1. Rocks Building Blocks of the Earth’s Crust

2. Earth’s Layers

3. Chemical Composition of the Earth

4. Chemical Composition of the Earth’s Crust

5. Where the Rocks Are … The Crust

6. What Is a Rock? A rock is a mixture of minerals! What is a mineral? naturally occurring (not man-made) inorganic (not part of or a product of a (once) living organism ) solid (not made of liquid or gas) chemical compound with a definite chemical structure which gives it unique physical properties. Minerals are the building blocks of rocks.

7. Minerals minerals are compounds and compounds are composed of elements What are the most common elements in the crust? Oxygen (O) and Silicon (Si) the most common minerals are silicates (contain silicon and oxygen) –the most common silicate – quartz

8. Physical Properties of Minerals Hardness – what minerals can scratch it or be scratched by it Cleavage – how does it break … along planes? Streak – what does the powdered form look like Color – what colors are common Density – the mass of a given volume

9. Cleavage Calcite Halite

10. Rocks are divided into three major groups based on the methods of formation 1.Igneous rocks … from cooling lava or magma 2.Sedimentary rocks … from compacted sediments 3.Metamorphic rocks … meta (change) morphic (form) … rocks changed by extreme forces Rock Classification

11. Rocks Classification Rocks are further subdivided by –mineral composition what minerals are present in large quantities – texture what is the size of the mineral crystals (grains )

12. Igneous Rocks

13. Formed when molten rock cools and solidifies Magma Lava geollab.jmu.edu/Fichter/ IgnRx/Intrusiv.html

14. Volcano

15. Explosive vs Non-explosive

16. Magma vs. Lava Magma intrusive – below the surface gathers in large bodies called plutons may become lava cools slowly – forms large crystals Lava extrusive- above the surface expelled from a fissure or a volcano begins as magma cools rapidly – forms small or no crystals

17. Mineral Composition of Igneous Rocks Rich in silicates lots of feldspar, quartz, and other silicates lighter color more viscous – extrusives form steep volcanoes continental crust Poor in silicates lots of iron and magnesium rich minerals darker color less viscous – extrusives form large flows oceanic crust

18. Types of Common Igneous Rocks Extrusive (Volcanic) Intrusive (Plutonic) Rich in Silicates RhyoliteGranite Poor in Silicates BasaltGabbro

19. Igneous Rocks Rhyolite Gabbro Granite Basalt

20. Other Important Volcanics Pyroclastics – also called ejecta - thrown from the volcano – cool very quickly Obsidian – volcanic glass, a unique rock containing NO MINERALS Pumice – frothy volcanic glass

21. Sedimentary Rocks

22. formed from sediments (particles) that settle in great amounts and are cemented together under great pressure sedimentary rocks cover some 80% of the Earth's crust generally, the only type of rock to contain fossils

23. Sedimentary Rock Formation  Clastic – particles deposited by water, wind, or ice  Chemical – particles precipitate from solution  Organic – growth in place (eg, coral reefs)

24. Clastic –basic sedimentary rock. –accumulations of pieces of broken up (eroded) rock (clasts) which have piled up and been "lithified“ (turned to rock) by compaction and cementation

25. Queen’s Throne, Utah

26. Clastic Sediments formed from the erosion of other rocks most sediments are carried by rivers and are deposited in great amounts in the ocean under great pressure, these particles are cemented together classified by particle size

27. Clastic Particles and the Corresponding Rocks ParticleRock GravelConglomerate SandSandstone SiltSiltstone ClayClaystone Shale

28. Chemical –some form when water conditions change causing solids to precipitate out of solution –some form when standing water evaporates, leaving dissolved minerals behind

29. Limestone

30. Chemical Sediments DepositRock Calcium CarbonateLimestone Calcium MagnesiumDolomite Carbonate Sodium Chloride (Salt)Halite

31. Organic –accumulation of sedimentary debris caused by organic processes –shells, bones, and teeth (calcium) –these bits of calcium can pile up on the seafloor and accumulate into a thick enough layer to form an "organic" sedimentary rock –Limestone can form this way; also, lignite, bituminous coal

32. Metamorphic Rocks

33. metamorphics get their name from "meta" (change) and "morph" (form) the rock is moved into an environment in which the minerals which make up the rock become unstable and out of equilibrium with the new environmental conditions in most cases, this involves burial which leads to a rise in temperature and pressure

34. Metamorphic Rocks the metamorphic changes in the minerals always move in a direction designed to restore equilibrium any rock can become a metamorphic rock, including another metamorphic rock (can become a different metamorphic rock) a metamorphic rock exposed to too much heat will melt and become ??? common metamorphic rocks include slate, schist, gneiss, and marble

35. Metamorphic Rock - Gneiss www.nearctica.com/geology/ mineral/metamor.htm

36. Types of Metamorphism Regional areas of great amounts of pressure (during mountain-building) usually associated also with high temperatures Contact near magma chambers (plutons)

37. Types of Metamorphism Regional areas of great amounts of pressure (during mountain-building), usually associated also with high temperatures foliation of rocks present … pressure causes tabular minerals in the rock to grow parallel to each other and perpendicular to the direction of pressure (stress), generating a mineral alignment termed a foliation rocks often look folded or wavy

38. Foliation Slate

39. Metamorphic Rock www.aqd.nps.gov/grd/usgsnps/ rxmin/rock3.html

40. Types of Metamorphism Contact near magma chambers (plutons) rocks in “contact” or near-contact with the magma are baked new minerals are formed rocks do not conduct heat well (they are good insulators) so the zone of contact metamorphism is usually relatively narrow marble results from the contact metamorphism of limestone

41. Metamorphic Rock Marble

42. The Rock Cycle www.canadianrockhound.com/ junior/rock_cycle.html

43. http://www.ecomlink.org/MAP/Caribbean.gif

44. Many are extrusive volcanic islands –Eruption eventually above the surface of the water: Montserrat, Mt. Pelee, many others –Eruption below the surface and uplifted: St. John, St. Thomas Some are flat limestone islands –Aruba, Anegada, Anguilla, Bonaire, Curacao St. Croix is sedimentary, but has more complex origin Barbados is an accretionary wedge. Likely geological origins of Caribbean islands