DOCSLIB.ORG

The Early Wisconsinan History of the Laurentide Ice Sheet

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Early Wisconsinan History of the Laurentide Ice Sheet Document généré le 30 sept. 2021 19:59 Géographie physique et Quaternaire The Early Wisconsinan History of the Laurentide Ice Sheet L’évolution de la calotte glaciaire laurentidienne au Wisconsinien inférieur Geschichte der laurentischen Eisdecke im frühen glazialen Wisconsin Jean-Serge Vincent et Victor K. Prest La calotte glaciaire laurentidienne Résumé de l'article The Laurentide Ice Sheet L'identification, surtout en périphérie de l'inlandsis, de dépôts glaciaires que Volume 41, numéro 2, 1987 l'on croit postérieurs à la mise en place de sédiments non glaciaires ou de paléosols datant de l'interglaciaire sangamonien (phase 5) et antérieurs aux URI : https://id.erudit.org/iderudit/032679ar sédiments non glaciaires ou des sols mis en place au Wisconsinien moyen DOI : https://doi.org/10.7202/032679ar (phase 3) a amené de nombreux chercheurs à supposer que la calotte laurentidienne s'est d'abord développée au Sangamonien ou au Wisconsinien inférieur (phase 4). On passe en revue les différentes preuves associées au Aller au sommaire du numéro début de la formation de la calotte glaciaire wisconsinienne recueillies au Canada et au nord des États-Unis. En l'absence quasi généralisée de données géochronométriques sûres pour déterminer l'âge des dépôts glaciaires datant Éditeur(s) probablement du Sangamonien ou du Wisconsinien inférieur, on peut aussi bien supposer, pour une période donnée, que les glaces ont entièrement envahi Les Presses de l'Université de Montréal une région ou en étaient tout à fait absentes. En tenant pour acquis (?) que la calotte laurentidienne était en fait très étendue au Wisconsinien inférieur, on ISSN présente une carte montrant son étendue maximale et un tableau de 0705-7199 (imprimé) corrélation entre les unités glaciaires. Les glaciers postérieurs au Sangamonien 1492-143X (numérique) sensu stricto (sous-phase 5e) et antérieurs au Wisconsinien moyen sont généralement plus étendues qu'au Wisconsinien supérieur (phase 2). La géométrie de la marge glaciaire et les quelques données sur la direction de Découvrir la revue l'écoulement montrent que les inlandsis du Wisconsinien inférieur et du Wisconsinien supérieur se sont développés de façon similaire. On présente enfin un modèle hypothétique de croissance de la calotte laurentidienne après Citer cet article le dernier interglaciaire. Vincent, J.-S. & Prest, V. K. (1987). The Early Wisconsinan History of the Laurentide Ice Sheet. Géographie physique et Quaternaire, 41(2), 199–213. https://doi.org/10.7202/032679ar Tous droits réservés © Les Presses de l'Université de Montréal, 1987 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, 1987, vol. XLI, n° 2, p. 199-213, 4 fig. THE EARLY WISCONSINAN HISTORY OF THE LAURENTIDE ICE SHEET* Jean-Serge VINCENT and Victor K. PREST, Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8. ABSTRACT The identification, particularly RÉSUMÉ L'évolution de la calotte glaciaire ZUSAMMENFASSUNG Geschichte der at the periphery of the ice sheet, of glacigenic laurentidienne au Wisconsinien inférieur. laurentischen Eisdecke im frùhen glazialen sediments thought to postdate nonglacial L'identification, surtout en périphérie de l'in­ Wisconsin. Zahlreiche Autoren sind zu der sediments or paleosols regarded as having landsis, de dépôts glaciaires que l'on croit Annahme gekommen, dap die laurentische been laid down sometime during the San­ postérieurs à la mise en place de sédiments Eisdecke wàhrend des Sangamoniums und/ gamonian Interglaciation (stage 5) and non glaciaires ou de paléosols datant de I1In- oder des frùhen glazialen Wisconsin (Phase thought to predate nonglacial sediments or terglaciaire sangamonien (phase 5) et an­ 4) zu wachsen anting. Dièse Annahme stùtzt soils reckoned to be of Middle Wisconsinan térieurs aux sédiments non glaciaires ou des sich auf die Identifizierung glacialer Sedi- age (stage 3), has led numerous authors to sols mis en place au Wisconsinien moyen