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Earth sciences overview. Chris Paola 4-8025 SAFL & Pills 30b. Plan for next two weeks. Today: overview of earth sciences Friday: Nonlinearity and nonequilibrium case examples Monday: paleoclimate (with Emi Ito) Friday: ESci connections to other fields.

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earth sciences overview

Earth sciences overview

Chris Paola


SAFL & Pills 30b

plan for next two weeks
Plan for next two weeks
  • Today: overview of earth sciences
  • Friday: Nonlinearity and nonequilibrium case examples
  • Monday: paleoclimate (with Emi Ito)
  • Friday: ESci connections to other fields
journals and societies
Journals and societies
  • American Geophysical Union (Eos, Journal of Geophysical Research, Water Resources Research)
    • Nearly all areas of earth science: atmosphere, oceans, surface (inc. hydrology), geobiology, lithosphere, deep earth)
  • Geological Society of America (Geology, GSA Today, GSA Bulletin)
    • All areas of geology, geobiology, and geochemistry
  • European Geophysical Union
  • Terra Nova
the ancient kingdoms
The Ancient Kingdoms
  • Mineralogy & petrology
  • Structural geology
  • Paleontology
  • Igneous, metamorphic, sedimentary geology
  • Surficial and Quaternary geology
  • Geophysics
  • Geochemistry
  • Geobiology
research threads
Research threads
  • Observation and inference on planetary scales: atmosphere, ocean, deep interior
  • Mechanical properties & materials
  • Extreme conditions (e.g. heat, pressure)
  • Extreme events (e.g. meteorite impact)
  • Co-evolution of Earth and life
  • Spatial structure through time: surface
  • Spatial structure through time: lithosphere
  • Comparative planetology
major intellectual contributions
Major intellectual contributions
  • Uniformitarianism: present as key to past
  • Deep time, evolution, age of Earth
  • Plate tectonics
  • “Mechanism”: application of physical laws over planetary scales
  • Neocatastrophism
  • Alternative earths and planetary history: past as key to (possible) futures
plate tectonics a simple estimation problem
Plate tectonics: a simple estimation problem
  • Plate horizontal motion rates: of the order of cm/year
  • Relation of vertical to horizontal rates: order 0.1
  • What (order of magnitude) should be the concentration of sediment in river water?
mechanism how plates bend
Mechanism: how plates bend

The theory describing plate deflection is identical to that used for beams in structural engineering!

alternative earth mesozoic greenhouse
Alternative Earth: Mesozoic greenhouse
  • Warm, ice-free poles
  • High CO2
  • Weak oceanic, atmospheric circulation
  • Oceanic anoxic events
  • Land initially assembled as one ‘supercontinent’
the earth in equilibrium
The Earth in equilibrium
  • Atmospheric temperature
  • Steady state erosion
  • Steady state deposition
non equilibrium the variability around the mean
Non equilibrium – the variability around the mean
  • It’s hard to think of examples of geologic systems that don’t fluctuate:
    • Stream flow
    • Plate motion (earthquakes)
    • Sedimentation
    • Heat flow (volcanoes)
    • Erosion rates
  • One basic question is: what is the distribution of fluctuation energy over time and/or space scales?
example earthquake distribution follows gutenberg richter law
Example: earthquake distribution follows Gutenberg-Richter law

An example of a “power law” – a common distribution

Nonlinearity: Earth sciences have provided the type examples for three major classes of new nonlinear phenomena of C20
  • Fractals: coastline of Britain (contour line)
  • Chaos: simplified atmospheric model
  • Self-organized criticality: sand pile (a few minor problems…)
non linearity self organization pattern formation
Non-linearity: self-organization & pattern formation
  • Plate tectonics
  • Fault systems
  • Banding in minerals
  • River networks
  • Bedforms and bars

Canyonlands, UT

Rio Salado, NM

trends and culture
Trends and culture
  • Dominant influence of finding resources
    • Minerals
    • Fossil fuels: coal, hydrocarbons
    • water
  • From story-telling to advanced mathematics
    • Wavelet analysis invented in geophysics
    • Historical tradition – we like a ‘good story’
    • Induction vs deduction – detectives vs theorists
    • Central role of field work
    • Is prediction possible? How to test models in historical sciences
trends and culture23
Trends and culture
  • Research trends:
    • Crossing disciplines, e.g. emergence of geobiology
    • Quantification & theory
    • New methods
    • Major limitations:
      • Access to information
      • Age control
new methods
New methods

New research made possible by new measurement techniques


new methods25
New methods

High-res bathymetry

new methods26
New methods

Dating methods for surface materials and short time scales

Cosmogenic radionuclides (CRN)

new methods27
New methods


new methods28
New methods

High res 3D seismic reflection

research frontiers
Research frontiers
  • Complexity, natural variability, and predictability
    • Natural variability in surface morphology
    • Can we forecast earthquakes? Floods?
    • Big problem seems to be systems that are too random to simulate directly, too ordered to use only statistics
  • Long-range connections (“teleconnections”) in the Earth system
    • Ocean/atmosphere coupling
    • Deep earth/surface earth coupling – does erosion cause mountain belts?
  • Role of microbes
research frontiers30
Research frontiers
  • Drivers and history of plate tectonics
    • Role of life?
  • Atmospheric history and regulation
    • Role of life?
  • Origin of life
  • Civil engineering: hydrology, geomorphology, structural geology, rock mechanics
  • Ecology: geobiology, paleoecology
  • Computer science: data bases and data mining; numerical earth modeling
milankovitch orbital cycles
Milankovitch orbital cycles

1. Eccentricity

Circular orbit, no eccentricity.

Orbit with 0.5 eccentricity

Periods: 413,000, 95,000, and 136,000 years. Overall dominant ~ 100,000 year cycle

Range: -0.03 to +0.02).

Present value: 0.017.

milankovitch orbital cycles33
Milankovitch orbital cycles

2. Axial tilt (obliquity)

Period: 40,000 years

Range: 2.4 degrees

Present value: 23.44 degrees

milankovitch orbital cycles34
Milankovitch orbital cycles

3. Precession

Period: 20,000 years

Range: entire orbit

Present value: perihelion during SH summer, aphelion during NH summer

milankovitch orbital cycles linear superposition but nonlinear earth response36
Milankovitch orbital cycles: linear superposition but nonlinear Earth response

Vostok ice core data