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Objectives Define and understand the branches of geology. Explain the key steps used to study science. Describe the formation of planets in the solar. system, including Earth. Understand what makes Earth unique. Explain the importance of time and change in geology.
What is Geology? Geology The scientific study of Earth. Physical geology Understanding processes and materials. Historical geology Sequence of geologic events Why did the dinosaurs suddenly die out 65 million years ago?
Using the scientific method Scientific method The way a scientist approaches a problem Varies in detail Includes five key steps Not necessarily a linear methodology, though
Using the scientific method Observations and data gathering Formulating hypothesis Hypothesis: a plausible, but not yet proven, explanation for how something happens Testing hypothesis Formulating theory Theory: a hypothesis tested and supported by observation and experimentation Formulating law/ theory
Earth system science The system concept Breaking large complex problems into smaller pieces without loosing sight of the connection. Systems typically fall into two major categories: Closed Open
The earth system Geosphere The solid Earth, as a whole Biosphere All living and recently dead organisms Atmosphere The gasses that surround Earth Hydrosphere Water and ice, both on the surface and underground
The life zone Zone where all known life exists Found 10 kilometers above or below Earth’s surface
Cycles and interactions Hydrologic cycle Describes the movement of water Rock cycle Processes that form, modify, transport or break down rock Tectonic cycle Processes that drive the movement and interactions in the lithosphere
Earth in space The solar system Earth is one of eight planets in orbit around the Sun Also includes 140 moons, asteroids, comets meteoroids
The origin of the solar system Nebular hypothesis The solar system coalesced out of a swirling cloud of interstellar dust/gas Called a nebula. Sun born from a nuclear reaction called fusion Fusion combines hydrogen atoms to form helium
The origin of the solar system Planetary accretion Outer portions of solar nebula cooled into disks of debris. Random collisions formed clumps that eventually grew large enough to pull in remaining debris through gravity.
The origin of the solar system Meteorite A fragment of extraterrestrial material that falls to Earth. Violent collisions between planets and meteorites important aspect of planetary accretion
The origin of the solar system Differentiation: the layering of terrestrial planets based on chemical composition Crust: outermost compositional layer Thin, low-density and rocky Mantle: middle layer of Earth Rocky, intermediate density Core: innermost layer High density and metallic Other planets in the solar system exhibit differentiation
What makes Earth unique? Atmosphere Rich in oxygen Hydrosphere Contains water as solid, liquid or vapor Biosphere Full of living organisms Regolith Blanket of loose debris covering Earth i.e., soil
What makes Earth unique? Plate tectonics The movement and interactions of large fragments of Earth’s lithosphere, called plates Responsible for shaping continents and ocean basins, as well as distribution of volcanoes and earthquakes Oceanic crust Thinner, denser and younger, underlying the ocean basins Relatively thin and comprised of basalt (igneous rock type) Continental crust Older, thicker, and less dense, the bulk of earth’s landmasses Generally thick and comprised of granite (igneous rock type) Unique to Earth
The Ever-Changing Earth Earth is dynamic system Uniformitarianism Proposed by James Hutton The processes governing the Earth systems today have operated in a similar manner throughout geologic times “the present is the key to the past”
The Ever-Changing Earth Time and change Physical processes on Earth have not changed , but the physical conditions on Earth have changed dramatically.
Why study geology? Earth is our home planet We depend on Earth for all our material resources Limited resources require knowledgeable and thoughtful management Earth’s physical and chemical processes affect us We need to appreciate our own role in geologic change
Critical Thinking In what ways do geologic processes affect your daily life? Name some examples of artificial systems. Are they closed or open systems? If you were an astronomer studying young suns, what kind of evidence would you look for in order to test the nebular hypothesis?