mente, die man fur alter als nichtglaziale propose that the Laurentide Ice Sheet initially (phase 3) a amené de nombreux chercheurs Sedimente oder Paleobôden halt, die ihrer- grew during the Sangamonian and/or the Early à supposer que la calotte laurentidienne s'est seits irgendwann wàhrend der Intergtazialzeit Wisconsinan (stage 4). The evidence for the d'abord développée au Sangamonien ou au des Sangamoniums (Phase 5) abgelagert beginning of the Wisconsinan ice sheet in Wisconsinien inférieur (phase 4). On passe worden sind und vermutlich nichtglazialen various areas of Canada and the northern en revue les différentes preuves associées Sedimenten oder Bôden, die der mittleren United States is briefly reviewed. The general au début de la formation de la calotte glaciaire glazialen Wisconsin-Zeit (Phase 3) zugeord- absence of sound geochronometric frame­ wisconsinienne recueillies au Canada et au net werden, vorausgehen. Die Belege fur den works for potential Sangamonian or Early nord des États-Unis. En l'absence quasi gé­ Beginn der Wisconsin-Eisdecke in verschie- Wisconsinan glacial deposits has led to a néralisée de données géochronométriques denen Gebieten Kanadas und der nôrdlichen situation where in most areas it can be argued, sûres pour déterminer l'âge des dépôts gla­ Vereinigten Staaten wird kurz zusammen- depending on one's interpretation, that ice ciaires datant probablement du Sangamonien gefapt. Das volkommene Fehlen eines ges- completely inundated or was completely ab­ ou du Wisconsinien inférieur, on peut aussi icherten geo-chronometrischen Gerùsts fur sent at that time. On the premise (perhaps bien supposer, pour une période donnée, que môgliche glaziale Ablagerungen im Sanga- false) that Laurentide Ice was in fact extensive les glaces ont entièrement envahi une région monium oder frùhen glazialen Wisconsin during the Early Wisconsinan, a map showing ou en étaient tout à fait absentes. En tenant fùhrte dazu, dap in den meisten Gebieten je maximum possible ice extent, as put forward pour acquis (?) que la calotte laurentidienne nach Interpretationsweise das Eis in jener by some authors is presented and the gla­ était en fait très étendue au Wisconsinien Zeit entweder vollstândig ùberflutete oder gar cigenic units possibly recording the ice inférieur, on présente une carte montrant son nicht vorhanden war. Ausgehend von der advance are shown in a correlation chart. étendue maximale et un tableau de corrélation (vielleicht falschen) Prâmisse, dap sich das This post Sangamonian sensu stricto entre les unités glaciaires. Les glaciers pos­ laurentische Eis tatsâchlich wàhrend des frù­ (substage 5e) -pre Middle Wisconsinan limit térieurs au Sangamonien sensu stricto (sous- hen glazialen Wisconsin ausdehnte, wird eine of ice extent is generally more extensive than phase 5e) et antérieurs au Wisconsinien Karte mit der môglichen maximalen Eisaus- the Late Wisconsinan (stage 2) limit. The ge­ moyen sont généralement plus étendues dehnung gezeigt, entsprechend der Annahme ometry of the ice sheet margin and scanty qu'au Wisconsinien supérieur (phase 2). La einiger Autoren; und in einer dazu in Verbin- available information on direction of ice géométrie de la marge glaciaire et les dung stehenden Ùbersicht werden die gla­ movements indicate that this assumed Early quelques données sur la direction de l'écou­ zialen Einheiten gezeigt, die den vermutlichen Wisconsinan ice likely developed in a very lement montrent que les inlandsis du Wis­ Eisvorstop dokumentieren. Dièse Grenze der similar manner to that of the Late Wisconsinan consinien inférieur et du Wisconsinien Eisausdehnung im Postsangamonium sensu ice complex. A hypothetical growth model of supérieur se sont développés de façon si­ stricto (Unterphase 5e) vor dem mittleren the Laurentide Ice Sheet, following the last milaire. On présente enfin un modèle hy­ glazialen Wisconsin ist im Allgemeinen aus- interglaciation is also proposed. pothétique de croissance de la calotte gedehnter als die Grenze im spâten glazialen laurentidienne après le dernier interglaciaire. Wisconsin (Phase 2). Die Géométrie des Eisdeckenrands und ungenùgende zugân- gliche Informationen ùber die Richtung der Eisbewegungen zeigen, dap dieses vermu­ tlich aus dem frùhen glazialen Wisconsin stammende Eis môglicherweise sich àhnlich entwickelte wie die Eisdecke des spâten gla­ zialen Wisconsin. Auperdem wird ein hy- pothetisches Wachstumsmodell der laurentischen Eisdecke nach der letzten In- terglazialzeit vorgestellt. * Geological Survey of Canada Contribution 33186 200 J.