DOCSLIB.ORG

Glaciers in Kansas Shane A

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Glaciers in Kansas Shane A Kansas Geological Survey Public Information Circular 28 • April 2009 Revised November 2020 Glaciers in Kansas Shane A. Lyle, Kansas Geological Survey Revised by Anthony L. Layzell, Kansas Geological Survey Introduction Yellowstone National Park area were During each stage, many smaller, Melting glaciers in Earth’s polar and deposited throughout the state. regional lobes of ice locally advanced alpine regions are beacons of climate During the Pleistocene, continent- and retreated (fig. 2). The Pre-Illinoian change. To better understand what sized ice sheets formed in different parts Stage included many glacial and is happening today, it is helpful to of the world: North America, Greenland, interglacial stages, with 11 distinct consider past glaciation and climate- Eurasia, Tibet, the Himalayas, and glacial stages currently recognized. The change examples. Glaciers seemingly Antarctica. Ice sheets in the polar regions Sangamonian was a warm interglacial couldn’t be further removed from the and Greenland were fairly stable, but stage of ice retreat. hot summers and windswept plains of other areas, including North America, At its peak, Pre-Illinoian ice covered Kansas. However, in the not-so-distant saw repeated expansion and contraction more than one-third of North America geologic past, glaciers repeatedly in response to fluctuating climates (fig. and extended into northeastern advanced across the Midwest and at 1). These successive glacial advances Kansas. In Kansas, at least two separate least twice reached northeast Kansas. As and retreats are known as glacial stages glacial advances took place, first from the ice progressed across the continent, and interglacial stages, respectively. Minnesota and later from the Dakota the landscape, climate, plants, and In North America, geologists regions. Ice lobes dammed the ancestral animals all changed. recognize four stages. They are the Pre- Kansas River in several places and The purpose of this public Illinoian (2.6 million–191,000 years ago), crept over the locations of present-day information circular is to show how Illinoian (191,000–130,000 years ago), Topeka, Lawrence, and downtown Kansas was literally on the forefront of Sangamonian (130,000–71,000 years Kansas City (fig. 2). climate change when a continental ice ago), and Wisconsinan (71,000–11,700 At its maximum, Illinoian ice covered sheet last extended into the northeast years ago). most of Illinois and did not enter corner of the state about 700,000 years ago. The geologic sciences are uniquely capable of describing these events, in that geologists nearly always look back in time to understand our current climate and environment. This publication provides insight into how the Midwest was affected by repeated continent-sized glacial advances during the Pleistocene Epoch. It explains glaciation in Kansas and the ecological and climate response since the last ice sheet retreat. The Pleistocene provides an important analog, or past example, to better understand some of the concepts associated with climate change. The Pleistocene The Pleistocene Epoch lasted from about 2.6 million to 11,700 years ago. Although commonly referred to as the Ice Age, the Pleistocene encompassed many glacial and interglacial events and warm and cool climates. It was also a period of volcanic activity in North America and along the North and South American Pacific coasts. In Kansas, at Figure 1. Extent of glaciation in North America. Solid white areas represent Late Wisconsinan ice least three large ash falls from volcanoes sheets and glaciers. Dotted white line indicates maximum extent of older Quaternary glaciations. in California, New Mexico, or the © 2013 Colorado Plateau Geosystems Inc. past Tarkio and Chillicothe, Missouri, Last glacial maximum ice limit into the present-day Missouri River Pre-Illinoian ice limit (fig. 2). The Big and Little Blue rivers in Unglaciated area Marshall and Pottawatomie counties probably developed as ice-margin streams or spillways to a proglacial lake, a lake formed just beyond the frontal margin of a glacier, near Atchison. Advancing ice also buried ancestral rivers that once flowed east through Marshall, Nemaha, Jackson, Brown, Atchison, and Doniphan counties in northeastern Kansas. Some of these valleys were more than 3 miles (4.8 km) wide, 400 feet (122 m) deep, and 75 miles (121 km) long. These buried valleys are now important groundwater sources for agriculture and industry in an area that otherwise does not have much groundwater. When the ice flow reached a depression such as the Kansas River, it spilled over the side, slowly filled the valley, then flowed over the opposite side. The ice was perhaps 300 feet (91 m) thick north of the river near Wamego and 500 feet (153 m) thick over the Kansas River valley. An ice lobe covering what is now the Kansas City area was Figure 2. Maximum extent of pre-Illinoian and late Pleistocene ice sheets (after “Glacial probably hundreds of feet thick (fig. 2). stratigraphy and paleomagnetism of late