NOTES
Links to summaries of key issues for each topic
VISUALS
Links to images employed in lectures on a topic-by-topic basis
TEXT
Link to chapter outlines at online learning center at McGraw Hill.
NOTES
Links to summaries of key issues for each topic
|
Notes on Topic:
The notes represent summaries of key issues
for each topic
They emphasize the terminology used to describe
the various phenomena.
| 1. Measuring the Sea
Floor: |
| Learning Objectives: |
-
Approaches to studing the features of the sea floor
|
| Soundings: |
-
First taken using rope (later piano wire + cannonball), measured in fathoms.
echo soundings, reflection of sound pulse. Satellite altimetry: measures
undulations of sea surface related to bathymetry, an irregular surface
with basins, mountains, ridges, valleys etc.
|
| 2. Bathymetry of the Sea Floor |
| Learning Objectives: |
-
Topography and positions of ocean floor features
-
Shaping of the ocean floor by plate tectonics.
-
Features of spreading: ridges and fracture zones, abyssal plains.
-
Features of convergence: trenches and active continental margins
|
| Continental margins: |
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Active margins
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Seismic and narrow (e.g. US. west coast)
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Passive Margins
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aseismic and broad (e.g. US. east coast)
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three major parts and divider (break):
-
continental shelf (inner and outer),
-
shelf break - an abrupt change in slope,
-
continental slope, with steep gradient,
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continental rise (upper and lower).
-
sediments are trapped on shelf
-
behind a rock dam, seamount, island arc, salt dome or coral reef
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Submarine canyons slice continental margins
-
resemble submarine river valleys ('V'-shaped)
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act as channels for sediment transport to deep ocean
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often at mouths of major rivers (e.g. Hudson)
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exceptions: Monterey Canyon, similar in size to Grand Canyon
-
Turbidity currents:
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dense mixtures of water and sediment
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avalanches of mud and debris
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may be triggered by earthquakes (e.g. Grand Banks)
-
settles out slowly creating graded bedding
-
coarse-grained material at base, fining upward: turbidites
|
| Ocean basin floor: |
-
Abyssal plain (4 - 6 km deep)
-
covers >30% of Earth's surface
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abyssal hills (few '00 m) and seamounts.
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flat-topped seamounts or guyots
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sequence of formation:
-
volcanic islands, fringing reefs, barrier reefs and atolls
|
| Mid-ocean ridges, rises and trenches: |
-
Ridges rise above the ocean floor (~2km)
-
encircle the oceans
-
linked to lateral ridges and rises
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Trenches: narrow features (40 - 120km wide; 800 - 5,900km long)
-
most in Pacific
-
3 - 4km deeper than adjacent ocean floor
-
associated with island arcs and subduction
|
Department
of Geological Sciences,
1001
E. Tenth Street, Bloomington, IN 47405-1403
Phone:
(812) 855-5582 Last updated: 7 October 2000
Comments:
simon@indiana.edu
Copyright
2000, The Trustees of Indiana University
|