-S. VINCENT and V. K. PREST INTRODUCTION for one view point at the expense of another. The documents only serve to illustrate a view point. The location of sites The continental evidence for the beginning of the Laurentide mentioned in the text is shown on Figure 1 and numbers in Ice Sheet1 sometime during the Sangamonian (marine oxygen brackets throughout the paper refer to this figure. isotope stage 5) or Early Wisconsinan (stage 4) and before the Middle Wisconsinan (stage 3) is the subject of this
Load more

Recommended publications
  • Vegetation and Fire at the Last Glacial Maximum in Tropical South America
    Past Climate Variability in South America and Surrounding Regions Developments in Paleoenvironmental Research VOLUME 14 Aims and Scope: Paleoenvironmental research continues to enjoy tremendous interest and progress in the scientific community. The overall aims and scope of the Developments in Paleoenvironmental Research book series is to capture this excitement and doc- ument these developments. Volumes related to any aspect of paleoenvironmental research, encompassing any time period, are within the scope of the series. For example, relevant topics include studies focused on terrestrial, peatland, lacustrine, riverine, estuarine, and marine systems, ice cores, cave deposits, palynology, iso- topes, geochemistry, sedimentology, paleontology, etc. Methodological and taxo- nomic volumes relevant to paleoenvironmental research are also encouraged. The series will include edited volumes on a particular subject, geographic region, or time period, conference and workshop proceedings, as well as monographs. Prospective authors and/or editors should consult the series editor for more details. The series editor also welcomes any comments or suggestions for future volumes. EDITOR AND BOARD OF ADVISORS Series Editor: John P. Smol, Queen’s University, Canada Advisory Board: Keith Alverson, Intergovernmental Oceanographic Commission (IOC), UNESCO, France H. John B. Birks, University of Bergen and Bjerknes Centre for Climate Research, Norway Raymond S. Bradley, University of Massachusetts, USA Glen M. MacDonald, University of California, USA For futher
    [Show full text]
  • WELLESLEY TRAILS Self-Guided Walk
    WELLESLEY TRAILS Self-Guided Walk The Wellesley Trails Committee’s guided walks scheduled for spring 2021 are canceled due to Covid-19 restrictions. But… we encourage you to take a self-guided walk in the woods without us! (Masked and socially distanced from others outside your group, of course) Geologic Features Look for geological features noted in many of our Self-Guided Trail Walks. Featured here is a large rock polished by the glacier at Devil’s Slide, an esker in the Town Forest (pictured), and a kettle hole and glacial erratic at Kelly Memorial Park. Devil’s Slide 0.15 miles, 15 minutes Location and Parking Park along the road at the Devil’s Slide trailhead across the road from 9 Greenwood Road. Directions From the Hills Post Office on Washington Street, turn onto Cliff Road and follow for 0.4 mile. Turn left onto Cushing Road and follow as it winds around for 0.15 mile. Turn left onto Greenwood Road, and immediately on your left is the trailhead in patch of woods. Walk Description Follow the path for about 100 yards to a large rock called the Devil’s Slide. Take the path to the left and climb around the back of the rock to get to the top of the slide. Children like to try out the slide, which is well worn with use, but only if it is dry and not wet or icy! Devil’s Slide is one of the oldest rocks in Wellesley, more than 600,000,000 years old and is a diorite intrusion into granite rock.
