Rock Formation Main Concept Rocks are made from

Rock Formation

Main Concept: Rocks are made from Minerals • Rocks are nothing more than a mixture of ***All three minerals are different mineral crystals. combined in a Granite rock Granite Quartz (mineral) + Biotite (mineral) + Feldspar (mineral) = This is Continental Crust!!! (Rock)

Rocks are made from Minerals • Rocks are nothing more than a mixture of different mineral crystals. ***Both minerals combined make Basalt Pyroxene (mineral) + Olivine (mineral) = This is Oceanic Crust!!! Basalt (rock)

Rock Classification Geologists classify rocks into three major groups depending on how they are formed: Igneous rock, Sedimentary rock, and Metamorphic rock.

There are three types of rock: Igneous Rocks • Formed from cooled Lava and Magma As an Example: Liquid lava Frozen lava can become ***When the lava cools and turns into a solid, it can turn into Basalt!

Igneous Rock Recipe 1. Take some Minerals & Gasses – Mix well 2. Place in oven (2, 000 C) Quartz Add Heat Energy & Melt + Biotite + Feldspar 3. Change Rock to Liquid Phase (Magma) 4. Remove from heat, let it Cool & Crystallize (Intrusive/Extrusive) 5. Igneous Rock Serve and Enjoy Minerals + Heat 6

There are two types of Igneous Rock: 1)Intrusive • Formed inside the crust/mantle. • These types always have large visible crystals. (cooled slowly) • Ex: Granite and Gabbro This is a special kind of Granite called: “Pink Granite” ***Notice that both rocks have easy to see crystals

How Intrusive Igneous Rocks Form • When magma from below rises up, but does not make it to the surface, the minerals start to crystallize slowly and form large crystals. Volcanic Neck 8

There are two types of Igneous Rock: 2) Extrusive • Formed on top of the crust. • Small, hard to see crystals (cooled quickly) • Ex: Pumice, Obsidian ***No visible crystals in either rock

How Extrusive Igneous Rocks Form Blam! Ash, from Gasses, Minerals, • When magma below rises and Volcanic etc. don’t have punches through, theglass, minerals time to crystallize – therefore, they types of produce rocks with small crystals. Other rock are blasted out Lava Flow (Outside) Lava flows out and covers the surface Magma (inside) The lava will quickly cool into solid rock! 10

• “Granite” and “Rhyolite” form from the same type of cooled magma. • If the magma cools rapidly, smaller crystals form and “Rhyolite” rock is produced. • If the magma cools slowly, larger mineral crystals form and the type of rock known as “Granite” forms. Rhyolite: can you see crystals? There are no visible crystals! Granite: can you see crystals? There are lots of visible crystals!

There are three types of rock: Sedimentary Rock • Formed by sediments (pieces of rock, shells, and dead organisms) becoming “cemented” (stuck) together. Sandstone Coal Limestone ***You can see lots of different stuff stuck together in these rocks! Conglomerate

Sedimentary Rock Recipe Sediments, minerals and rocks 1. Start at the Surface 2. Weather (Break Up) Weathering & Erosion Sedimentation & Deposition 3. Erode (Carry Away) 4. Sedimentation & Deposition Layers of sand sediments Rain moves Compaction sand, dirt, and rocks down to the ocean 5. Compaction & Cementation “Cementation” (stuck together) Igneous rock Sediments worn away gather here!

Physical Properties of Sedimentary Rock rock that is glued to other rock Conglomerate Rock Notice the rounded rocks glued in this rock. This is from rocks that have been eroded in a river bed. Breccia Take notice of small pieces of rock stuck together Notice the jaded rocks glued in this rock. This is from rocks that have been 14 involved in flash floods.

How to identify: • Particles of shells/rocks – stuck together • Dull (not shiny) • Straight layers • Fossils (often) Sandstone: pieces of sand stuck together The layers are going in this direction can you see them?

Metamorphic Rocks • To “Morph” means to change it! “…more than meets the eye!” • Rocks that have changed after being buried DEEP underground. The heat and pressure from being deep underground changed the rocks. • They were once Igneous or Sedimentary rocks, but not anymore. • Has large, inter-grown crystals in thin “bands” (Foliated) or clusters (Non-Foliated).

Metamorphic Rock Recipe 1. Get some pre-formed rock – Igneous or Sedimentary will do & burry it deep underground. 2 a. Add a mild amount of Heat Granite (Igneous) 2 b. Squeeze to Foliate + Pressure (Not too hot) + Pressure 3. Cool & (Re)-Crystallize Note: Add more heat for Igneous Rock 4. Metamorphic Rock + HEAT Gneiss (foliated)

Foliation • Mineral crystals aligned in parallel layers. Notice that the crystals have been squished into mostly straight lines.

Pressure and Heat lead to Metamorphic Rocks The shoes represent the pressure caused by all the rock above the crystals The “playing cards” represent mineral crystals in a rock! Crystals are large Crystals have become “squished”

Crystals are Random in their locations Crystals line up in mostly straight lines HE AT es r P re u s Granite=large, randomly Gneiss=smaller, lined located crystals becomes up crystals

Foliated v. Non Foliated • Geologists classify metamorphic rocks according to the arrangement of the grains that make up the rocks. Foliated Non Foliated (curvy thin crystal lines - Gneiss) (No lines - Quartzite)

Examples of Metamorphic Rock: • Gneiss: • Schist: • Slate: Can you see all the straight layers of crystals?