Science for living Us Demonstrate a Knowledge of Earth Science 2 credits

Element 1: Describe the structure of the Earth. Features of the Earth include the mantle, core, crust and plates.

THE STRUCTURE OF THE EARTH crust mantle Outer core Inner core 1

Think about? What moves when there is an Earthquake? What comes out of volcanoes? What is the pumice that you find around Taupo Lake? Which section is the hottest? Which section contains liquid metal? Which section contains solid metal?

LAYERS OF THE EARTH- what’s it made up of? Crust – thin, solid rock. Broken into about 20 plates. Mantle – molten rock (magma), heated from the core and moving in convection currents which moves the plates. Outer core – mainly molten iron and nickel. Inner core – solid iron due to immense pressure. NB: as you move deeper into earth pressure and heat increases.

Movement of plates caused this

Tectonic plates Crust is divided into plates which move around on the moving magma below. They can collide or pull away. They cause volcanic activity. They cause Earthquakes as the plates collide and rocks break. Ring of Fire is the edges of the pacific plate – the collisions cause a lot of volcanic activity.

THE MAJOR TECTONIC PLATES

PLATE TECTONICS Earth’s crust is made of around 11 large tectonic plates and several smaller ones. Convection currents in the Mantle cause the plates to move slowly. Plate tectonics (movement) cause Earthquakes and volcanic activity. Plates consist of continental crust and oceanic crust. NZ lies on the boundaries of the Pacific and Australian plates.

San Andreas Fault – Tectonic Plates colliding – North American Plate and Pacific Plate.

COLLISION OF THE AUSTRALIAN AND PACIFIC PLATES

New Zealand's deep earthquakes from become deeper from east to west

THREE GROUPS OF ROCK MAKE UP THE EARTH’S CRUST Igneous – formed when magma cools and solidifies, in an around volcanoes. Sedimentary – formed from sediment (sand, pebbles, shells) at bottom of a body of water, eg, lake, river, sea, swamp. Metamorphic – formed when other rocks are heated and compressed deep within the Earth’s crust, often near magma.

Sedimentary Rocks Sediment wash down into the ocean. They may contain shells or fossils. Layered. Sediments are cemented together. They are pushed up out of the water by tectonic plate movement. Eg, Sandstone, Limestone

Sandstone Sedimentary. Formed on the beach from sediments of sand. Soft, grainy. Mudstone is also a sedimentary rock with fine particles. Predominant in Marlborough as Greywacke.

Limestone Limestone is found in cliffs. It has fossil shell remains in it because it was formed on the beach which has shellfish on it. A hard sedimentary rock which is often the last to erode.

Limestone of Cathedral Caves

Sawcut gorge davidwallphoto.com

Igneous Rocks Rocks are pushed down into the mantle and become molten. Molten rock cools in the crust to form solid, igneous rocks. Or, the magma comes out of the Earth through a Volcano and cools and solidifies. It will cool fast if it comes out (extrusive) and will have small or no crystals, eg, Basalt. Slow cooling inside the crust (intrusive) will produce larger crystals, eg, granite.

Basalt Fast cooling Magma. Small crystals. Dark coloured.

Granite

Magma cools slowly, often in cracks in the crust. Gives time for mineral crystals to form in the rocks. Pretty.

Metamorphic Rocks are pushed down near the mantle or under mountains. Intense heat from the mantle and/or pressure from above cause the rocks to change. They become very hard and pretty. Eg, Pounamu (jade), Marble.

Pounamu Metamorphic. Formed by heat and pressure.

Marble Metamorphic. Formed in the same way as jade. Formed from limestone. Often used to make benches and ornaments.

Marble

The rock cycle – how rocks change