    [Show full text]
  • Stratigraphy and Correlation of Glacial Deposits of the Rocky Mountains, the Colorado Plateau and the Ranges of the Great Basin
    STRATIGRAPHY AND CORRELATION OF GLACIAL DEPOSITS OF THE ROCKY MOUNTAINS, THE COLORADO PLATEAU AND THE RANGES OF THE GREAT BASIN Gerald M. Richmond u.s. Geological Survey, Box 25046, Federal Center, MS 913, Denver, Colorado 80225, U.S.A. INTRODUCTION glaciations (Charts lA, 1B) see Fullerton and Rich- mond, Comparison of the marine oxygen isotope The Rocky Mountains, Colorado Plateau, and Basin record, the eustatic sea level record, and the chronology and Range Provinces (Fig. 1) together occupy much of of glaciation in the United States of America (this the western interior United States. These regions volume). include approximately 140 mountain ranges that were glaciated during the Pleistocene. Most of the glaciers Historical Perspective were valley glaciers, but ice caps formed on uplands Following early recognition of deposits of two alpine locally. Discussion of the deposits of all of these ranges glaciations (Gilbert, 1890; Ball, 1908; Capps, 1909; would require monographic analysis. To avoid this, Atwood, 1909), deposits of three glaciations gradually representative ranges in each province are reviewed. became widely recognized (Alden, 1912, 1932, 1953; Atwood and Mather, 1912, 1932; Alden and Stebinger, Purpose and Scope 1913; Blackwelder, 1915; Atwood, 1915; Fryxell, 1930; This report summarizes the evidence for correlation Bradley, 1936). Subsequently drift of the intermediate of the Quaternary glacial deposits in 26 broadly glaciation was shown to represent two glacial advances distributed mountain ranges selected on the basis of (Fryxell, 1930; Horberg, 1938; Richmond, 1948, 1962a; availability of detailed information and length of glacial Moss, 1951a; Nelson, 1954; Holmes and Moss, 1955), record. and the older drift was shown to include deposits of Because the glacial deposits rarely are traceable from three glaciations (Richmond, 1957, 1962a, 1964a).
    [Show full text]
  • Model by Keven
    High-quality constraints on the glacial isostatic adjustment process over North America: The ICE-7G_NA (VM7) model by Keven Roy A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Graduate Department of Physics University of Toronto © Copyright 2017 by Keven Roy Abstract High-quality constraints on the glacial isostatic adjustment process over North America: The ICE-7G_NA (VM7) model Keven Roy Doctor of Philosophy Graduate Department of Physics University of Toronto 2017 The Glacial Isostatic Adjustment (GIA) process describes the response of the Earth’s surface to variations in land ice cover. Models of the phenomenon, which is dominated by the influence of the Late Pleistocene cycle of glaciation and deglaciation, depend on two fundamental inputs: a history of ice-sheet loading and a model of the radial variation of mantle viscosity. Various geophysical observables enable us to test and refine these models. In this work, the impact of the GIA process on the rotational state of the planet will be analyzed, and new estimates of the long-term secular trend associated with the GIA process will be provided. It will be demonstrated that it has undertaken a significant change since the mid-1990s. Other important observables include the vast amount of geological inferences of past sea level change that exist for all the main coasts of the world. The U.S. Atlantic coast is a region of particular interest in this regard, due to the fact that data from the length of this coast provides a transect of the forebulge associated with the former Laurentide ice sheet.
    [Show full text]
  • During the Last Ice Age As Ice Sheets Moved Southward Over Our Region, Glaciers Broke Off and Carried Pieces of the Underlying Bedrocks
    “Glacial Erratics and Fieldstones” Boulders and other rocks broken off and carried by ice sheets covering this region were left in place when the glaciers melted. Geologists call these “erratics.”. Early settlers called them “fieldstones” and used them to build their house walls. During the last Ice Age as ice sheets moved southward over our region, glaciers broke off and carried pieces of the underlying bedrocks. When the ice melted, the fragments were left scattered over the surface. Geologists call such transported rocks “glacial erratics,” because they are different from the native bedrock. Most of these were pebble- and boulder-sized, mixed into sands and clay. A few are more than 10 feet high, such as Haring Rock in the Tenafly Nature Center (Fig 1A) and Tripod Rock in Sussex County (Fig. 1b). Fig. 2 shows images of erratics of various sized in a state park. As the ice sheets moved, rocks underneath often scratched parallel grooves in the bedrocks. These are called “glacial striations” (Fig. 3). Until Englewood Township was formally organized in 1859, most of what is now our City consisted of small farms which stretched from Overpeck Creek uphill to the Hudson River. Like other early European settlers, the farmers needed to move the boulders and other glacial erratics to create plowable fields. Rocks were gathered to build stone walls typical of New England and other glaciated parts of the Northeast. (Fig. 4). Many of the stones collected from the fields (“fieldstones”) were trimmed to make the walls of homes and other buildings. Many of the remaining buildings from the Dutch/English colonial period and the early 19th Century here in Englewood and vicinity incorporated “fieldstones” in their walls.