Cenozoic deposits of the north-central United States,” by Glacial ice transports all sizes of M. Roy, P. U. Clark, R. W. Barendregt, J. R. Glasmann, and R. J. Enkin, 2004, Geological Society sediment and rocks, often for hundreds of America Bulletin, v. 116, no. 1–2, https://doi.org/10.1130/B25325.1). of miles. Deposits of debris, ranging in size from boulders to clay particles, Kansas. Wisconsinan ice reached as Many geologists believe we haven’t left are collectively called glacial drift. Drift far south as Nebraska and Iowa, and the last ice age and simply consider the deposits are found in Washington, glacial deposits from this period provide Holocene as a short warm period before Marshall, Nemaha, Brown, Doniphan, important clues to the Pleistocene the next glacial onset. Riley, Pottawatomie, Jackson, Atchison, ecology and climate. Jefferson, Leavenworth, Wyandotte, The Wisconsinan Stage at the end Kansas Glacial Features Johnson, Douglas, Shawnee, and of the Pleistocene Epoch was followed The initial Kansas ice front was Wabaunsee counties. by the Holocene Epoch (11,700 years probably only tens of feet thick and Most glacial landforms, such as ago to the present). Although the slid irregularly forward under pressure moraines (mounds or ridges of drift Holocene has been a warm period from thicker ice to the north. Buried deposited by direct action of glacier without active glaciation, fluctuations wood in Atchison and Doniphan ice), are largely absent in Kansas due in the climate still have occurred. A counties indicates that the ice likely to long periods of erosion since pre- time of significant climatic variability overrode a spruce forest there. If a time- Illinoian time. Some glacial features and from about 900 to 1300 AD known as lapse picture could have recorded the deposits, however, are still visible on the the Medieval Warm Period (MWP) Pleistocene Epoch, it would have shown surface. Directional grooves carved into was first identified in northern Europe a lurching, amoeba-like ice movement limestone bedrock have been mapped in and later also documented elsewhere, along with ecological waves of tundra, Nemaha, Brown, Doniphan, Atchison, including parts of the western United forests, and grasslands progressing Jefferson, Leavenworth, Wyandotte, States. A shift to droughts of shorter across the Great Plains as glaciers Johnson, and Shawnee counties. A thick duration around 1500 coincided with advanced and retreated. blanket of mixed soil and rocks, called the onset of cooler climatic conditions Advancing ice reshaped the land, till, covers large portions of northeastern during a period known as the Little Ice forcing new stream channels and burying Kansas. “Till” is Scottish for a drift Age, which contributed to widespread others. Before glaciation, the ancestral deposit that formed underneath glacial social unrest in Europe. In France, crop Missouri River was a lesser tributary to ice and was not reworked by meltwater failure due to climatic changes helped a larger ancestral Kansas River. Then (water from melting snow or ice that spark the French Revolution that led advancing ice pushed the drainage from flows out in streams and carries rocks to the beheading of Marie Antoinette. a now-buried river valley that flowed and sediment away from a glacier). 2 Figure 3. Sea of Sioux Quartzite erratics on ridge crest 5 miles (8 km) south of Wamego. Glacial ice carried and dropped Monument in southern Minnesota, was previously weathered rocks from carried almost 345 miles (552 km) into hundreds of miles away into Kansas. Kansas. Collectively called erratics, these Because glacial retreat exposed lake rock fragments range from the size beds and meltwater left river valleys of pebbles to house-sized blocks. The covered with silt-sized sediment, large most common is Sioux Quartzite, tracts of land were susceptible to wind a pink metamorphosed sandstone erosion. Strong prevailing winds picked more than a billion years old. Sioux up lightweight debris and whipped up Indiana Quartzite boulders in Kansas came from immense sand and sediment storms southern Minnesota, South Dakota, that far exceeded the storms of the Dust and northwestern Iowa. Sometimes Bowl era. These storms blanketed the these rocks occur in such density Midwest with sand dunes and thick that geologists describe the resulting layers of fine-grained silt called loess, block field or masses of rock rubble on which is still found at or near the surface summits as a felsenmeer, German for throughout much of Kansas (fig. 5). Figure 4. Sources of identifiable glacial erratics “sea of rocks” (fig. 3). Before disappearing from northeast found in northeastern Kansas. Fragments of More exotic erratics, such as granitic Kansas, pre-Illinoian ice thinned, Sioux Quartzite are common throughout the rocks, Lake Superior agate, Duluth-area leaving hilltops exposed like islands terminal zone and eastward into Missouri. iron ore, Keweenawan volcanics, and in a sea of ice. In valleys, stagnant and Specimens of ore from the Iron Ranges are native copper, are occasionally found in isolated ice persisted for centuries before scarce.
