The Rock Cycle

What is the Rock Cycle ?

The Rock Cycle explains how rocks and natural processes are related weathering Sedimentary Metamorphic melting pressure, heat Igneous

Rock Cycle A series of events involving the formation, alteration, destruction, and reformation of rocks as a result of natural processes.

We will use the graphic seen in the background to help represent the Rock Cycle. There are many ways to show the various relationships between the rocks and the related natural processes.

Before we look at the Rock Cycle in detail, let’s review some basic information …

The three rock types are … The Rock Cycle involves the recognition of three main classes of rocks. The three rock types are …

CEMETERY Sedimentary Rocks Metamorphic Rocks METABOLIC Igneous Rocks INGENIOUS Right?

The mantle, crust and surface of the earth can be thought of as a giant recycling machine; rocks redistributed and transformed from one rock type to another. S M I

Now that we better understand the largest components of geology … lets move to some of the smallest components of geology …

There is a hierarchy to the elements of Geology Atoms make up elements. There is a hierarchy to the elements of Geology Elements combine to form the natural compounds. Natural compounds and elements combine to form minerals. . Minerals make up rocks. Rocks make up the Earth.

Only eight elements make up over 98% of the earth’s crust! Na Mg Al Si K Ca Fe Only eight elements make up over 98% of the earth’s crust!

What are Minerals? How can we tell what they are? Atoms make up elements. There is a hierarchy to the elements of Geology Elements combine to form the natural compounds. Natural compounds and elements combine to form minerals. . Minerals make up rocks. What are Minerals? How can we tell what they are? Rocks make up the Earth.

The identifiable characteristics of minerals are naturally occurring compounds having an orderly internal structure and a specific chemical composition, crystalline form and physical properties of a solid

Minerals combine to form Rocks

Some rocks are made up of just one mineral - like the sedimentary rock salt (made up of the mineral halite) that is mined in VA, MI, and NY. Other rocks are made up of many minerals - like the igneous rock granite and the metamorphic rock gneiss, found in western NC.

Now that some of the basics have been covered, lets consider some of the details about the Rock Cycle

The Rock Cycle weathering Sedimentary Metamorphic Igneous Rocks are weathered, eroded, transported, deposited,and lithified to form sedimentary rocks

Becoming a SEDIMENTARY ROCK … The igneous rock granite can be physically weathered to produce clay and sand. These sediments can be transported deposited and lithified to form sedimentary rocks. Clay can become shale Sand can become sandstone.

Becoming a SEDIMENTARY ROCK … The metamorphic rock gneiss can be physically weathered to produce clay and sand. These sediments can be transported deposited and lithified to form sedimentary rocks. Clay can become shale Sand can become sandstone.

Becoming a SEDIMENTARY ROCK … Sedimentary rocks can be physically weathered to produce sediments that can become other sedimentary rocks.

2KAlSi3O8+ 2H+ + H2O  Al2Si2O5(OH)4+ 2K+ + 4SiO2 Becoming a SEDIMENTARY ROCK … H2O + CO2  H2CO3 2KAlSi3O8+ 2H+ + H2O  Al2Si2O5(OH)4+ 2K+ + 4SiO2 Chemical weathering dissolves the minerals in rocks. The resulting dissolved compounds could form evaporites like rock salt or rock gypsum or chemical precipitates like some kinds of limestones. What forms depends upon composition and depositional environment factors.

Sedimentary rocks include: sandstone, shale, limestone, rock salt, and rock gypsum.

As the ice advances it can scour the bedrock and move a lot of material. When the ice retreats, sediments are deposited and new set of landforms exist.

Glacial deposits are much younger than the bedrock on which they are resting.

The Rock Cycle melting Sedimentary Metamorphic Igneous Igneous Rocks form from magma below the surface or from lava extruded at the surface

Becoming an IGNEOUS ROCK … Any existing rock – igneous, metamorphic or sedimentary – will melt if it is subjected to enough heat and/or pressure. When liquid magma cools to a solid it becomes an igneous rock. The kind of igneous rock formed depends on what was melted and how it cooled. Igneous rocks are classified based on their mineral composition and texture.

Igneous rocks include: granite basalt rhyolite granodiorite pegmatite

The Rock Cycle pressure, heat Sedimentary Metamorphic Igneous Pressure,heat, and fluids cause existing rocks or sediments to become metamorphic rocks

Becoming a METAMORPHIC ROCK … If the sedimentary rock limestone or dolomite is metamorphosed it can become the metamorphic rock marble. If the sedimentary rock sandstone is metamorphosed it can become the metamorphic rock quartzite. If the sedimentary rock shale is metamorphosed it can become the metamorphic rock slate.

Becoming a METAMORPHIC ROCK … If the metamorphic rock slate is metamorphosed it can become the metamorphic rock phyllite If the metamorphic rock phyllite is metamorphosed it can become the metamorphic rock schist. If the metamorphic rock schist is metamorphosed it can become the metamorphic rock gneiss.

DEQ GSD - The Rock Cycle in Michigan - February 2001 weathering melting pressure, heat Sedimentary Metamorphic Igneous The Rock Cycle does not go in just one direction. Any given rock can go through any part of the cycle any number of times. DEQ GSD - The Rock Cycle in Michigan - February 2001

DEQ GSD - The Rock Cycle in Michigan - February 2001 weathering melting pressure, heat Sedimentary Metamorphic Igneous I hope you better understand the Rock Cycle and what it means. DEQ GSD - The Rock Cycle in Michigan - February 2001