# Dependency Tree For The Development Of Plate Tectonics

This post is really rough and mostly meant to refer back to when I’ve produced more work on the subject. Proceed at your own risk.

Introduction
============

As I [mentioned](https://acesounderglass.com/2022/08/31/impact-shares-for-speculative-projects/) a few weeks ago I am working on a project on how scientific paradigms are developed. I generated a long list of questions and picked plate tectonics as my first case study. I immediately lost interest in the original questions and wanted to make a dependency graph/tech tree for the development of the paradigm, and this is just a personal project so I did that instead.

I didn’t reach a stopping point with this graph other than “I felt done and wanted to start on my second case study”. I’m inconsistent about the level of detail or how far back I go. I tried to go back and mark whether data collection was motivated by theory or practical issues but didn’t fill it in for every node, even when it was knowable. Working on a second case study felt more useful than refining this one further so I’m shipping this version. 

“Screw it I’m shipping” is kind of the theme of this blog post, but that’s partially because I’m not sure which things are most valuable. Questions, suggestions, or additions are extremely welcome as they help me narrow in on the important parts. But heads up the answer might be “I don’t remember and don’t think it’s important enough to look up”. My current intention is to circle back after 1 or 2 more case studies and do some useful compare and contrast, but maybe I’ll find something better.

![](https://lh5.googleusercontent.com/WfNT2hsdDJ038-JlqKUwCMEpL5kk7BjnYH7BtFZuOXq5hV-VSuRSPDUlVzNTXBPzMPOBq4XyO0gwuSGbPH5pVTd5oH0DMDLz_L-IWI5sxVN5lZ573qgqtTB7cImi4-doDT65HfRhfloNCirPkNjnRw_hJbNQ98tXSaHG_S9R2q3JoY1vQ84PJ70Y0w)

([Readable version here](https://drive.google.com/file/d/10UsD2xdRc2mwCxHnKOsnqhU_gZk65RNv/view))

And if you’re really masochistic, here’s the [yEd file](https://drive.google.com/file/d/1qtI1jy0jEOF4FlPlJNWPt4F8YIkTDBmr/view?usp=sharing) to play with.

Scattered Thoughts
==================

Why I chose plate tectonics
---------------------------

*   It’s recent enough to have relatively good documentation, but not so recent the major players are alive and active in field politics.
*   It’s not a sexy topic, so while there isn’t much work on it what exists is pretty high quality. 
*   It is \*the only\* accepted paradigm in its field (for the implicit definition of paradigm in my head).
*   Most paradigms are credited to one person on Wikipedia, even though that one person needed many other people’s work and the idea was refined by many people after they created it. Plate tectonics is the first I’ve found that didn’t do that. Continental drift is attributed to Alfred Wegener, but continental drift is not plate tectonics. Plate tectonics is acknowledged as so much of a group effort wikipedia doesn’t give anyone’s name.

Content notes
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*   This graph is based primarily on [Plate Tectonics: An Insider’s History of the Modern Theory](https://amzn.to/3BPStf5) of the Earth, edited by Naomi Oreskes. It also includes parts from [this lecture by Christopher White](https://www.youtube.com/watch?t=1836&v=Sah7JIajGPg&feature=youtu.be), and Oxford’s [Very Short Introduction to Plate Tectonics](https://amzn.to/3Si4jWh).
*   Sources vary on how much Alfred Wegener knew when he proposed continental drift. Some say he only had the fossil and continental shape data, but the [White video](https://youtu.be/Sah7JIajGPg?t=1836) says he had also used synchronous geological layers and evidence of glacial travel.
    
    *   I tried to resolve this by reading Wegener’s original paper ([translated into English](https://t.co/LceQcNQPNz)) but it only left me more confused. He predicted cracks in plates being filled in by magma, but only mentions fossils once. Moreover he only brings them up to point to fossils of plants that are clearly maladapted to the climate of their current location, not the transcontinental weirdnesses. He does casually mention “Concerning South America and Africa, biologists and geologists are in close agreement that a Brazilian–African continent existed in the Mesozoic”, but clearly he’s not the first one to make that argument.
    *   I alas ran out of steam before trying Wegener’s book.
    
    *   I was stymied in attempts to check his references by the fact that they’re in German. If you really love reading historic academic German and would like to pair on this, please let me know.
    *   I stuck to just the fossil + fit data in the graph, because White is ambiguous when he’s talking about data Wegener had vs. data that came later.
    *   White says the bathymetry maps showing the continental shelves had a much better fit than the continents themselves didn’t come out until after Wegener had published, but [this paper](https://colors.uconn.edu/wp-content/uploads/sites/1423/2015/09/Dierssen_2014_ENRHistory.pdf) cites sufficiently detailed maps of North America’s sea floor in 1884. It’s possible no one bothered with South America and Africa until later.
*   A lot of the data for plate tectonics fell out of military oceanography research. Some of the tools used for this were 100+ years old. Others were recently invented (in particular, magnetometers and gravimeters that worked at sea), but the tech those inventions relied on was not that recent. I think. It’s possible a motivated person could have gathered all the necessary evidence much earlier.
*   Sources also vary a lot on what they thought was relevant. The White video uses continental shelf fit (which is much more precise than using the visible coastline) as one of the five pillars of evidence, but it didn’t come up in the overview chapter of the Oreskes book at all.
*   This may be because evidence of continental drift (that is, that the continents used to be in different places, sometimes touching each other) is very different than evidence for plate tectonics (which overwhelmingly focuses on the structure of the plates and mechanism of motion). 

Process notes
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*   At points my research got very bogged down in some of the specifics of plate tectonics (in particular, why were transform faults always shown perpendicular to mountain ridges, and how there could be so many parallel to each other?). This ended up being quite time consuming because I was in that dead zone where the question was too advanced for 101 resources to answer but advanced resources assumed you already knew the answer. In the end I had to find a human tutor.
*   This could clearly be infinitely detailed or go infinitely far back. I didn’t have a natural “done” condition beyond feeling bored and wanting to do something else. 
*   I only got two chapters into Oreskes and ⅔ through Very Short Introduction. 
*   I didn’t keep close track but this probably represents 20 hours of work, maybe closer to 30 with a more liberal definition of work. Plus 5-10 hours from other people.
*   In calendar time it was ~7 weeks from starting the Oreskes book to scheduling this for publishing.
*   You can see [earlier drafts](https://twitter.com/acesounderglass/status/1562324101598851072) of the graph, along with some of my notes, on Twitter.

Acknowledgments
===============

Thanks to several friends and especially Jasen Murray for their suggestions and questions, and half the people I’ve talked to in the last six weeks for tolerating this topic.

Thanks to Emily Arnold for spending an hour answering my very poorly phrased questions about transform faults.

Thanks to my Patreon patrons for supporting this work, you guys get a fractional [impact share](https://acesounderglass.com/2022/08/31/impact-shares-for-speculative-projects/).