Load more

Recommended publications
  • Wisconsinan and Sangamonian Type Sections of Central Illinois
    557 IL6gu Buidebook 21 COPY no. 21 OFFICE Wisconsinan and Sangamonian type sections of central Illinois E. Donald McKay Ninth Biennial Meeting, American Quaternary Association University of Illinois at Urbana-Champaign, May 31 -June 6, 1986 Sponsored by the Illinois State Geological and Water Surveys, the Illinois State Museum, and the University of Illinois Departments of Geology, Geography, and Anthropology Wisconsinan and Sangamonian type sections of central Illinois Leaders E. Donald McKay Illinois State Geological Survey, Champaign, Illinois Alan D. Ham Dickson Mounds Museum, Lewistown, Illinois Contributors Leon R. Follmer Illinois State Geological Survey, Champaign, Illinois Francis F. King James E. King Illinois State Museum, Springfield, Illinois Alan V. Morgan Anne Morgan University of Waterloo, Waterloo, Ontario, Canada American Quaternary Association Ninth Biennial Meeting, May 31 -June 6, 1986 Urbana-Champaign, Illinois ISGS Guidebook 21 Reprinted 1990 ILLINOIS STATE GEOLOGICAL SURVEY Morris W Leighton, Chief 615 East Peabody Drive Champaign, Illinois 61820 Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/wisconsinansanga21mcka Contents Introduction 1 Stopl The Farm Creek Section: A Notable Pleistocene Section 7 E. Donald McKay and Leon R. Follmer Stop 2 The Dickson Mounds Museum 25 Alan D. Ham Stop 3 Athens Quarry Sections: Type Locality of the Sangamon Soil 27 Leon R. Follmer, E. Donald McKay, James E. King and Francis B. King References 41 Appendix 1. Comparison of the Complete Soil Profile and a Weathering Profile 45 in a Rock (from Follmer, 1984) Appendix 2. A Preliminary Note on Fossil Insect Faunas from Central Illinois 46 Alan V.
    [Show full text]
  • The Last Maximum Ice Extent and Subsequent Deglaciation of the Pyrenees: an Overview of Recent Research
    Cuadernos de Investigación Geográfica 2015 Nº 41 (2) pp. 359-387 ISSN 0211-6820 DOI: 10.18172/cig.2708 © Universidad de La Rioja THE LAST MAXIMUM ICE EXTENT AND SUBSEQUENT DEGLACIATION OF THE PYRENEES: AN OVERVIEW OF RECENT RESEARCH M. DELMAS Université de Perpignan-Via Domitia, UMR 7194 CNRS, Histoire Naturelle de l’Homme Préhistorique, 52 avenue Paul Alduy 66860 Perpignan, France. ABSTRACT. This paper reviews data currently available on the glacial fluctuations that occurred in the Pyrenees between the Würmian Maximum Ice Extent (MIE) and the beginning of the Holocene. It puts the studies published since the end of the 19th century in a historical perspective and focuses on how the methods of investigation used by successive generations of authors led them to paleogeographic and chronologic conclusions that for a time were antagonistic and later became complementary. The inventory and mapping of the ice-marginal deposits has allowed several glacial stades to be identified, and the successive ice boundaries to be outlined. Meanwhile, the weathering grade of moraines and glaciofluvial deposits has allowed Würmian glacial deposits to be distinguished from pre-Würmian ones, and has thus allowed the Würmian Maximum Ice Extent (MIE) –i.e. the starting point of the last deglaciation– to be clearly located. During the 1980s, 14C dating of glaciolacustrine sequences began to indirectly document the timing of the glacial stades responsible for the adjacent frontal or lateral moraines. Over the last decade, in situ-produced cosmogenic nuclides (10Be and 36Cl) have been documenting the deglaciation process more directly because the data are obtained from glacial landforms or deposits such as boulders embedded in frontal or lateral moraines, or ice- polished rock surfaces.