    [Show full text]
  • The History of Ice on Earth by Michael Marshall
    The history of ice on Earth By Michael Marshall Primitive humans, clad in animal skins, trekking across vast expanses of ice in a desperate search to find food. That’s the image that comes to mind when most of us think about an ice age. But in fact there have been many ice ages, most of them long before humans made their first appearance. And the familiar picture of an ice age is of a comparatively mild one: others were so severe that the entire Earth froze over, for tens or even hundreds of millions of years. In fact, the planet seems to have three main settings: “greenhouse”, when tropical temperatures extend to the polesand there are no ice sheets at all; “icehouse”, when there is some permanent ice, although its extent varies greatly; and “snowball”, in which the planet’s entire surface is frozen over. Why the ice periodically advances – and why it retreats again – is a mystery that glaciologists have only just started to unravel. Here’s our recap of all the back and forth they’re trying to explain. Snowball Earth 2.4 to 2.1 billion years ago The Huronian glaciation is the oldest ice age we know about. The Earth was just over 2 billion years old, and home only to unicellular life-forms. The early stages of the Huronian, from 2.4 to 2.3 billion years ago, seem to have been particularly severe, with the entire planet frozen over in the first “snowball Earth”. This may have been triggered by a 250-million-year lull in volcanic activity, which would have meant less carbon dioxide being pumped into the atmosphere, and a reduced greenhouse effect.
    [Show full text]
  • Late Pleistocene Glacial Equilibrium-Line Altitudes in the Colorado Front Range: a Comparison of Methods
    QUATERNARY RESEARCH l&289-310 (1982) Late Pleistocene Glacial Equilibrium-Line Altitudes in the Colorado Front Range: A Comparison of Methods THOMAS C. MEIERDING Department of Geography and Center For Climatic Research, University of Delaware, Newark, Delaware 19711 Received July 6, 1982 Six methods for approximating late Pleistocene (Pinedale) equilibrium-line altitudes (ELAs) are compared for rapidity of data collection and error (RMSE) from first-order trend surfaces, using the Colorado Front Range. Trend surfaces computed from rapidly applied techniques, such as glacia- tion threshold, median altitude of small reconstructed glaciers, and altitude of lowest cirque floors have relatively high RMSEs @I- 186 m) because they are subjectively derived and are based on small glaciers sensitive to microclimatic variability. Surfaces computed for accumulation-area ratios (AARs) and toe-to-headwall altitude ratios (THARs) of large reconstructed glaciers show that an AAR of 0.65 and a THAR of 0.40 have the lowest RMSEs (about 80 m) and provide the same mean ELA estimate (about 3160 m) as that of the more subjectively derived maximum altitudes of Pinedale lateral moraines (RMSE = 149 m). Second-order trend surfaces demonstrate low ELAs in the latitudinal center of the Front Range, perhaps due to higher winter accumulation there. The mountains do not presently reach the ELA for large glaciers, and small Front Range cirque glaciers are not comparable to small glaciers existing during Pinedale time. Therefore, Pleistocene ELA depression and consequent temperature depression cannot reliably be ascertained from the calcu- lated ELA surfaces. INTRODUCTION existed in alpine regions (Charlesworth, Glacial equilibrium-line altitudes (ELAs) 1957; ostrem, 1966; Flint, 1971; Andrews, have been widely used to infer present and 1975).
