Today we will look at a topic that you know a bit about: sea-floor spreading. Most textbooks present sea-floor spreading and its evolution into plate tectonics in a manner that emphasizes the basic evidence. Our interests are slightly different: we want to put this history into a timelines so that we can consider how the different lines evidence came together. The readings present some of the “stories” behind the research (which are revealing) but we really are focusing on the integration of various geophysical and geological ideas across this development. As you read through the various readings on these two topics, please keep track of the key papers, when they were published, and what was their essential contribution.

You will find a lot of familiar information as you read about sea-floor spreading and plate tectonics; however, some ideas or concepts may be confusing or a bit hazy, so please take note of them and ask your group (or me) for clarification. I can assure you that you will not be the only person who may be confused on some of this!

Harris sections 31

Section 31 presents the development of sea-floor spreading from Hess’ “geopoetry” (1960) through the “conversion” of Lamont (1966). You may have read some of the papers mentioned in various geology classes – you have certainly seen some of the key diagrams in textbooks!

Wood (1985) Chapter 6: A naval engagment, p. 148-154

If you have not read this section yet, this is the time to do so. It works through how the idea of sea-floor spreading (in the Vine-Matthews-Morley sense) came about.

Allegre (1988) p. 59-90

This selection from Allegre (and that on continental drift) provide a more detailed narrative than in my notes for these rapid developments. He tends to includes some reflective comments/narrative along the way, reflecting his thoughts on how this came about – some of this can be skimmed (interesting as it is).  You will want to examine the illustrations in these selections.

Questions

• The Vine-Matthews-Morley hypothesis of sea-floor spreading
  • What was the basic idea of this model
  • What data and related concepts were brought together?
  • What were the objections?
  • What finally changed the minds of the Lamont group (the most important skeptics)
• In a broader perspective
  • To what extent did sea-floor spreading depend upon the prior work on terrestrial paleomagnetism and marine data?
  • How did this change the basic view of ocean basins?
• Please list the major developments/publications in this story (most of which are in the Harris notes). This will be the baseline material for the group work on the evolution of continental drift to plate tectonics. And yes, the1960s are going to get crowded!

Also: You will be working on your posters.  Please be ready to work on the layout, text and figure choices.

Links to course homepage and course schedule.