Chapter 4, Section1 Rock: a mixture of minerals, volcanic glass, organic matter or other materials. – Display the physical and chemical properties of the minerals that make them up. – Now, could organic materials be rocks? Rock Cycle shows us that rocks constantly, yet slowly, change into different types. Page 91. Matter can never be created or destroyed, only changed (Law of Conservation of Matter)
Rock Cycle James Hutton – 1788 Must memorize the Rocks, Stages and Processes SOON! Insert Picture Here
What process forms: 1. Igneous rocks? Melting * and Cooling 2. Sedimentary rocks? Weathering, Erosion, * Compaction and Cementation 3. Metamorphic rocks? Heat and Pressure
Let’s Review: What is the model called that shows how rocks constantly, yet slowly, change into different types – The Rock Cycle (Page 91) Is there a definite pattern that the rock cycle follows? Name some. – BTW, My fav. Is S,I,I,M,S,I,I,S Who recognized/discovered the rock cycle? When? – James Hutton – 1788 - “The founder of modern geology” What are the three types of rocks? – Igneous, Sedimentary, Metamorphic What are the processes that form each type of rock? – Igneous?Metamorphic?Sedimentary?
Chapter 4, Section 2: Igneous rocks Form by lava or magma cooling – Both are melted rock, so what is the difference? Two main types of igneous rocks: – Intrusive - rocks formed slowly by magma inside the Earth - large crystals (grains) Name one: – Extrusive rocks formed quickly from lava outside of the Earth - - smaller crystal (grains) Name one:
Earth’s Heat The heat that produces magma comes from the radioactive decay of elements in the core of the Earth!!!
` Magma versus lava: Found where: Cools how fast: Crystal size: Forms what kind of igneous rock: Found where: Cools how fast: Crystal size: Forms what kind of igneous rock:
Three types of igneous rocks: based on the type of magma/lava – Basaltic: Dense and dark colored High in Iron and magnesium – Andesitic Medium – Granitic: Less dense and light colored High in Silicon and oxygen
What elements in a basaltic and granitic igneous rocks make the densities different? Basaltic: High in Iron and Magnesium, low in silicate minerals. Granitic: High in Oxygen and Silicon, low in iron and magnesium. VERY important to understand the chart on page 96!!!
Chart on p. 96 Questions – Be able to EXPLAIN – very similar to your quiz – Ooops, did I say that? – Which cooled faster? Diorite or Andesite? – What do Granite and Rhyolite have in common? – What makes them different? – Would you expect Gabbro or Granite to be more dense? – Based only on color, how could you know that Pumice is granitic and Scoria basaltic? – What elements are probably in Basalt? – NOW can you Friday’s question of which is more dense, basalt or granite? Remember that later this year.
Chapter 4 Section 3 Metamorphic rocks Meta – Greek for “form”; Morph – “to change” Rocks that are changed by: 1. heat and pressure (but were never melted) 2. the presence of hot fluids. Metamorphic rocks form from already existing Sed., Ig. or Met. rocks. The preexisting rock is called the parent rock.
Chapter 4, Section 2 Review What makes a metamorphic rock? (two things) Name a foliated rock, describe its appearance and its parent rock. Name a nonfoliated rock, describe its appearance and its parent rock.
Chapter 4, Section 4 Sedimentary rocks Most likely to contain fossils and organic material. Why? Sedimentary rocks are broken down into three types.
1. Detrital Sedimentary Rocks (Clastic) These rocks are made of previously existing rocks. The process that creates detrital sedimentary rocks is weathering, erosion, compaction, cementation – Order important!!! Examples include shale, siltstone, sandstone, conglomerate Named based on the sediment SIZE. (105)
The Sediment Size in rocks tells about the environment they were deposited, and the velocity of the water that deposited them. Sandstone – beaches or deserts Shale - deep, calm water Limestone - very deep ocean water Conglomerate – rivers (mixed velocities)
Stacked rocks Law of Superposition In an undisturbed layer of stacked rocks, the oldest rocks are found at the bottom and youngest at top.
2. Organic Sedimentary Rocks Organic rocks are made of once-living things – Examples of once living things are shells, dead plants, etc. Examples of organic rocks are: Coal Chalk Coquina
3. Chemical Sedimentary Rocks Formed from dissolved minerals in solution Examples include limestone (contains CaCO 3 ) and rock salt
Very important review: List Example of Each and which of the three types Organic Foliated Chemical: Intrusive Basaltic Nonfoliated Granitic: Detrital: Extrusive