Rocks and the Rock Cycle It Rocks! Rocks and the Rock Cycle

Just what are rocks? A rock is a mixture of minerals, rock fragments, volcanic glass, organic matter, or other natural materials. What do you see in this sample of pink granite?

What is the difference between a rock & a mineral? Minerals are solid, naturally occurring, inorganic, have a fixed composition and are made of one or more elements. Rocks are made of one or more minerals.

Let’s Compare… Solid Made of elements Must be inorganic Can be made from organic materials Must be inorganic Solid Can be made of lava/ magma Mixtures made of minerals Made of elements or compounds and must be chemically bonded Naturally occurring Have crystals Can be man made Can be formed from solutions

Rock Classifications Igneous Sedimentary Metamorphic

Igneous Rock Igneous is Greek and means ‘born of fire’ Igneous rock forms when magma, hot molten rock, cools and hardens Igneous rock can be intrusive or extrusive

Intrusive Igneous Rock Formed from magma cooled below the Earth’s surface Cools very slowly Forms mineral grains large enough to see with the unaided eye

Extrusive Igneous Rock Formed as lava cools on the surface of the Earth Cools quickly Exposed to air and water which can result in holes in the rock material Forms very fine (small) mineral grains.

Extrusive Igneous Rock Includes Volcanic Glass Lave cools very very quickly Few or no minerals grains form Atoms are not arranged in an orderly pattern

Sedimentary Rock Forms when sediments are pressed and cemented together Forms when minerals form from solutions Often form layers If undisturbed by nature, the oldest and first layer is the bottom layer

Sedimentary Rock Sediments are loose rock fragments, minerals grains, and bits of shell that have been moved by the wind, water, ice or gravity. Sediments form from the processes of weathering and erosion Compaction – occurs when pressure on the uppers layers of the sedimentary rock pushes down on the lower layers. Cementation – the process by which water and dissolved minerals move through open spaces and form a glue-like substance

Metamorphic Rock Metamorphosis – to change Rocks that have changed their chemical composition due to the presence of extreme heat and pressure or Rocks that have been subjected to hot watery fluids

Metamorphic Rock Can form from igneous, sedimentary or other metamorphic rock Can be foliated - mineral grains appear in parallel layers Can be nonfoliated – mineral grains do not align in layers

The What?...The Rock Cycle To show how rocks slowly change through time, scientists have created a model called the rock cycle. It shows the processes that form and change rocks. The rock cycle shows the three classifications of rock— igneous, metamorphic, and sedimentary—and the processes that form them.

The Rock Cycle explains how Rocks and Natural Processes are related weathering Sedimentary Metamorphic Is the rock cycle really this simple, neat and colorful? (NO) Created October 2, 2000, revised September 2001 melting pressure, heat Igneous

What is the law(principle) of conservation of matter? Law of conservation of matter states that matter cannot be created or destroyed. The changes that take place in the rock cycle never destroy or create matter. The elements are just redistributed in other forms.

Let’s Have Some Fun!!

More Fun with the Rock Cycle http://tinyurl.com/yzvw4k8 http://mrhardy.wikispaces.com/Rock+Cycle.swf http://tinyurl.com/8g2fr6f (Study Jams – really great site)

Prepared just for YOU, my 6th Grade Earth Science classes! Ms. Houston Austin Road Middle School