisions of Quaternary glacial deposits based on geomorphic relations. Soils in the region, however, including Podzols, Brunisols, Luvisols, and Chernozemics, also reflect the influence of soil forming factors other than time. Nonetheless, a chronosequence can be established by comparing time-diagnostic properties of soils on different geomorphic units in areas with similar climate, vegetation, slope and parent material. Properties thought to be most diagnostic of relative soil age include thickness and degree of clay buildup in B horizons and two soil development indices which average degree of development of a number of properties. Pédologie and geomorphic data suggest surface deposits include mountain tills of three or four separate advances and continental tills of two separate advances. Mountain tills are tentatively correlated with the Late Wisconsinan (about 18 ka BP), Late and or Early Wisconsinan (about 100 to 65 ka BP). Late lllinoian (about 200 to 132 ka BP). and Early lllinoian and/or pre-lllinoian (about 400 to 700+ ka BP), whereas continental tills are tentatively correlated with the Late Wisconsinan and Late lllinoian deposits of the U.S. Midcontinent.Les recherches pédologiques menées dans la région du parc Waterton ont permis de vérifier les subdivisions des dépôts glaciaires quaternaires fondées sur les relations géomorphologiques. Les sols de la région, incluant les podzols, les brunisols, les luvisols et les sols chernozémiques, reflètent également l'influence d'autres facteurs de formation que le temps. On peut tout de même établir une chronoséquence en comparant les propriétés relatives au temps des sols développés sur différentes unités géomorphologiques situées dans des régions dont le climat, la végétation, les pentes et le matériau parental sont similaires. Les propriétés considérées comme étant les plus indicatives de l'âge relatif des sols comprennent l'épaisseur et le degré d'accumulation d'argile dans les horizons B. Deux indices de développement de sols, qui font la moyenne du degré d'évolution d'un certain nombre de propriétés, fournissent aussi des indications relatives à l'âge. Les données pédologiques et géomorphologiques laissent croire que les dépôts de surface comprennent des tills de montagne de trois ou quatre glaciations distinctes et des tills d'origine continentale de deux glaciations distinctes. Les tills de montagne sont à titre d'essai mis en corrélation avec le Wisconsinien supérieur (environ 18 ka BP), le Wisconsinien supérieur ou le Wisconsinien inférieur (environ 100 à 65 ka BP), l'Illinoien supérieur (environ 200 à 132 ka BP), et l'Illinoien inférieur ou le pré-lllinoien (environ 400 à 700 + ka BP), tandis que les tills d'origine continentale sont mis en corrélation avec les dépôts du centre des États-Unis datant du Wisconsinien supérieur et de l'Illinoien supérieur.Pedologische Forschungen, die im Gebiet des Waterton-Parks durchgefùhrt wurden, erlaubten die Unterteilungen der glazialen Ablagerungen im Quaternâr, die sich auf geomorphologische Beziehungen stûtzen, zu ùberprùfen. Die Bôden des Gebiets, einschliesslich der Podsole, der Brunisole, der Luvisole und der Chernozemiks, spiegeln auch den Einfluss anderer bodenbildender Faktoren als der Zeit. Dennoch làsst sich eine Chronosequenz erstellen, indem man zeitdiagnostische Eigenschaften von Bôden in verschiedenen geomorphischen Einheiten vergleicht, in Gebieten, deren Klima, Vegetation, Abhânge und ursprùngliches Material gleichartig sind. Zu den Eigenschaften, von denen man glaubt. dass sie am besten das relative Alter der Bôden anzeigen, gehôren die Dicke und der Akkumulationsgrad des Tons in den B-Horizonten. Zwei Anhaltspunkte zu der Entwicklung der Bôden, die den Durchschnitt des Entwicklungsgrades einer bestimmten Zahl von Eigenschaften ermitteln, liefern auch Hinweise, das Alter betreffend. Die pedologischen und geomorphologischen Daten lassen vermuten, dass die Oberflâchen-Ablagerungen Berg-Tills von drei oder vier verschiedenen Vereisungen enthalten. Die Berg-Tills hat man probeweise in Beziehung zum spàten Wisconsinan (etwa 18 ka v.u.Z.), dem spâten und/oder frùhen Wisconsinan (etwa 100 bis 65 ka v.u.Z.), dem spàten IIlinoium (etwa 200 bis 132 ka v.u.Z.) und dem frùhen lllinoium und/oder prâ-lllinoium (etwa 400 bis 700+ ka v.u.Z.) in Beziehung gebracht, wàhrend die Tills kontinentaler Herkunft mit den Ablagerungen des Zentrums der Vereinigten Staaten korreliert werden, die aus dem spàten Wisconsinan und dem spàten lllinoium stammen

