Q3L4

• Geologic Time Scale - is the calendar for events in Earth HIstory
• Geologic Time Scale - divides up the history of the earth based on life-forms that have existed during specific times since the creation of the planet
• The divisions are called geochronologic units
• geo means rock, chronology means time
• Eons - longest subdivision
• Eons - based on the abundance of certain fossils
• Eras - next to longest subdivision
• Eras - marked by major changes in the fossil record
• Periods - based on the types of life existing at the time
• Epochs - shortest subdivision
• Epochs - marked differences in life forms and can vary from continent to continent
• Ages - also referred to as "stages"
• Ages - are the smallest units of geologic time
• Hadean Eon - oldest eon approximately 4.6 billion and about 4.0 billion years ago
• Hadean - is derived from the Greek god of underworld Hades
• Hadean - signify as chaotic in the context of the eon's conditions
• Hadean Eon - it represents the earlier chapters of earth's formation
• Hadean Eon - During these early years, Earth didn't have a stable surface because the planet was characterized by a partially molten surface, volcanism, and asteroid impacts There were no oceans or solid land as we know them today.
• Theia Theory - the moon was formed as a result of a giant impact between earth and a mars-sized protoplanet named Theia
• Hydrothermal Vent Hypothesis - suggests that life's precursors might have originated around hydrothermal vents on the ocean floor
• Accretion and Differentiation - Earth likely formed through the accretion of smaller bodies in the early solar system.
• Accretion and Differentiation - The process of differentiation led to

  the formation of distinct layers, with heavier materials sinking to the core and lighter materials rising to the surface.
• Evidences supporting Hadean Theories

  1. Tilted Earth due to collision
  2. Zircon Crystal - considered as the oldest and toughest minerals on Earth found in Western Australia