Geology - the study of the Earth, the processes that shape it, and the resources that could be obtained from it.
Physical Geology - deals with the materials that comprise the Earth and the processes that affect it (e.g., Volcanology, Seismology, Environmental Geology, Engineering Geology, Mining Geology, Petroleum Geology, Mineralogy, Petrology, Geomorphology, Geophysics, Geochemistry, Planetary Geology) Historical Geology - the study of the origin and evolution of the Earth through time (e.g., Paleontology, Stratigraphy, Geochronology)
Catastrophism – proposed by Georges Cuvier; advocates the idea that sudden, worldwide catastrophes are the agents of change that alter the physical features of the Earth over time and that the latter remains unchanged in between these periods of upheavals; widely accepted by theologians in the early 1800s due to similarity with Biblical events such as Noah’s Flood (James Ussher, mid-1600s) Uniformitarianism - proposed by James Hutton (late 1700s, “The Father of Modern Geology”), modernized by Charles Lyell (mid1800s); “The present is the key to the past”; advocates the idea that the Earth is continuously modified by geologic processes that have always operated throughout time (at different rates), and that by studying them we can understand how the Earth has evolved through time Relevance to daily life
Everything we use comes from the Earth
Particularly in the form of natural resources provided through application of geologic knowledge. Construction - cement, concrete and asphalt
Fuel, light and heat - oil, gas and coal
Prediction and avoidance of hazards, earthquakes, floods, volcanoes, landslides, erosion.
Lecture 2: The Planet Earth
Cosmology: study of the universe and its origins and processes Formation of the Universe: Big Bang Theory
Formation of the Solar System: Nebular Hypothesis
The Big Bang Theory: proposed by the Belgian priest Georges Lemaître in the 1920s ; contends that the Universe originated from a cosmic explosion that hurled matter in all directions 15 and 20 billion years ago; Edwin Hubble justified Lemaître’s theory through observations that the Universe is continuously expanding; galaxies are moving away from each other
Evidence of Big Bang: red shift and cosmic background microwave radiation
metric expansion of space
Nebular Hypothesis: proposed by Emaneuel Swedenborg, Immanuel Kant and Pierre Simon de Laplace in the 18th century; the solar system originated from a single rotating cloud of gas and dust, starting 4.6 billion years ago, which contracted due to gravity
1. The Big Bang produced enormous amount of matter: rotating cloud of gas and dust. 2. The rotating gas-dust cloud began to contract due to gravity. Most of the mass became concentrated at the center, forming the Sun.
3. The remaining matter condensed to form the planets.
The Sun: a middle-aged star; mostly made up of hydrogen, the principal product of the Big Bang; sun’s center became compressed enough to initiate nuclear reactions, consequently emitting light and energy (sun became a star)
The Planets: composition depended on distance from the sun; planets nearest the sun contained high-temp minerals (e.g. iron) while those that are far away contained lower-temp materials (e.g. methane and ammonia, and some that contained water locked in their structures) Mercury, Venus, Earth, Mars: inner or terrestrial planets (nearest the sun); rocky composition: largely silicate rocks and metals (Si, Fe, O)
Jupiter, Saturn, Uranus, Neptune: giant or Jovian planets (outer planets; far from the sun); lack solid surfaces: in gaseous or liquid form; composition: light elements (H, He, Ar, C, O, Ni) The Earth: started as a “dust ball” from the nebular gas and dust brought together by gravity (accretion), which was heated (heating) and eventually segregated into layers (differentiation) as it cooled; when cooling set in, the denser...