The Paleoecological Record of 6 ka BP Climate in the Canadian Prairie Provinces

Synthesis of available paleoecological studies in the Prairie provinces of Canada indicates that although the peak in postglacial aridity that characterized early Holocene climate of the western foothills and plains had passed, conditions remained warmer and drier than present throughout the region ca. 6000 yr BP Compared to today, treeline elevations were higher and alpine glaciers were reduced in size in the Rocky Mountains, lake levels were lower over much of the Interior Plains, and the grassland and boreal forest ecozones extended north of their present positions. Forest fires were more prevalent ca. 6000 yr BP than they are today, aiding westward migration of jack pine (Pinus banksiana) through the boreal forest and increasing the area occupied by grassland in boreal and montane forest regions. Attempts to quantify the magnitude of 6 ka temperature and precipitation differences have produced variable results, but suggest that mean annual temperature was 0.50°C to 1.50°C higher than today (summer temperature may have been up to 3°C higher) and mean annual precipitation was reduced by 65 mm (or summer precipitation was reduced by 50 mm), compared to present. The nature and scale of these changes suggests that a vigorous zonal atmospheric circulation pattern, similar to that of the 1930s but shifted northward, prevailed at 6 ka.La synthèse des études paléoécologiques montrent qu'à 6 ka le maximum d'aridité, qui caractérisait l'Holocène inférieur, avait été atteint, mais le climat demeurait plus chaud et plus sec que maintenant dans toute la région. Les différentes limites des arbres étaient plus élevées qu'aujourd'hui et la superficie des glaciers alpins étaient plus petite, les niveaux lacustres étaient moins élevés dans la plus grande partie des plaines intérieures et les écozones des Prairies et de la forêt boréale s'étendaient plus au nord qu'aujourd'hui. Les feux de forêt étaient plus fréquents à 6 ka qu'actuellement, ce qui a favorisé la migration du pin gris (Pinus banksiana) vers l'ouest à travers la forêt boréale et accru la superficie de la prairie dans les zones de forêts boréale et alpine. Les essais faits dans le but de mesurer l'ampleur des différences de températures et de précipitations à 6 ka ont donné des résultats variables, mais montrent que la température était de 0,5 à 1,5°C plus élevé que maintenant (avec une température estivale jusqu'à 3°C plus élevée) et les précipitations annuelles moyennes étaient de 65 mm inférieures (avec des précipitations estivales de 50 mm inférieures) à maintenant. La nature et le degré des changements laissent croire qu'une forte circulation atmosphérique zonale, semblable à celle des années 1930, mais plus nordique, existait à 6 ka.Die Synthèse der verfùgbaren palâoôkologischen Studien in den Prârie-Provinzen Kanadas zeigt, daf3 das Klima in der ganzen Region um etwa 6000 Jahre v.u.Z. warmer und trockener als gegenwârtig blieb, wenn auch das Maximum an postglazialer Trockenheit, welches im frùhen Holozàn das Klima der westlichen Gebirgsauslâufer und Ebenen charakterisierte, vorùber war. Verglichen mit heute waren die Baumgrenzen hôher und die alpinen Gletscher in den Rocky Mountains kleiner, die Seehôhen waren niedriger im grôBten Teil der inneren Ebenen, und die Ôkozonen von Grasland und nôrdlichem WaId erstreckten sich weiter nôrdlich als heute. Waldbrânde traten um etwa 6000 v.u.Z. hâufiger als gegenwârtig auf und haben so die Westwàrtswanderung von Graukiefer (Pinus banksiana) durch den nôrdlichen WaId begùnstigt und die Graslandflàchen in den Gebieten des nôrdlichen und alpinen Waldes vergrôBert. Versuche, den Umfang der Unterschiede in Temperatur und Niederschlàgen um 6 ka zu bestimmen, ergaben wechselnde Ergebnissse, doch zeigen sie, daB die durchschnittliche jâhrliche Temperatur 0.5° C bis 1.50C hôher als gegenwârtig war (die Sommertemperatur dûrfte bis zu 3°C hôher gewesen sein) und die durchschnittlichen jâhrlichen Niederschlâge waren um 65 mm geringer (oder die Sommer-Niederschlàge waren um 50 mm geringer) verglichen mit heute. Die Natur und der Grad dieser Wechsel lassen vermuten, daB eine krâftige zonale atmosphàrische Strômung, àhnlich der von den 1930 iger Jahren aber nôrdlicher gelagert, um 6 ka vorherrschte

