Name NOTES What is a Rock? o Naturally-occurring mixtures of, mineraloids, glass or organic matter. o Rocks are divided into 3 groups based on how they were formed: What is the difference between a rock and a mineral? Rocks are made up of minerals. Once a rock is formed, does it stay the same rock forever?! Rocks are by many processes, such as weathering, erosion, compaction, cementation, melting, and cooling Rocks can change to and from the three types What is the process through which rocks change? The Rock Cycle earth materials change back and forth among the different types of rocks No set path a rock takes to become another kind of rock IGNEOUS Weathering, Erosion, Compaction, Cementation Recrystallization Melting, Solidification Melting, Solidification Recrystallization SEDIMENTARY How are rocks redistributed? Weathering, Erosion, Compaction, Cementation METAMORPHIC
The core, mantle, & crust are one giant rock ***Watch the Rock Cycle by Brainpop and answer the questions. 1. What do igneous rocks form from? 2. What kind of rock is sandstone? 3. What are metamorphic rocks formed by? How can Starbursts represent the Rock Cycle? Which rock form does your stacked Starbursts represent? Now press your sedimentary rock in the palm of your hands for at least 2 minutes (do not twist) What do you observe? Which type of rock does this represent? Watch as the new Starburst rock is melted. What do you notice? What kind of rock is it now? Ignis = Latin for Formed from the cooling of either The most type of rock Classified according to their and ORIGIN Where rocks are formed o Below ground = from magma (intrusive igneous rock) Usually have crystal grains (they cooled ) Some have large & small crystals (called porphyritic) o Above ground = from lava (extrusive igneous rock) Usually have crystals (they cooled too ) Practice Classifying Igneous Rocks as intrusive or extrusive Take out & classify these rocks from your kits. Examine their crystals. Classify them (circle your choice) and tell why you did. #5 Peridotite: Intrusive or Extrusive? Why? #4 Granite: Intrusive or Extrusive? Why? #11 Porphyry: Intrusive or Extrusive? Why? #12 Obsidian: Intrusive or Extrusive? Why? COMPOSITION What kind of substances the rocks are made of
Basaltic Igneous Rocks made from lava/magma that is low in, rich in iron and magnesium. Rocks are -colored. Granitic Igneous Rocks made from magma/lava in silica and oxygen. Rocks are -colored. Andesitic Igneous Rocks have a composition between basaltic and. Practice Classifying Igneous Rocks according to their composition: Circle your choices: #1: Diorite My Guess: B/G/A Actual composition: B/G/A #8: Basalt My Guess: B/G/A Actual composition: B/G/A #4: Granite My Guess: B/G/A Actual composition: B/G/A o Formed from (rock fragments, mineral grains, animal & plant remains) that are pressed or cemented together or when sediments out of a solution. o These sediments are moved by wind, water, ice or gravity. o Sedimentary rocks represent % of the Earth s crust, but they cover % of the Earth s surface. o Sedimentary rocks are -carrying rocks. What turns sediments into solid rock? Water or wind and sediment (erosion & deposition) The heavy sediments on the layers beneath (compaction) Dissolved minerals flow between the particles and them together (cementation) How were most of the sedimentary rocks in the Puget Sound area deposited? o Glaciers about years ago. How can sedimentary layers help us understand the age of fossils? o As sedimentary rocks are deposited, they form horizontal layers
o Scientists know that the layers on (and the fossils in the top layer) are than the fossils in lower layers. 3 Types of Sedimentary Rocks: 1) Clastic (also called Detrial) made of pieces of other rocks 2) Organic remains of are deposited in thick layers Examples Fossil rich limestone is made from the shells of ocean animals; used to make chalk 3) Chemical dissolved in lakes, seas, or underground water Examples -- made when calcite mineral precipitates from sea water made from evaporation of sea waters o Rocks that have changed due to intense and o Meta means and morphosis means in Greek o Igneous, sedimentary and other metamorphic rocks can change to become metamorphic rocks What occurs in the Earth to change these rocks? from overlying rock layers High, but not enough to melt the rock Rocks may be or bent or atoms may be exchanged to form new minerals. *You can think of metamorphic rocks as a squished peanut butter & jelly sandwich in your lunch. How are metamorphic rocks classified? Foliated mineral grains are flattened and line up in parallel Example: gneiss formed from rearrangement of minerals in granite into bands Non-Foliated bands are formed Example: marble formed from limestone
Where do metamorphic rocks usually form? o Where magma relatively cool rock o Near plates (near mountain ranges) o Places that are covered miles thick with other rock causing pressure o When hot water intrudes rock o Where a strikes Earth (rare) o Where lightning bolts strike rocks (rare)