    [Show full text]
  • Lexicon of Pleistocene Stratigraphic Units of Wisconsin
    Lexicon of Pleistocene Stratigraphic Units of Wisconsin ON ATI RM FO K CREE MILLER 0 20 40 mi Douglas Member 0 50 km Lake ? Crab Member EDITORS C O Kent M. Syverson P P Florence Member E R Lee Clayton F Wildcat A Lake ? L L Member Nashville Member John W. Attig M S r ik be a F m n O r e R e TRADE RIVER M a M A T b David M. Mickelson e I O N FM k Pokegama m a e L r Creek Mbr M n e M b f a e f lv m m i Sy e l M Prairie b C e in Farm r r sk er e o emb lv P Member M i S ill S L rr L e A M Middle F Edgar ER M Inlet HOLY HILL V F Mbr RI Member FM Bakerville MARATHON Liberty Grove M Member FM F r Member e E b m E e PIERCE N M Two Rivers Member FM Keene U re PIERCE A o nm Hersey Member W le FM G Member E Branch River Member Kinnickinnic K H HOLY HILL Member r B Chilton e FM O Kirby Lake b IG Mbr Boundaries Member m L F e L M A Y Formation T s S F r M e H d l Member H a I o V r L i c Explanation o L n M Area of sediment deposited F e m during last part of Wisconsin O b er Glaciation, between about R 35,000 and 11,000 years M A Ozaukee before present.
    [Show full text]
  • 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]
  • Introduction to Geological Process in Illinois Glacial
    INTRODUCTION TO GEOLOGICAL PROCESS IN ILLINOIS GLACIAL PROCESSES AND LANDSCAPES GLACIERS A glacier is a flowing mass of ice. This simple definition covers many possibilities. Glaciers are large, but they can range in size from continent covering (like that occupying Antarctica) to barely covering the head of a mountain valley (like those found in the Grand Tetons and Glacier National Park). No glaciers are found in Illinois; however, they had a profound effect shaping our landscape. More on glaciers: http://www.physicalgeography.net/fundamentals/10ad.html Formation and Movement of Glacial Ice When placed under the appropriate conditions of pressure and temperature, ice will flow. In a glacier, this occurs when the ice is at least 20-50 meters (60 to 150 feet) thick. The buildup results from the accumulation of snow over the course of many years and requires that at least some of each winter’s snowfall does not melt over the following summer. The portion of the glacier where there is a net accumulation of ice and snow from year to year is called the zone of accumulation. The normal rate of glacial movement is a few feet per day, although some glaciers can surge at tens of feet per day. The ice moves by flowing and basal slip. Flow occurs through “plastic deformation” in which the solid ice deforms without melting or breaking. Plastic deformation is much like the slow flow of Silly Putty and can only occur when the ice is under pressure from above. The accumulation of meltwater underneath the glacier can act as a lubricant which allows the ice to slide on its base.
    [Show full text]
  • Sea Level and Global Ice Volumes from the Last Glacial Maximum to the Holocene
    Sea level and global ice volumes from the Last Glacial Maximum to the Holocene Kurt Lambecka,b,1, Hélène Roubya,b, Anthony Purcella, Yiying Sunc, and Malcolm Sambridgea aResearch School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia; bLaboratoire de Géologie de l’École Normale Supérieure, UMR 8538 du CNRS, 75231 Paris, France; and cDepartment of Earth Sciences, University of Hong Kong, Hong Kong, China This contribution is part of the special series of Inaugural Articles by members of the National Academy of Sciences elected in 2009. Contributed by Kurt Lambeck, September 12, 2014 (sent for review July 1, 2014; reviewed by Edouard Bard, Jerry X. Mitrovica, and Peter U. Clark) The major cause of sea-level change during ice ages is the exchange for the Holocene for which the direct measures of past sea level are of water between ice and ocean and the planet’s dynamic response relatively abundant, for example, exhibit differences both in phase to the changing surface load. Inversion of ∼1,000 observations for and in noise characteristics between the two data [compare, for the past 35,000 y from localities far from former ice margins has example, the Holocene parts of oxygen isotope records from the provided new constraints on the fluctuation of ice volume in this Pacific (9) and from two Red Sea cores (10)]. interval. Key results are: (i) a rapid final fall in global sea level of Past sea level is measured with respect to its present position ∼40 m in <2,000 y at the onset of the glacial maximum ∼30,000 y and contains information on both land movement and changes in before present (30 ka BP); (ii) a slow fall to −134 m from 29 to 21 ka ocean volume.