Climate change impact on the hydrological functioning of mountain lakes: a conceptual framework

Mountain lakes are distinctive water bodies that attract the great attention of researchers. They not only serve as a crucial water resource for the inhabitants of the upland regions but also as an important destination for millions of tourists who are attracted by the beauty of these water bodies. With the increasing concern about global warming, mountain lakes are experiencing changes in their hydrological processes and meanwhile can act as reflectors of those changes. Specifically, due to the fragility of these water bodies, understanding the consequences is significant as it can help to find out whether climate change causes degradations in lake hydrological functioning. The interactions of hydrological processes in mountain lakes with external drivers are usually hard to explain explicitly owing to their complexity. To deal with that problem, scholars tend to use conceptual frameworks, which help to reveal the dependence of a lake on particular hydrologic factors. To identify factors influencing lake hydrological function and their sensitivity to changing climate, a literature analysis was undertaken. The focus was on the Canadian Rocky Mountains where 5155 water bodies were identified using GIS. The main literature sources used to identify factors influencing lake hydrologic function were peer-reviewed articles and books. In total, 10 natural drivers critical for lake hydrological function and 2 main reflectors of climate change impacts on mountain lakes as well as 38 additional sub-factors that characterize each of the factors and reflectors, were identified. Based on that, a conceptual framework for mountain lake hydrological functioning was developed. The major problem that affected the thorough testing of the conceptual framework was a limited number of observations across lakes in the research area. Nevertheless, the conceptual framework is flexible and might be tested across many mountainous regions worldwide that experience climatic changes. Such an opportunity can be realized through the use of quantitative statistical techniques available for large datasets. Overall, the conducted research stresses the problem of a poor degree of hydrological exploration of lakes in mountain regions and presents a useful approach to represent complex interactions of natural drivers and intra-lake processes under rising temperatures

Late-Quaternary Stratigraphy, Pedology and Paleoclimatic Reconstruction of the Cremer Site (24SW264), South-Central Montana : A Geoarchaeological Case Study

This study utilizes a multidisciplinary research approach integrating the sciences of archaeology, geology, pedology and paleoclimatology. Deeply stratified and radiocarbon dated sedimentary sequences spanning the last 10,000 yr B.P. are reported for the Cremer site (24SW264), south-central Montana. Previous investigations at the site revealed an archaeological assemblage with Early Plains Archaic through Late Prehistoric period affiliations. Expanded testing of the site integrates the existing cultural record with new data pertaining to Holocene environmental changes at this northwestern Great Plains locality. Detailed pedological descriptions were made along three trenches excavated at the site. The combined soil-stratigraphic record indicates that distinct intervals of relative landscape stability and soil development occurred at the site at ca. 10,000 yr B.P., 7,500 yr B.P. and intermittently throughout the last ca. 6,000 yr B.P. Periods of significant landscape instability (upland erosion and valley deposition) occurred immediately following each of the early Holocene soil forming intervals identified above, and episodically throughout the middle to late Holocene. The impetus for early Holocene environmental instability is attributed to generally increased aridity on the northwestern Great Plains. Comparative analyses of site data with both regional environmental proxy records and numerical models of past climates (General Circulation and Archaeoclimatic models) are made to test the findings from the Cremer site. The collective paleoenvironmental evidence indicates that the period of maximum post-glacial warming and aridity occurred at the Cremer site during the early Holocene period (prior to ca. 6,000 yr B.P.). These data also indicate that the existing archaeological assemblage from the site is younger than ca. 6,000 yr B.P., although future excavations may reveal cultural sequences associated with the earliest dated soils at the site. This geoarchaeological study of the Cremer site should contribute to a much needed research base in this sparsely studied region

Paleovegetation Reconstruction from Soil Phytoliths of a Ceremonial Site Complex at Maok-Skoistch on the Red Deer River, Alberta, Canada

