Working Outline
Title: A Cool Early Earth? Source: Scientific American, October 2005 Author: John W. Valley, U. Wisconsin—Madison
Central Idea: Zircon crystals show that there was solid rock and water on the Earth 4.4 billion years ago, 400 million years earlier than previously thought.
Pattern of Organization: Three types of evidence from zircon crystals for solid rock, liquid water, and continents ordered from most reliable to least reliable.
1. Introduction
a. Previous model:
i. Earth 4.5 billion years old by material in meteorites and other methods ii. Previously no igneous rock found older than 4 billion years old, no
sedimentary (requiring water to form) found older than 3.8 billions years ago iii. ―Hadean‖ period – molten rock surface like mantle of Earth. 4.5 – 4.0 billion
years ago.
b. Zircon crystals. ZrSi04 structure. Found in Jack Hills, western Australia.
i. Reliably date to 4.4 billion years ago
ii. Apparently formed in cool, wet environment
iii. Show signs of wear consistent with wind/rain across a continent
2. Body
a. Zircon crystals and uranium-lead dating
i. ZrSi04 structure. Found in Australia.
ii. uranium fits lattice to be a trace impurity but lead atoms too large for lattice
so zircon crystals start out virtually lead-free
iii. known decay rate of uranium to lead allows dating to 1% accuracy = +/- 40
million years by looking at uranium/lead ratio
iv. dozen of zircons older than 4 billion, oldest 4.4 billion years old
b. Oxygen isotope ratios
i. Isotopes of oxygen in zircon. (Recall: isotope = extra neutrons) 99.8% oxygen has 8 neutrons. 18O has 10 neutrons.
ii. Only known way to get high ratio of 18O is by low temperature rocks
chemically interacting with rain or ocean water. Those rocks, buried and melted, retain the high ratio
iii. Ratios for all 4+-billion-year-old zircon crystals were in expected range for
cool wet environments, and not in expected range for Earth’s mantle
c. Rounded surfaces
i. Zircon crystals form with sharp edges and flat faces. Microscope photos show some ancient crystals worn to round.
ii. Number of worn crystals implies they were common and from a widespread
source region, maybe a first continent. If so, source rock could still exist.
3. Conclusion
a. Zircon crystals are the oldest known solid, dating to 4.4 billion years ago, indicating
Hadean age was at most 100,000,000 years long not 500,000,000
b. Zircon crystals formed from rock that had been in a cool, wet environment, so there
was liquid water on Earth before they formed.
c. Zircon crystals were eroded by wind and/or running water, indicating the presence of
a large amount of land.
d. Earth’s surface was suitable for life 400 million years than previously thought. e. Future work: Find & analyze zircons from other parts of world.
[Comment: Points 2C & 3C were replaced with ―Other data‖ points later in the preparation.]
Working Outline
Topic: Voice Visualization for Language Learning
Central idea: The goal of this talk is to convince audience that our method of voice
visualization is useful and practical for people learning English in China.
Pattern of organization: Problem solution pattern 2 (Problem definition / Recommended
solution / Reasons solution is best) modified to give extra emphasis on problem introduction before recommending a specific solution
INTRODUCTION:
I. Main point: Many people in China are language learners
A. Some in formal classes B. Many by themselves
II. Main point: Speaking is the hardest skill
A. Lack of feedback for correct pronunciation B. Difficulty of hearing non-native sounds
III. Computer-based voice visualization can help speaking skills
BODY:
I. Definition of the problem (causes / effects)
A. Speaking a foreign language is harder than listening or writing B. pronunciation of ―foreign‖ sounds is hard even with a tutor
C. in China (and parts of Canada) language tutors/teachers are scarce D. effect: poor pronunciation
II. Explanation of the recommended solution
A. Pitch & stress are keys to understandable accent
B. Computer sound capabilities for reasonable price are now available
C. Student sees/hears model and tries to duplicate with visual/audio feedback D. Real-time analysis vital to effectiveness
E. New analysis techniques run on weak computers
III. Reasons that this is the best solution
A. Practical for China-- low-cost, simple equipment B. Visual feedback can help in absence of tutor
C. Non-native sounds can be visually differentiated, training the ear D. CAL capabilities are useful for whole language course E. Also very useful for tonal languages like Chinese
CONCLUSION:
I. Main point: Research should proceed now.
A. Algorithms not (ever) perfected
B. Equipment options to be investigated
II. Main point: Voice visualization is effective and practical
A. Theoretically sound according to linguists B. Suitable for China and needed
Note: The final version of the talk had a different outline, e.g. III.D was omitted. The working outline changes as you work on it. This is an early version of the outline.