    [Show full text]
  • The Cordilleran Ice Sheet 3 4 Derek B
    1 2 The cordilleran ice sheet 3 4 Derek B. Booth1, Kathy Goetz Troost1, John J. Clague2 and Richard B. Waitt3 5 6 1 Departments of Civil & Environmental Engineering and Earth & Space Sciences, University of Washington, 7 Box 352700, Seattle, WA 98195, USA (206)543-7923 Fax (206)685-3836. 8 2 Department of Earth Sciences, Simon Fraser University, Burnaby, British Columbia, Canada 9 3 U.S. Geological Survey, Cascade Volcano Observatory, Vancouver, WA, USA 10 11 12 Introduction techniques yield crude but consistent chronologies of local 13 and regional sequences of alternating glacial and nonglacial 14 The Cordilleran ice sheet, the smaller of two great continental deposits. These dates secure correlations of many widely 15 ice sheets that covered North America during Quaternary scattered exposures of lithologically similar deposits and 16 glacial periods, extended from the mountains of coastal south show clear differences among others. 17 and southeast Alaska, along the Coast Mountains of British Besides improvements in geochronology and paleoenvi- 18 Columbia, and into northern Washington and northwestern ronmental reconstruction (i.e. glacial geology), glaciology 19 Montana (Fig. 1). To the west its extent would have been provides quantitative tools for reconstructing and analyzing 20 limited by declining topography and the Pacific Ocean; to the any ice sheet with geologic data to constrain its physical form 21 east, it likely coalesced at times with the western margin of and history. Parts of the Cordilleran ice sheet, especially 22 the Laurentide ice sheet to form a continuous ice sheet over its southwestern margin during the last glaciation, are well 23 4,000 km wide.
    [Show full text]
  • The Climate of the Last Glacial Maximum: Results from a Coupled Atmosphere-Ocean General Circulation Model Andrew B
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 104, NO. D20, PAGES 24,509–24,525, OCTOBER 27, 1999 The climate of the Last Glacial Maximum: Results from a coupled atmosphere-ocean general circulation model Andrew B. G. Bush Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Canada S. George H. Philander Program in Atmospheric and Oceanic Sciences, Department of Geosciences, Princeton University Princeton, New Jersey Abstract. Results from a coupled atmosphere-ocean general circulation model simulation of the Last Glacial Maximum reveal annual mean continental cooling between 4Њ and 7ЊC over tropical landmasses, up to 26Њ of cooling over the Laurentide ice sheet, and a global mean temperature depression of 4.3ЊC. The simulation incorporates glacial ice sheets, glacial land surface, reduced sea level, 21 ka orbital parameters, and decreased atmospheric CO2. Glacial winds, in addition to exhibiting anticyclonic circulations over the ice sheets themselves, show a strong cyclonic circulation over the northwest Atlantic basin, enhanced easterly flow over the tropical Pacific, and enhanced westerly flow over the Indian Ocean. Changes in equatorial winds are congruous with a westward shift in tropical convection, which leaves the western Pacific much drier than today but the Indonesian archipelago much wetter. Global mean specific humidity in the glacial climate is 10% less than today. Stronger Pacific easterlies increase the tilt of the tropical thermocline, increase the speed of the Equatorial Undercurrent, and increase the westward extent of the cold tongue, thereby depressing glacial sea surface temperatures in the western tropical Pacific by ϳ5Њ–6ЊC. 1. Introduction and Broccoli, 1985a, b; Broccoli and Manabe, 1987; Broccoli and Marciniak, 1996].
    [Show full text]
  • Glacial Geology of the Vandalia, Illinois, Region
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE i42 ILLINOtS GEOLOGICAL provided by Illinois Digital Environment for Access to Learning and Scholarship... S SURVEY LIBRARY 14.GS: CIR442 STATE ILLINOIS c. 1 OF DEPARTMENT OF REGISTRATION AND EDUCATION GLACIAL GEOLOGY OF THE VANDALIA. ILLINOIS. REGION Alan M. Jacobs Jerry A. Lineback CIRCULAR 442 1969 ILLINOIS STATE GEOLOGICAL SURVEY URBANA, ILLINOIS 61801 John C. Frye, Chief Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/glacialgeologyof442jaco GLACIAL GEOLOGY OF THE VANDALIA, ILLINOIS, REGION Alan M. Jacobs and Jerry A. Lineback ABSTRACT Deposits and soils of the Kansan, Yarmouthian, Illinoian, Sangamonian, and Wisconsinan Stages are pre- sent in the region surrounding Vandalia (south-central), Illinois. Kansan till exposures, with a truncated Yarmouth Soil, are exposed at a few places. The unaltered till is sandy and silty M and its less than 2-micron size fraction contains abundant illite and more calcite than dolomite. The Smithboro till (lowermost Illinoian) is relatively silty, plastic, and its less than 2-micron size fraction contains more dolomite than calcite and more expandable clay min- erals than any till in this region. The overlying Vandalia till (Illinoian) is relatively sandy, friable, and its less than 2-micron size fraction contains abundant illite and more dolomite than calcite. The Mulberry Grove silt lies between the Vandalia and Smithboro tills at some localities. The Hagarstown beds (Illinoian) overlie the Vandalia till and consist of sand, gravel, poorly sorted gravel, and gravelly till.
