Glaciation: A “Cool” Topic for Dynamic Planet 2019 DIVISION A COACHING GUIDE prepared by Science Olympiad and the TOKAY SCIENCE OLYMPIAD GLACIER TEAMS

The purpose of this guide is to help coaches in Division A in San Joaquin County prepare elementary students for the competition. It is not intended to be a sole source of the study material given to students but rather a guide to initiate the study of glaciers.

I. Definition of glaciers: areas of snow and ice that have accumulated over many years and have at some time flowed

II. Types of glaciers A. Mountain/ Alpine (or cirque): fill bowl-like depressions that may be a few square kilometers B. Valley glaciers: flow through valleys and may be enlarged by cirque glaciers C. Piedmont glaciers: valley glaciers that flow out of the valley and onto the adjacent plain D. Ice fields: massive collections of glaciers E. Ice sheets: largest accumulations of glaciers- Cordilleran and Laurentide. The Antarctic comprises 3 ice sheets: Antarctic Peninsula, West Antarctic Ice Sheet, and East Antarctic Ice Sheet F. Rock glaciers G. Ice shelves- areas of floating ice, margin of an ice sheet (slow) H. Ice stream- fast moving sections of ice sheet I. Tidewater –glaciers that terminate in the sea J. Temperate K. Cold glaciers L. Continental glaciers M. Ice tongues

III. Formation of glaciers A. Latitude B. Elevation: each 1000-foot change in elevation causes a 3 ̊ change in temperature C. Slant of rays from the sun: glaciers have a better chance of surviving on the sides facing away from the sun (windward and leeward) D. Prevailing wind direction: Snow is blown from the windward to the leeward sides of mountains. Prevailing westerlies in the U.S. blow from west to east.

IV. Glacial history A. When did glaciers advance from polar regions toward the equator? B. Quaternary Period: Past 1.6 million years 1. Pleistocene Epoch: from the beginning of the Quaternary Period to the end of the last glaciation 2. Holocene Epoch: 10,000 years ago to present C. Interglacial Periods: ~ 20,000 years in length according to ice core studies D. Snowball Earth E. Medieval Warming- Little Ice Age F. Luis Agassiz G. Cordilleran and Laurentide Glaciers

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V. Mechanisms responsible for formation and maintenance of glaciers: a change of ~ 6 ̊ below present world temperatures can mean a return to a glacial period

A. Solar variability: a change in the amount of energy produced by the sun 1. Maunder minimum B. Insolation: amount of the sun’s energy that strikes Earth’s surface -Milankovitch Cycle 1. Eccentricity. Earth’s orbital path shape around the sun 2. Obliquity. Variation in the tilt of Earth’s axis over a 41,000 year cycle 3. Precession. Wobble of Earth’s axis C. Dust 1. Particles from Earth’s surface carried into the atmosphere 2. Dust particles reflect incoming solar ultraviolet rays causing Earth’s surface to cool 3. Includes wind-eroded dust, volcanic particles (dust and gas), forest fires D. Gases that absorb heat and raise the temperature of the atmosphere –Natural and Anthropogenic 1. Water vapor 2. Carbon dioxide 3. Methane 4. Nitrous oxide 5. Ozone 6. CFCs E. Ocean current circulation: the North Atlantic Deep Water Current is one long, continuous ocean current that takes ~ 1000 years to complete (The Great Conveyor) F. Sea ice 1. Reflects incoming solar radiation 2. Blocks ocean water from sinking, thus preventing thermohaline circulation of ocean currents

VI. Crystal structure of ice A. Ice is a mineral 1. Definite crystal structure 2. Definite chemical composition 3. Naturally occurring 4. Inorganic 5. Solid (crystal) B. Crystal structure of a snowflake is a hexagonal molecule due to hydrogen bonding C. The cooler the temperature, the less delicate and the more blocky the snowflake D. As snow accumulates, the shape of each crystal begins to change as it is compressed, melted, and crystallized 1. Firn 2. Glacial Ice E. Density 1. Snowflakes ~ 0.1 g/cm3 2. Firn (German term for last year’s snow) ~ 0.6 g/cm3 3. Glacial ice ~ 0.9 g/cm3 4. Density of fresh water for comparison ~ 1.0 g/cm3

2 VII. Movement of glaciers A. Flow mechanisms 1. Slope of the bedrock surface: steepness of the land surface 2. Internal deformation: the ice crystals are flattened by the overlying pressure and lie parallel to the base of the glacier (like playing cards). Ice crystals slide along the platy flat surface of each successive ice crystal beneath them. 3. Basal meltwater and water that percolates downward from the surface to form a lubricating layer 4. Plasticity at 60 meter boundary B. Downwasting: when melting exceeds forward flow C. Types of movement 1. Compressional flow areas: where the glacier is constantly pushed from behind 2. Extensional flow areas: ice responds slowly to change and cannot flow fast enough to continually stay compressed. Ice pulls apart in the extensional flow areas to form crevasses. 3. Crevasses are formed because the surface ice cannot deform and therefore crack to accommodate the plastic flow of deeper ice. D. Most glaciers move ~ 0.5 meters per day. They may occasionally surge forward at speeds of 10’s or 100’s of meters per day. E. Glaciers never move backward, however, they may stall if the proper conditions for flow are not met. F. Gravity- most important force of glacial movement!!!!!

