Ch. 1 Introduction to Geology Topics Covered The Science of Geology People and Environment Historical Notes Geologic Time Scientific Inquiry Earth’s Spheres The Earth System The Evolution of the Planet Earth
The Science of Geology • What does the word Geo mean? • Two fields of Geology – physical and historical • Geology deals with – • Natural hazards, • Resources • Environmental Issues-sometimes what looks like a benefit to society may have the opposite effect
Historical Notes about Geology • subject of Greek writings 2300 years ago • Aristotle’s theories carried on to the Middle Ages • 1600’s – James Ussher- Earth was created in 4004 BC - Catastrophism- earth’s features were produced by sudden catastrophies.
Modern Geology • Late 1700’s with James Hutton • Uniformitarianism – “the physical, chemical, and biological laws that operated today have also operated in the geologic past.” • Geologic processes take a very long time, so earth must be very old. • North American continent is lowered by 3cm/1000yrs. • It would take a little less than 100 million years to lower the Wasatch Mountains.
Radioactivity • Discovered in 1896 • Earth is 4.5 billion years old • Geologic Time scale developed using Relative Dating –events are placed in order without knowing their exact age.
The Law of Superposition-youngest rocks on top, oldest rocks on the bottom. http://facweb.bhc.edu/academics/science/harwoodr/Geol101/Labs/Dating2/Index.htm
Scientific Inquiry • Science is systematic, consistent, and predictable to some extent • There are patterns in nature • Data collection • We form a hypothesis or model to explain occurances • A hypothesis must be tested! • When a hypothesis has been thoroughly tested it can be called a Theory
Earth as a System • The interconnection of land, air, water, and life forms. • Systems are interacting parts to a whole • Closed system – energy and matter do not exit the system, it is self contained • Open system – energy flows in and out.
Open system Hurricane Snow storm What are some of the factors that influence these open systems?
Feedback Loops Positive feedback Negative feedback • Tends to promote more of itself. A leads to more B which leads to more A. • System is unstable and tends to go out of control • Positive does not necessarily mean good as it destabilizes • Tends to stablize a system and keep it from being out of control. • It is negative because it goes against the disruption.
Feedback Mechanisms negative feedback– maintain stability. positive feedback - drive to promote change • Which images are positive, which are negative?
Examples of Positive feedback in climatology A warmer climate: A colder climate: • A warmer atmosphere will, due to increased evaporation and decreased condensation, contain more water vapour which is a greenhouse gas so it will warm the atmosphere further. • A warmer atmosphere will melt ice and this changes the albedo which further warms the atmosphere. • A colder climate will cause ice caps and glaciers to grow changing the albedo which further cools the atmosphere. • Methane hydrates can be unstable such that a warming ocean could release methane which is a greenhouse gas
Cycles of the Earth’s Systems Hydrologic, Carbon, Rock Cycle Interface = a boundary where different parts of a system interact In this picture the water cycle and the hydrologic cycle interface. How?
Check out GEODe Ch. 1 Introduction • Key Terms - • Readings for next class = • summary page 30 • Review questions pg. 31 (know the answers to questions 1 - 8) • Read Ch. 2
Key Terms to know • Atmosphere • Biosphere • Catastrophism • Geology • Historical geology • 3 types of rocks • Physical geology • Relative dating • The law of superposition • Uniformitarianism • Theory vs. hypothesis