    [Show full text]
  • Stratigraphy and Pollen Analysis of Yarmouthian Interglacial Deposits
    22G FRANK R. ETTENSOHN Vol. 74 STRATIGRAPHY AND POLLEN ANALYSIS OP YARMOUTHIAN INTERGLACIAL DEPOSITS IN SOUTHEASTERN INDIANA1 RONALD O. KAPP AND ANSEL M. GOODING Alma College, Alma, Michigan 48801, and Dept. of Geology, Earlham College, Richmond, Indiana 47374 ABSTRACT Additional stratigraphic study and pollen analysis of organic units of pre-Illinoian drift in the Handley and Townsend Farms Pleistocene sections in southeastern Indiana have provided new data that change previous interpretations and add details to the his- tory recorded in these sections. Of particular importance is the discovery in the Handley Farm section of pollen of deciduous trees in lake clays beneath Yarmouthian colluvium, indicating that the lake clay unit is also Yarmouthian. The pollen diagram spans a sub- stantial part of Yarmouthian interglacial time, with evidence of early temperate and late temperate vegetational phases. It is the only modern pollen record in North America for this interglacial age. The pollen sequence is characterized by extraordinarily high per- centages of Ostrya-Carpinus pollen, along with Quercus, Pinus, and Corylus at the beginning of the record; this is followed by higher proportions of Fagus, Carya, and Ulmus pollen. The sequence, while distinctive from other North American pollen records, bears recogniz- able similarities to Sangamonian interglacial and postglacial pollen diagrams in the southern Great Lakes region. Manuscript received July 10, 1973 (73-50). THE OHIO JOURNAL OF SCIENCE 74(4): 226, July, 1974 No. 4 YARMOUTH JAN INTERGLACIAL DEPOSITS 227 The Kansan glaeiation in southeastern Indiana as discussed by Gooding (1966) was based on interpretations of stratigraphy in three exposures of pre-Illinoian drift (Osgood, Handley, and Townsend sections; fig.
    [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]
  • Routing of Meltwater from the Laurentide Ice Sheet During The
    LETTERS TO NATURE very high sulphate concentrations (Fig. 1). Thus, differences in P release has yet to prove the mechanism behind this relation­ P cycling between fresh waters and salt waters may also influence ship. If sediment P release were controlled largely by sulphur, the switch in nutrient limitation. our view of the lakes that are being affected by atmospheric A further implication of our findings is a possible effect of S pollution could be altered. It is believed generally that anthropogenic S pollution on P cycling in lakes. Our data lakes with well-buffered watersheds are insensitive to the effects indicate that aquatic systems with low sulphate concentrations of atmospheric S pollution. However, because changing have low RPR under either oxic or anoxic conditions; systems atmospheric S inputs can alter the sulfate concentration in with only slightly elevated sulphate concentrations have sig­ surface waters22 independent of acid neutralization in the water­ nificantly elevated RPR, particularly under anoxic conditions shed, the P cycle of even so-called 'insensitive' lakes may be (Fig. 1). Work on the relationship between sulphate loading and affected. D Received 22 February; accepted 15 August 1987. 17. Nurnberg. G. Can. 1 Fish. aquat. Sci. 43, 574-560 (1985). 18. Curtis, P. J. Nature 337, 156-156 (1989). 1. Bostrom, B .. Jansson. M. & Forsberg, G. Arch. Hydrobiol. Beih. Ergebn. Limno/. 18, 5-59 (1982). 19. Carignan, R. & Tessier, A. Geochim. cosmochim. Acta 52, 1179-1188 (1988). 2. Mortimer. C. H. 1 Ecol. 29, 280-329 (1941). 20. Howarth, R. W. & Cole, J. J. Science 229, 653-655 (1985).
    [Show full text]