    [Show full text]
  • 13. Late Pliocene-Pleistocene Glaciation
    13. LATE PLIOCENE - PLEISTOCENE GLACIATION W. A. Berggren, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts The discussion in this chapter is broken down into two increase in the former exceeding that of the latter; or parts: the first deals with glaciation in the North Atlantic as (v) less detritals, clay and carbonate deposited per unit time revealed in the data obtained on Leg 12; in the second part (that is, decreased sedimentation rate) with the decrease in an attempt is made to provide a chronologic framework of the latter exceeding the former. In view of the demon- Late Pliocene-Pleistocene glaciation and to correlate gla- strable increase in sedimentation rate above the preglacial/ cial/interglacial sequences as recorded in land and deep-sea glacial boundary at Sites 111, 112 and 116 due to increased sediments. amounts of detrital minerals and the fact that glacial periods in high latitudes are characterized by a carbonate GLACIATION IN THE NORTH ATLANTIC minimum (Mclntyre et al., in press) it can be seen that the One of the most significant aspects of Leg 12 was the correct explanation for the increase in natural gamma activ- various results which were obtained regarding glaciation in ity in the glacial part of the section is rather complex. Thin the North Atlantic. Glacial sediments were encountered at bands of carbonate were found at various levels intercalated all sites in the North Atlantic with the exception of Site with detrital-rich clays which indicates interglacial intervals, 117 (for the purpose of this discussion the North Atlantic so that the correct explanation probably lies with (iii) encompasses Sites 111 through 117; Sites 118 and 119 are above.
    [Show full text]
  • Glaciers and Glaciation
    M18_TARB6927_09_SE_C18.QXD 1/16/07 4:41 PM Page 482 M18_TARB6927_09_SE_C18.QXD 1/16/07 4:41 PM Page 483 Glaciers and Glaciation CHAPTER 18 A small boat nears the seaward margin of an Antarctic glacier. (Photo by Sergio Pitamitz/ CORBIS) 483 M18_TARB6927_09_SE_C18.QXD 1/16/07 4:41 PM Page 484 limate has a strong influence on the nature and intensity of Earth’s external processes. This fact is dramatically illustrated in this chapter because the C existence and extent of glaciers is largely controlled by Earth’s changing climate. Like the running water and groundwater that were the focus of the preceding two chap- ters, glaciers represent a significant erosional process. These moving masses of ice are re- sponsible for creating many unique landforms and are part of an important link in the rock cycle in which the products of weathering are transported and deposited as sediment. Today glaciers cover nearly 10 percent of Earth’s land surface; however, in the recent ge- ologic past, ice sheets were three times more extensive, covering vast areas with ice thou- sands of meters thick. Many regions still bear the mark of these glaciers (Figure 18.1). The basic character of such diverse places as the Alps, Cape Cod, and Yosemite Valley was fashioned by now vanished masses of glacial ice. Moreover, Long Island, the Great Lakes, and the fiords of Norway and Alaska all owe their existence to glaciers. Glaciers, of course, are not just a phenomenon of the geologic past. As you will see, they are still sculpting and depositing debris in many regions today.
    [Show full text]
  • 65Th Annual Tri-State Geological Field Conference 2-3 October 2004
    65th Annual Tri-State Geological Field Conference 2-3 October 2004 Weis Earth Science Museum Menasha, Wisconsin The Lake & The Ledge Geological Links between the Niagara Escarpment and Lake Winnebago Joanne Kluessendorf & Donald G. Mikulic Organizers The Lake & The Ledge Geological Links between the Niagara Escarpment and Lake Winnebago 65th Annual Tri-State Geological Field Conference 2-3 October 2004 by Joanne Kluessendorf Weis Earth Science Museum, Menasha and Donald G. Mikulic Illinois State Geological Survey, Champaign With contributions by Bruce Brown, Wisconsin Geological & Natural History Survey, Stop 1 Tom Hooyer, Wisconsin Geological & Natural History Survey, Stops 2 & 5 William Mode, University of Wisconsin-Oshkosh, Stops 2 & 5 Maureen Muldoon, University of Wisconsin-Oshkosh, Stop 1 Weis Earth Science Museum University of Wisconsin-Fox Valley Menasha, Wisconsin WELCOME TO THE TH 65 ANNUAL TRI-STATE GEOLOGICAL FIELD CONFERENCE. The Tri-State Geological Field Conference was founded in 1933 as an informal geological field trip for professionals and students in Iowa, Illinois and Wisconsin. The first Tri-State examined the LaSalle Anticline in Illinois. Fifty-two geologists from the University of Chicago, University of Iowa, University of Illinois, Northwestern University, University of Wisconsin, Northern Illinois State Teachers College, Western Illinois Teachers College, and the Illinois State Geological Survey attended that trip (Anderson, 1980). The 1934 field conference was hosted by the University of Wisconsin and the 1935 by the University of Iowa, establishing the rotation between the three states. The 1947 Tri-State visited quarries at Hamilton Mound and High Cliff, two of the stops on this year’s field trip.
