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UNDERC INTRODUCTION #1: A REGION SHAPED BY GLACIERS

UNDERC INTRODUCTION #1: A REGION SHAPED BY GLACIERS. MULTIPLE PERIODS OF GLACIATION. PLEISTOCENE: 2 million years ago – 10,000 years ago 4 major glaciations in North America (~ 14 advances and retreats in last 1 million years)

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UNDERC INTRODUCTION #1: A REGION SHAPED BY GLACIERS

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  1. UNDERC INTRODUCTION #1:A REGION SHAPED BYGLACIERS

  2. MULTIPLE PERIODS OFGLACIATION PLEISTOCENE: 2 million years ago – 10,000 years ago 4 major glaciations in North America (~ 14 advances and retreats in last 1 million years) (However, probably continental glaciations for the past 10 million years)

  3. WHAT CAUSES GLACIATION? • Snows did not melt in northern regions during summer • 4 – 7oC decline in mean annual temperature (change in δ18O) Pleistocene Laurentide

  4. WHAT CAUSES GLACIATION? • Sea-level fluctuates as water forms glaciers • Gravitational effects of planetary bodies perturb Earth’s orbit which varies distribution of solar radiation (Milankovitch Cycles)

  5. MOST RECENT GLACIAL EXTENT

  6. Extent of Continental Glaciation • Anchorage • Juneau • Churchill Calgary Quebec • Seattle • Winnipeg Ottawa New York St. Paul Cleveland Chicago • San Francisco • Denver St. Louis

  7. GLACIAL ADVANCE AND RETREAT(Wisconsin Glaciation – Laurentide

  8. Glacier Cross Section New snow Ice crystals Compressed crystals Flowing crystals

  9. Inland Lakes Resultingfrom Melt Water • Anchorage • Juneau • Churchill Quebec Calgary Ottawa • Seattle • Winnipeg New York St. Paul Cleveland Chicago • San Francisco • Denver St. Louis Miami

  10. Formation of Kettle lakes Ice margin Ice blocks in outwash plain Continental Glacier Kettle lake at ice contact on terminal moraine Lake in irregular ground moraine Kettle lakes in outwash plain Kettle in drift Ice Lake

  11. Formation of Permafrost Lakes Permafrost No Permafrost

  12. Arctic Permafrost Lakes(Tundra, Northwest Territories, Canada)

  13. Land O’ Lakes Aquatic HabitatsAre Glacial Products • 35 lakes and bogs • 2 streams • many forest and wetland habitats Bergner Bay Long

  14. TERRESTRIAL REMNANTS • Glacial drift (deposits of earth and rock) till = ice-laid outwash = water-laid • Moraines (till deposited in ridges)

  15. ERRATICS: STRIATIONS: TERRESTRIAL REMNANTS

  16. TERRESTRIAL REMNANTS ESKER – subglacial streams that deposited gravel to now appear as a low winding ridge.

  17. GLACIAL ENVIRONMENTS

  18. HOW ARE ENVIRONMENTS RECONSTRUCTED?

  19. TODAY’S ENVIRONMENT

  20. HOW DID THINGS CHANGE? Pollen Viewer

  21. Mix Of Different Tree Species Since Glaciation

  22. Disequilibrium View of Forests Since Glaciation

  23. Dissimilarity in Tree Composition and Climate

  24. CHANGE CONTINUES • EVOLUTIONARY AND GEOLOGICAL CHANGE (inherent) • ECOLOGY OF AQUATIC HABITATS (inherent) • ECOLOGY OF TERRESTRIAL HABITATS (inherent) • HISTORICAL CHANGES WITH HUMANS (Native Americans and Europeans) – environmental history

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