VIII. Parts of a glacier A. Head: uphill top end B. Terminus: downhill end C. : furthest forward movement of the glacier D. Snowline: area between summer melting and accumulation area where snow lasts from season to season E. Firn: year-old snow found in the accumulation area F. Superglacial streams: streams on the surface of glaciers that carry surface melt water G. Equilibrium Line Altitude (ELA): average position of the firn line. H. Superglacial debris: a large amount of dust and rocky material scattered over the surface of a glacier I. Moraine: piles of rock material that have eroded from the valley walls and pushed to the front and sides of a glacier J. Moulin: a hole or tunnel exposed on the glacial surface through which meltwater flows K. Proglacial lakes L. Crevasses M. Zone of accumulation N. Zone of ablation

IX. Sea Ice A. Definition: Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface Sea ice covers about 7% of the Earth’s surface and about 12% of the world’s oceans. Much of the world's sea ice is enclosed within the polar ice packs in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, including the ocean's ecosystems. Due to the action of winds, currents and temperature fluctuations, sea ice is very dynamic, leading to a wide variety of ice types and features. Sea ice may be contrasted with icebergs, which are chunks of ice shelves or glaciers that calve into the ocean. Depending on location, sea ice expanses may also incorporate icebergs. Source: Wikipedia B. Fast ice G. Deformation C. Drift ice 3 types of features: D. Pack ice 1. Rafted ice, one piece is overriding another; E. Classification based on age: new ice, nilas, young 2) Pressure ridges, a line of broken ice forced downward (to ice, first year, and old make up the keel) and upward (to make the sail); 3) Hummock, an hillock of broken ice that forms an uneven F. Driving forces surface. 3

X. Glacial geology: a study of the effect of glaciation on the landscape A. Erosional 1. Subglacial debris grinds against the bedrock abrading or eroding bits of rock 2. Subglacial material erodes striations or grooves up to a few centimeters deep and up to 10’s of meters long 3. Rock flour: glacial rocks grind into “flour” and are carried in streams 4. Frost wedging: when ice pushes from the sides and breaks off pieces of rock 5. Plucking: pieces of rock along joints or other features in the bedrock are wedged by frost and lifted or plucked from the surface 6. Horns: small cirque glaciers erode the tops of mountains and form horns (Matterhorn) 7. Erosional processes are responsible for creating classic “U” shaped valleys. Be able to distinguish between valleys made by glaciers and those made by rivers 8. Basal ice freezing 9. Roche mountonee (sheepback) 1. stoss 2. lee 10. Cirque 11. Arete 12. Col 13. Fjord 14. Glacial polish 15. Chattermarks 16. Striations

B. Depositional 1. Ice rafted debris: rock material carried away by ice and meltwater 2. Erratic: rocks transported through glacial actions and placed into areas of differing rock types 3. Kame terraces: debris deposited between glaciers and valley walls form conical, hilly deposits 4. Till: deposits formed underneath glaciers plastered down by moving ice as it drags debris across the land surface. 5. Eskers: superglacial material from the surface of a glacier carried through a moulin and into the glacier’s plumbing system forming long, snake-like (sinuous) ridges from the meltwater of a retreating glacier 6. Drumlins: material accumulates under a glacier, is covered with till, and then reshaped into an elongated ridge. These features indicate the relative direction of the flow of the glaciers at the time they were formed. 7. Moraines a. terminal (Outer Lands-, Martha’s Vineyard, , - USA and Giant’s Wall- Norway) b. end c. medial d. lateral e. ground

8. Glacial flour (rock flour) 9. Be able to tell what depositions are stratified and those that are not. Deposition by liquid water is stratified. C. Isostasy 1. Forebulge 2. Post Glacial Rebound (weight of glaciers pushes down on the crust, the ice melts, the weight is removed, the crust rebounds)

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XI. Glaciers in the hydrologic cycle A. Impacts 1. Climate 2. Streams 3. Lakes a. tarn b. kettle c. paternoster d. proglacial lakes e. glacial lake dam- Lake Missoula & Lake Agassiz & Lake Gimsvotn (Vatnajokull glacier) 1. coulee 2. scablands f. glacial milk lakes g. pluvial lakes 4. Oceans a. salinity (salt inclusions) b. brinicles –finger of death

5. Subglacial hydrology a. jokulhaups b. tuya

XII. Climate records.

A. Our present atmosphere contains all the same gases, soluble ions, and dusts as in earlier times but possibly in different concentrations B. Ice cores contain information about atmospheric conditions throughout the past 450,000 years Annual layers represent one year’s growth and are still distinguishable even after the layers have been compressed and transformed into glacial ice C. Sea level change: reallocation of water from the oceans to glaciers may cause a 300 foot drop in ocean waters – What are the ramifications to sea level drop? D. How current climate trends compare to the past E. Proxy data- what is it and how is it used F. Oxygen 18- Oxygen 16 ratio: how to read the data, where the data is found and what the data indicates in terms of climate record G. Ice core data H. Fossil evidence from ocean core samples

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