Maok-skoistch (Nitsitapii for Sacred Red Rock Place) is in the dry mixed grasslands of southwestern Alberta. It sits on a horseshoe bend of the Red Deer River approximately 40 kilometers from its confluence with the South Saskatchewan River. This area contains numerous stone constructions associated with First Nations groups and their ancestors. The purpose of this study is to investigate the paleovegetation of this area to understand local and regional environmental changes. A secondary purpose is to try to detect human influence on paleovegetation. I used phytoliths extracted from two sediment columns and the modern surface as a vegetational and environmental proxy. A sediment column extracted from a depression, or slough, on the upland prairie begins circa 5700 cal BP and provides data on the regional paleovegetation. A second column from a wooded riparian coulee in the river valley (a micro-environment) begins circa 3440 cal BP and records local vegetational changes. There is little available literature on phytoliths of the Canadian Prairies, to say nothing of the micro-environments within the region such as riparian coulees. I created a morphotype reference collection from the available relevant literature on grassland and forest phytolith assemblages. I detail how I developed a phytolith extraction protocol tailored to the sampled sediments, including the pitfalls I encountered. This section may be of use to those who have not extracted phytoliths before. I used environmental index formulae to investigate paleovegetational dynamics. I used Principal Components Analysis to find similar assemblages and to compare them to modern surface assemblages. The paleovegetation at the upland slough conforms to the synoptic record of environmental changes. I found the river valley coulee paleovegetation responds most strongly to local conditions. Soil moisture appears to be the strongest factor in paleovegetational changes. Interestingly, the coulee record may be responsive to precipitation and glacial meltwater changes in the Rockies where the Red Deer River begins. The phytolith knowledge base in the Canadian Prairies is not robust enough yet to achieve the resolution necessary to detect human influences on paleovegetation. I outline some ideas and avenues for future research to remedy this situation

AEOLIAN DUNE FIELDS OF KANSAS AND THEIR RESPONSE TO LATE-QUATERNARY DROUGHT

Aeolian dune fields are ubiquitous features of the North American Great Plains, and contained within their stratigraphy are important records of changes in prehistoric climate. Using absolute dating techniques, researchers can determine the timing of past dune field activity, which in many cases, is the result of drought. Based on a drought-aeolian activity relationship, the timing of past dune activity can, therefore, be used as a proxy for prehistoric drought. This dissertation presents three chronologies of dune activity from understudied dune fields in Kansas. Each chronology has been established using new optically stimulated luminescence ages, which in total account for nearly 25% of the total luminescence ages reported from all U.S. Great Plains dune fields. In general, dune activity in Kansas is coeval with that recorded throughout the Great Plains, but, in particular, Kansas dunes were active during defined periods of drought recorded in other regional proxies

Hillslope sediments and landscape evolution in Wanuskewin Heritage Park : a geoarchaeological interpretation

Wanuskewin Heritage Park is situated approximately three kilometres north of the City of Saskatoon, Saskatchewan and is the location of 19 precontact archaeological sites. This study examines hillslope sediments and processes at four of the archaeological sites: Cut Arm, Meewasin, Amisk, and Thundercloud. The Cut Arm and Meewasin sites are in the South Saskatchewan River valley and the Amisk and Thundercloud sites are in the Opimihaw Creek valley. The Opimihaw Creek is a tributary of the South Saskatchewan River. The record of postglacial hillslope development is complex and fragmentary because not all erosional and depositional events are preserved at each of the study sites. However, the physical characteristics of the soil and sediment coupled with radiocarbon dates and dates from diagnostic cultural material indicate general trends. Hillslope activity began before 5.42 ± 0.12 ka BP in the Opimihaw Valley and 3.864 ± 0.055 ka BP in the South Saskatchewan Valley. Opimihaw Valley hillslope activity began during the Altithermal period, a period of aridity and warm temperatures between approximately 9 ka BP and 4 ka BP. In both valleys, numerous but weakly developed buried soils separated by hillslope sediment record repeated episodes of slope erosion and deposition between approximately 4.5 ka BP and 3.5 ka BP. Comparison with prairie lake sediments indicates this phase of slope erosion corresponds to a climatic change from the dry conditions of the Altithermal to a period of maximum Holocene humidity (ca. 4.5 ka BP to 3 ka BP). In addition, thin intermittent weakly developed soils are generally overlain by thicker soil profiles. The thicker soils suggest longer periods of nondeposition, landscape stability and soil formation and thus, a reduction in the frequency of hillslope erosion and deposition. This reduction in slope activity occurred after approximately 2 ka BP. Prairie paleoenvironmental data suggest the longer periods of landscape stability are related to moister climatic conditions and increased vegetation cover. Lastly, poorly sorted debris flow sediments ranging in size from clay to boulders are generally overlain by fine-grained sediments deposited from overland flow. Therefore, in addition to a reduction in slope activity there is a decrease in the competence of the slope processes in these stratigraphic sequences