Rocks Naturally occurring Solid substance Made of minerals 3 types of rocks Sedimentary Igneous Metamorphic
Rocks can be compared to cookies
Sedimentary rocks Formed from sediment (small particles of rock) pressed and cemented together over millions of years. Limestone made from particles of calcite (fizzed with acid) Sandstone: made from sand size particles; rough Shale: made from very small particles, smooth and black.
Sedimentary rock forms layers Remember the Grand Canyon activity? Which layer is the oldest?
Igneous Rocks Formed when molten rock cools and hardens – Magma is molten rock below the surface – Lava is molten rock above the surface
Extrusive igneous rocks Form above the surface Lava cools quickly Small grains Intrusive igneous rocks Form below the surface Magma cools slowly Large grains
Granite Igneous rock with large grains/crystals Formed when magma cools and hardens Is it intrusive or extrusive?
Basalt Formed when flowing lava cools and hardens Small grains Is it intrusive or extrusive?
Pumice Formed when bubbling lava cools and hardens Small grains with air holes from bubbles; igneous rocks with air holes are called vesiculated. Intrusive or extrusive?
Obsidian (Volcanic glass) Formed when lava cools and hardens very quickly Very tiny grains or no grains at all Intrusive or extrusive?
Metamorphic Rock Formed when extreme heat and pressure below the surface of the earth change existing rocks into another rock. PARENT ROCKMETAMORPHIC ROCK
What changes? The minerals may change to another mineral by chemical reactions. The arrangement of minerals may change; they might line up and form bands; this is called foliation.
Marble A metamorphic rock that comes from limestone The calcite has formed larger crystals Marble reacts to acid..
Gneiss (“nice”) Formed from granite or shale The minerals become arranged in bands.
Quartzite Forms from sandstone The minerals from the sand (quartz) grow together to form bigger crystals.
Slate Formed from shale that is compressed over a long period of time.
Rock Cycle