Geological Time 1 Relative dating means dates are placed in their proper sequence or order without knowing their age in years a Radioactive dating means you can tell their age in years 2 The magnitude of geologic time Involves vast times millions or billions of years a b An appreciation for the magnitude of geologic time is important because many processes are gradual 3 1950s Fred Hoyle believed that the universe was eternal a Steady State Theory universe was constantly being created and destroyed 4 Atomic bomb is fission it splits atoms a Hydrogen bomb is fusion Two Helium atoms combine to make Hydrogen i When all the Hydrogen is used up a star collapses on itself and creates a black hole if its big enough and supernovas if its smaller 5 Earth is believed to be about 4 5 billion years old 6 Heavier inner planets orbit around a large mass 7 Believed that Jupiter is a failed sun Geologic Time Scale 1 Names came from England where Geologists first described the rocks 2 Precambrian is the basic history of Earth a Algae and single cellular species existed then 3 Paleozoic means old life a Mesozoic means middle life It s the time of the dinosaurs b 65 5 million years ago a meteor struck the Earth c Cenozoic era is the era of mammals i Divided into epochs 4 Paleontologist in Canada discovered a rock that had trilobites from the Cambrian period that were frozen and preserved a Their internal organs were still inside b Called the Cambrian Explosion i 6 of the 15 different species classes were discovered all at once 5 251 million years ago a giant volcanic explosion created the biggest mass extinction of Earth s existence 6 Triassic period had the giant insects 7 Jurassic period was ended by a meteor crashing into the Earth 8 Impression of the crater is found near Cozumel and Cancun The Nature of Scientific Inquiry 1 Science assumes the natural world is consistent and predictable 2 The goal of science is to discover patters in nature and use the knowledge to make predictions 3 Scientists collect facts through observation and measurements a In science you know something is true when a hypothesis becomes a theory that is tested multiple times and is proven to be true 4 The only thing that is definite is mathematics Earth s Internal Structure 1 Continental crust is predominantly granite which is an igneous rock a Rises to the surface as an intrusive igneous rock melts and cools inside the Earth s core 2 Oceanic crust is made of basalt 3 You can tell the weight difference between basalt and granite 4 Continental crust is thicker than oceanic crust a Floats on top of the upper mantel or the asthenosphere which flows slowly 5 We know what s in the Earth s crust a Magma chamber is about 700 miles beneath the Earth i Piece of rock breaks off and is brought to the surface through volcanic ii Find fragments of xenoliths that can t be melted in magma chambers b Sun s gravitational pull brings meteorites to it Earth blocks the path of the i Meteorites can be found in Antarctica and the Sahara Desert ii Asteroid belt is formed by the Sun and Jupiter s gravity pulling apart a chambers meteorite to the Sun protoplanet 1 Rocky meteorites and iron and nickel meteorites a Iron and nickel meteorites form the core of a planet c Seismic waves are vibrations from the inside of the Earth i Speed of waves are determined by the density of the material that it moves through 1 Denser the material the faster it goes ii Some seismic waves won t go through certain materials