Rock Formation

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

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

Igneous rock, Sedimentary rock, and Metamorphic 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!

5. Igneous Rock Serve and Enjoy Igneous Rock Recipe 1. Take some Minerals & Gasses – Mix well Place in oven (2,000 C) Add Heat Energy & Melt Quartz + 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

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

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

“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 Conglomerate ***You can see lots of different stuff stuck together in these rocks!

Sedimentary Rock Recipe Weathering & Erosion Sedimentation & Deposition Compaction “Cementation” (stuck together) Sediments, minerals and rocks 1. Start at the Surface 2. Weather (Break Up) 3. Erode (Carry Away) 4. Sedimentation & Deposition Layers of sand and sediments Rain moves sand, dirt, and rocks down to the ocean 5. Compaction & Cementation 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 Notice the jaded rocks glued in this rock. This is from rocks that have been involved in flash floods. Take notice of small pieces of rock stuck together

The layers are going in this direction 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. Granite (Igneous) 2a. Add a mild amount of Heat (Not too hot) 2b. Squeeze to Foliate + Pressure + Pressure 3. Cool & (Re)-Crystallize Gneiss (foliated) + HEAT Note: Add more heat for Igneous Rock 4. Metamorphic Rock

Notice that the crystals have been squished into 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”

line up in mostly straight lines Granite=large, randomly Crystals line up in mostly straight lines Crystals are Random in their locations HEAT Pressure Granite=large, randomly located crystals Gneiss=smaller, lined up crystals becomes

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

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