    [Show full text]
  • Geology, Utah State University, Logan, Utah Topography and Is Composed of Highly Resistant, Fractured Gabbroic Rock
    Using inherited cosmogenic 36Cl to constrain glacial erosion rates of the Cordilleran ice sheet Jason P. Briner* Terry W. Swanson Department of Geological Sciences and Quaternary Research Center, University of Washington, Box 351310, Seattle, Washington 98195 ABSTRACT Cosmogenic 36Cl/Cl ratios measured from glacially eroded bedrock provide the first quan- titative constraints on the magnitude, rate, and spatial distribution of glacial erosion over the last glacial cycle. Of 23 36Cl/Cl ratios, 8 yield exposure ages that predate the well-constrained deglaciation of the Puget Lowland, Washington, and are inferred to result from 36Cl inherited from prior exposure during the last interglaciation where ice did not erode enough rock (~1.80–2.95 m) to reset 36Cl/Cl ratios to background levels. Surfaces possessing inherited 36Cl evidently were abraded only 0.25–1.06 m, corresponding to abrasion rates of 0.09–0.35 mm˙yr –1. These results indicate that in the absence of glacial quarrying, the Cordilleran ice sheet may have abraded as little as 1–2 m of bedrock near its equilibrium-line altitude over the last glacial cycle, equating to only tens of meters over the entire Quaternary. INTRODUCTION Where independent age control constrains the timing of surface expo- Although many researchers have discussed the glacial origin of stoss- sure following a given geomorphic event, such as a glaciation, 36Cl concen- and-lee topography (e.g., Jahns, 1943; Hallet, 1979), only Jahns (1943) at- trations that are higher than expected can be inferred to reflect 36Cl inherited tempted to determine quantitative estimates of glacial erosion by using ex- from prior exposure, presumably attributable to a lack of sufficient glacial ero- foliation patterns in granitic domes that were differentially eroded by the sion to remove the surface rock in which 36Cl accumulated prior to glaciation.
    [Show full text]
  • Lower Devonian Glacial Erratics from High Mountain, Northern New Jersey, USA: Discovery, Provenance, and Significance
    Lower Devonian glacial erratics from High Mountain, northern New Jersey, USA: Discovery, provenance, and significance Martin A. Becker1*and Alex Bartholomew2 1. Department of Environmental Science, William Paterson University, Wayne, New Jersey 07470, USA 2. Geology Department, SUNY, New Paltz, New York 12561, USA *Corresponding author <[email protected]> Date received 31 January 2013 ¶ Date accepted 22 November 2013 ABSTRACT Large, fossiliferous, arenaceous limestone glacial erratics are widespread on High Mountain, Passaic County, New Jersey. Analysis of the invertebrate fossils along with the distinct lithology indicates that these erratics belong to the Rickard Hill Facies of the Schoharie Formation (Lower Devonian, Tristates Group). Outcrops of the Rickard Hill Facies of the Schoharie Formation occur in a narrow belt within the Helderberg Mountains Region of New York due north of High Mountain. Reconstruction of the glacial history across the Helderberg Mountains Region and New Jersey Piedmont indicates that the Rickard Hill Erratics were transported tens of kilometers from their original source region during the late Wisconsinan glaciation. The Rickard Hill Erratics provide a unique opportunity to reconstruct an additional element of the complex surficial geology of the New Jersey Piedmont and High Mountain. Palynology of kettle ponds adjacent to High Mountain along with cosmogenic-nuclide exposure studies on glacial erratics from the late Wisconsinan terminal moraine and the regional lake varve record indicate that the final deposition of the Rickard Hill Erratics occurred within a few thousand years after 18 500 YBP. RÉSUMÉ Les grand blocs erratiques fossilifères apparaissent disperses dans les formations basaltiques de Preakness (Jurassique Inférieur) sur le mont High, dans le conte de Passaïc, dans l’État du New Jersey (NJ).
    [Show full text]