 The geological time scale is a representation of the history on Earth.  The geological time scale was organized based on fossil records.

 The time scale is organized into three main time periods:  Eras  Periods  Epochs

 Eras lasts about tens to hundreds of millions of years and will consist of at least 2 periods.

 Periods are the most commonly used geological time. They last for about tens of millions of years.  Each period is associated with a particular type of rock system.

 Epochs are the smallest unit of geological time. They last several millions of years.

 Scientists have argued for centuries about the origin of life and what occurred. However they do agree on two things:  That Earth is billions of years old.  The condition of Earth and the atmosphere is MUCH different than it is today.

 About 4.6 billion years ago the sun formed from a dust and gas cloud.  Over millions of years space debris collisions lead to the formation of the planets. 

 In the Hadean era, Earth was violent and very hot.  Comets and asteroids crashed into Earth releasing large amounts of heat.  Scientists agree that there was no abundant oxygen until about 2 billion years ago.

 It was not until the end of the hadean era that Earth began to cool down, and large bodies of water formed.  Once water was present, organic compounds could be formed from inorganic compounds.

 Alfred Wegener was the scientist who proposed the Continental Drift Theory through the first few decades of the twentieth century.

 His hypothesis proposed that the continents had once been joined, and over time had drifted apart.  The jigsaw fit that the continents make with each other can be seen by looking at any world map.

 When all the continents are joined together, they are termed a ‘super continent’ AKA Pangaea  Pangaea existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration

 Fossil evidence for Pangaea includes the presence of similar and identical species on continents that are now great distances apart.

 In the case of the Earth, there are currently seven to eight major (depending on how they are defined) and many minor tectonic plates.

 Plate tectonics tells us that the Earth's rigid outer shell (lithosphere) is broken into a mosaic of oceanic and continental plates which can slide over the plastic aesthenosphere, which is the uppermost layer of the mantle.

 The plates are in constant motion. Where they interact, along their margins, important geological processes take place, such as the formation of mountain belts, earthquakes, and volcanoes.

 Both the Earth's surface and its interior are in motion.  The continents are still continously in motion. North America and Asia are VERY slowly moving closer together.