Aim: What are the different types of rocks.

Objective: Ability classify the three basic types

Vocabulary: igneous, sedimentary, metamorphic, lava, magma, molten

Is this lava or magma, or both?

Molten rock is liquid rock.Do you think molten rock is hot ? Inside the earth it is called magmaWhen it reaches the outside: lava

Magma and/or lava forms igneous rock

Magma forms intrusive igneous rock

Lava forms extrusive igneous rock

What’s the difference?

Intrusive igneous rock – large crystals

•Granite

Intrusive igneous rock – large crystals

•Granite

•Occurs when magma cools slowly !

Extrusive igneous rock – small crystals

•Basalt

•Occurs when lava cools quickly

Igneous Rock

Intrusive Extrusive

Formed From Magam lava

Cools Slowly quickly

Results Large crystals Small crystals

Granite Basalt

Sedimentary rocks “show” layers

Formation

 Sedimentary rocks are formed from pebbles, sand, silt, or clay

Also formed from the shells or microscopic skeletons of dead sea organisms (1-celled)  

Streams carry the tiny eroded fragments of stone and spread them out over a flood plain.

Layers of these materials are built up over millions of years.  

The layers of sediment turn into rock strata.

Formation Sedimentary rocks are formed when eroded

fragments of old rocks and dead organisms settle (usually in seas or rivers) to form a sediment. Over millions of years, layers of sediment build up and are buried one on top of the other.

They are compressed, and their weight squeezes out the water.

Eventually they become bonded together to form sedimentary rocks.

FormationWhat are they like?

Sedimentary rocks have a layered appearance. They may contain fossil remains of animals and plants that were trapped as the rocks formed. These fossils can be used to date the rock.

Limestone, sandstone and mudstone are examples of sedimentary rocks.

 

A stream is carrying silt and clay into a large lake or sea.

Millions of years have gone by and there are many layers of deposited sediment now. Some of the sediment granules have been cemented together by minerals that were dissolved in the water.  They have turned into layers of rock

Millions of years later, the water is no longer there, Sedimentary rocks is exposed to the atmosphere on Earth.

Millions of years later, pressure from inside the Earth may cause the layers of rock to rise or fall

BTW: Which layer of rock is the oldest?

Millions of years later, pressure from inside the Earth may cause the layers of rock to rise or fall

BTW: Which layer of rock is the oldest?

Sometimes there is an earthquake or other fault which make the layers “disjoint”

Sometimes the older sedimentary layers are covered by new volcanic activity: magma or lava

Metamorphic Rocks

Sometimes existing rock is subject to extreme heat or pressure –

This changes the rock to a new classification called metamorphic rock

Metamorphic formation may occurs in areas where existing layers of rock comes in contacts with underground magma

Metamorphic formation may form in areas where existing layers of rock comes under great pressure because they are under so many other layers of rock.

Rock Cycle

Rocks can and do change from one form to another.

The Rock Cycle is a model of these changes which may occur over millions of year !