Sunday, September 04, 2005

Email Address and island chains

Hi people,

I would be glad to receive your email addresses (especially those with blogger accounts) so that I can invite you to be co-owners of the page (so that you can create new posts instead of just responding to old ones).

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re the question "using diagrams, explain how island chains can result from 'hot spot' activities" from (whoever you are :P pleease tell us your name lah)

What are the key terms to be defined?
1) island chains
chains of islands formed as a result of volcanoes emerging through the crustal plate from a hot spot plume, and then becoming extinct as the plate moves relatively from the plume (which has a fixed location), such that new areas of the plate (adjacent to the earlier volcano) lie over the plume and are eventually penetrated by hot rising magma to form new volcanoes.

This progression results in a chain of volcanic islands. Examples of island chain in the Pacific plate:
Kauai (oldest), Oahu, Maui, Hawaii(youngest)

2) hot spot activities
Relatively small, long-lasting, and exceptionally hot regions -- called hotspots -- that existed below the plates provide localized sources of high heat energy (thermal plumes) to sustain volcanism.
Specifically, Wilson hypothesized that the distinctive linear shape of the Hawaiian Island-Emperor Seamounts chain resulted from the Pacific Plate moving over a deep, stationary hotspot in the mantle, located beneath the present-day position of the Island of Hawaii.
-Heat from this hotspot produced a persistent source of magma by partly melting the overriding Pacific Plate.
-The magma, which is lighter than the surrounding solid rock, then rises through the mantle and crust to erupt onto the seafloor, forming an active seamount.
-Over time, countless eruptions cause the seamount to grow until it finally emerges above sea level to form an island volcano.
(source: http://pubs.usgs.gov/publications/text/hotspots.html)


Some references for you to practice your drawings of island chains related to hotspots:

http://volcano.und.nodak.edu/vwdocs/vwlessons/hot_spot_pics/Matt's_Island_Diagram.gif

3 Comments:

Anonymous Anonymous said...

thanks mr toh.. nurul here.. anyway, is that ans sufficient for a 12 marks qns?

7:42 PM

 
Blogger Daviddd said...

so thats a 12 mark question?
hmm think about it; are there 12 seperate concepts or ideas in a discussion of the formation of island chains and hotspots which are indispensable? And then theres the diagram..

I suppose you can pass with the info given there, but for a good pass u need to discuss an actual example, stating the direction of plate movement and the relative ages of each islands in the chain.

What do the rest think?

11:40 PM

 
Blogger HaWi3 said...

hey mr toh, hawa here..my e-mail add is siti_hawa_86@hotmail.com

12:28 AM

 

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