Lecture 26 glaciers

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Chapter 12: Glaciers & glaciation

Chapter 12: Glaciers & glaciation

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What is a glacier?Glaciers are: Thick deposits of snow and ice. Form on land. Flow downhill by gravity by gravity. Basic types:• Alpine, or mountain

• Piedmont (small ice caps)

• Continental ice caps

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Fig 22.01 b

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Fig 22.04 a

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Fig 22.05 b

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Fig 22.04 c

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Fig 22.06

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Fig 22.11 c

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Fig 22.11 b

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Fig 22.08 c

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Fig 22.10 b

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Velocity of ice flow is highest in the center

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Fig 22.01 b Stephen Marshak Announcements:Final Exam is Wednesday, May 14 at 2:40PM in this room

Bring your student ID and a pencil!

Papers are due by 5PM tomorrow

Turn in a hard copy of paper to the front desk of the Geological Sciences Dept (6th floor of this building) and ask

that they time stamp it and place it in my mailbox

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Fig 22.08 b

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How a glacier moves: Internal flow.

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Fig 22.08 a

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How a glacier moves…basal slip.

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Fig 22.10 a

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Glacier formation/movement

 Glacier “budget”

 Snowline

 Zone of wastage

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Fig 22.13 a

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Whether a glacier is advancing or retreating dependson the balance between accumulation at the head

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Fig 22.13 b

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Fig 22.13 c

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….23 years later

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Fig 22.12

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Fig 22.15 b

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Fig 22.15 d

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Fig 22.15 a

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Glacial erosion

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Glacial erosion

2 ways: Plucking - Plucking glacier loosens/lifts/incorporates fractured rock

Abrasion - Glacier+rock fragments scrape over bedrock (like sandpaper), make rock flour

glacial striations

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Fig 22.17 d

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Fig 22.17 c

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Fig 22.18 a

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Fig 22.18 b

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Fig 22.18 c

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Glacially-eroded landforms

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Fig 22.20

Stephen Marshak

Fjords: Drowned glacial

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Fig 22.17 b

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Glacially-eroded landforms

Bridalveil FallsYosemite, CA