Introduction to Physical Geology Lecture 2 Introduction to Physical Geology

Lecture Outline I Geological Paradigms II Origins Physical Geology Lecture Outline I Geological Paradigms II Origins A) The Solar System B) The Earth III Fundamental Concepts of Physical Geology A) Geologic Time B) The Earth's Structure i. Earth's Layers ii. Plate Tectonics - From Continental Drift to Plate Tectonics - Lithospheric Plates - Plate Boundaries C) The Rock Cycle IV Planetary Geology V Conclusions

Geological Paradigms Physical Geology paradigm, n: a collection of beliefs shared by scientists; a set of agreements about how problems are to be understood James Ussher (1581-1656) catastrophism James Hutton (1726-1797) uniformitarianism rock cycle Charles Lyell (1797-1875) geologic time Alfred Wegener (1880-1930) continental drift

Origin of the Solar System The Nebular Hypothesis Physical Geology Origin of the Solar System The Nebular Hypothesis Palomar Observatory

Origin of the Solar System The Nebular Hypothesis Physical Geology Origin of the Solar System The Nebular Hypothesis

Origin of the Solar System The Nebular Hypothesis Physical Geology Origin of the Solar System The Nebular Hypothesis physical collision gravity clumps of dust grains (cm) Planetesimals (km) planetesimals (10-100 km) protoplanet (100-1000km)

The Solar System What is a Planet? Physical Geology The Solar System What is a Planet? (1) A “planet”1 is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit. (2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2 , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite. (3) All other objects3 except satellites orbiting the Sun shall be referred to collectively as “Small Solar-System Bodies”.

Origin of the Earth Geological Differentiation Physical Geology Origin of the Earth Geological Differentiation Earth melted by: gravitational energy left from formation of planet meteor bombardment radioactive decay Gravity concentrated denser materials (Ni & Fe) in center Less dense materials (silicates) forced to outer layers Crust became stable after 1 billion years Compositional Zones Crust Continental Oceanic Mantle Core Outer (Liquid) Inner (Solid)

Fundamental Concepts Earth's Layers Physical Geology Fundamental Concepts Earth's Layers Compositional Zones Core Solid inner core Liquid outer core Radius of ~3500 km 16.2% of Earth's vol. 31.5% of Earth's mass Generates Earth's magnetic field Mantle Thickness ~2900 km 82.3% of Earth's vol. 67.8% of Earth's mass Crust Oceanic – 4-20km thick Continental – 30-70km thick Mechanical Zones Core Mesosphere Lower mantle Rigid Very Hot Capable of gradual flow Asthenosphere "weak" layer Convecting mantle Soft and readily flows Lithosphere Crust and Upper Mantle Brittle

Fundamental Concepts Geologic Time Physical Geology Fundamental Concepts Geologic Time Phanerozoic Eon -"Eon of Evident Life" Paleozoic Era -"Era of Old Life" Mesozoic Era -"Era of Middle Life" Cenozoic Era -"Era of Modern Life" Divisions Eon Era Period Epoch Age

Fundamental Concepts Plate Tectonics - The Evidence Physical Geology Fundamental Concepts Plate Tectonics - The Evidence

Fundamental Concepts Plate Tectonics - The Ocean Floor Physical Geology Fundamental Concepts Plate Tectonics - The Ocean Floor Mid-Ocean Ridge System

Fundamental Concepts Plate Tectonics - The Ocean Floor Physical Geology Fundamental Concepts Plate Tectonics - The Ocean Floor Mid-Ocean Ridge System underwater mountain range 80,000 km long 1500-2500 km wide up to 3000 m above sea floor rift valley, 1-2 km deep, runs along axis 4000 km wide fracture systems

Fundamental Concepts Plate Tectonics - The Ocean Floor Physical Geology Fundamental Concepts Plate Tectonics - The Ocean Floor magnetic striping crustal age

Fundamental Concepts Plate Tectonics - The Ocean Floor Physical Geology Fundamental Concepts Plate Tectonics - The Ocean Floor

Fundamental Concepts Plate Tectonics - The Engine Physical Geology Fundamental Concepts Plate Tectonics - The Engine

Fundamental Concepts Plate Tectonics - Lithospheric Plates Physical Geology Fundamental Concepts Plate Tectonics - Lithospheric Plates

Fundamental Concepts Plate Tectonics – Plate Boundaries Physical Geology Fundamental Concepts Plate Tectonics – Plate Boundaries

Fundamental Concepts The Rock Cycle Physical Geology Fundamental Concepts The Rock Cycle Atmospheric Processes Weathering Physical Weathering Chemical Weathering Biological Weathering Sediment Transport Lithospheric Processes Burial Compaction and Cementation Heat and Pressure Stress Plate Tectonics Exposure

Planetary Geology Physical Geology Venus Europa Jupiter Mars Io Magellan Galileo Mars Io Galileo Viking 1 Voyager 1

Planetary Geology Mars Physical Geology Physical Geology Planetary Geology Mars