Earth's Early Atmosphere and Oceans, and the Origin of Life

About this book

Earth's Early Atmosphere and Oceans, and the Origin of Life provides a comprehensive treatment of the chemical nature of the Earth's early surface environment and how that led to the origin of life. This includes a detailed discussion of the likely process by which life emerged using as much quantitative information as possible. The emergence of life and the prior surface conditions of the Earth have implications for the evolution of Earth's surface environment over the following 2-2.5 billion years. The last part of Earth's Early Atmosphere and Oceans, and the Origin of Life discusses how these changes took place and the evidence from the geologic record that supports this particular version of early and evolving conditions.

Contents

- Introduction
- Why this book? / What I am trying to do
- Four previous treatments - Oparin, Rubey, Walker, and Holland
- Outstanding problems
- Accretional history of Earth
- Accreting materials
- Volatile components and total volatiles available
- Sequence and rates of events - accretion time
- State of surface near end of accretion
- Nature of final accretional phase
- Processes of degassing
- Impact degassing
- Small impactors
- Large impactors
- Intermediate impactors
- High temperature degassing of accreted solids
- Low temperature degassing of accreted solids - importance of water produced during initial phase of late accretion
- Evidence from field and laboratory studies
- Atmospheric processing of degassed volatiles
- Photochemistry in brief
- Recycling of C and N compounds in the surface and near-surface environment
- The nature of the early ocean
- Early Archean "geography"
- Global ocean should be obvious
- Ocean ridge systems and hot-spots
- Continental growth - processes and history
- Proto-island arcs and shorelines
- Degassing processes
- Prebiotic chemistry - why we should pay attention to this
- Availability of critical C-N species
- Availability of phosphorus (possible complexing with organics)
- Concentration processes - "Warm pond"?
- Eigen's hypercycle and the emergence of life
- Key role of tRNA
- The nature of tRNA and why/how it might be produced in quantity
- tRNA as a dimer - and other similar RNA
- How much tRNA and how many of them?
- Does tRNA code for useful polypeptides?
- How the carbon-rich surface is key to emergence of life
- How much tRNA can be made? Compare to polypeptide numbers and probability of "functional" tRNA assemblies
- Micelles/protocells
- Why do we get tRNA, why does tRNA look like that?
- Evolution of Earth starting with a carbon-rich surface
- Subduction of organics and cycling of carbon through time
- History of CO₂ production
- Origin of photosynthesis
- Hydrogen loss, photosynthesis and increase in oxidation state
- Transition of oxidized atmosphere
- Implications of this model
- Faint Young sun resolved
- Carbon isotope systematic
- Early Archean lithology
- Cratonisation and the carbon cycle
- Delay in oxidation of atmosphere and surface
- Climate transition on Mars and Martian geology today
- Conclusions

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Biography

As a graduate student at the University of Washington, Dr. George Shaw focused on experimental geophysics, especially high pressure measurements of elastic properties. These studies continued through an NSF post-doctoral fellowship at Edinburgh, Scotland, at the Department of Geology and Geophysics at the University of Minnesota, and to a lesser extent after he took up a position at Union College. During his time at Minnesota Shaw was awarded an American Geophysical Union Congressional Science Fellowship. He spent the year working for a congressman from Washington State on energy and environmental issues, and particularly on the formulation and passage of the Nuclear Waste Policy Act of 1982. Dr. Shaw left Minnesota in 1988 to take up an endowed chair with the responsibility of restarting and developing a geology department at Union, a small private liberal arts college. At Minnesota he developed with a colleague a course in energy resources and policy, which we taught for about ten years and which he continued to teach at Union. About fifteen years ago Dr. Shaw initiated a course called "Great Moments in the History of Life" beginning with the origin of the universe and chemical elements and continuing through the Anthropocene. This revived an old interest in early Earth history and especially the conditions preceding and surrounding the origin of life. This book is the result of that revived interest.