T h e R o c k C y c l e

1. TheRockCycle Prepared by theMichigan Department of Environmental QualityOffice of Geological Survey

2. What is theRockCycle ?

3. The Rock Cycle explains how Rocks and Natural Processesare related weathering Sedimentary Metamorphic pressure, heat melting Igneous

4. A more traditional definition is: RockCycle is a sequence of events involving the formation, alteration, destruction, and reformation of rocks as a result of natural processes ... Glossary of Geology, Bates & Jackson, AGI

5. Wewill use the graphic seen in the background to helprepresent theRock Cycle. There are many ways to show the various relationships between the rocks and the related natural processes.

6. Before we look at theRock Cyclein detail, let’s review some basic information …

7. TheRock Cycleinvolves the recognition of three main classes of rocks. The three rock types are …

8. SedimentaryRocks MetamorphicRocks CEMETERY METABOLIC INGENIOUS IgneousRocks Right?

9. The eminent 18th century lawyer, doctor, gentleman farmerand founder of modern geoscience,James Hutton,developed the concept of theRock Cycleto show how rocksand natural, physical processes are interrelated.

10. The understanding of the world in the 18th century was different from today …

11. Hutton knew about solar energy and gravity at the surface. He did not know about from inside the earth. radioactiveheating Solar energy, gravity and radioactive heating are the major forces driving the Rock Cycle. As a result, the Rock Cyclewill be self-sustaining for thousands of millions of years.

12. How does an antique concept like the Rock Cycle hold up in light of contemporary data and scientific thinking?

13. Of special interest is Plate Tectonics.

14. The mantle, crust and surface of the earthcan be thought of as a giant recycling machine; rocks are neither created nor destroyed, but redistributed and transformed from one rock type to another. S M I

15. If you were to ask a geologist what the earth is … What do you think theresponse would be?

16. Diagram of the Interior of the Earth Crust0 to 40 km0°C Upper Mantle40 to 670 km1,000°C Lower Mantle670 to 2,890 km2,000°C Outer Core2,890 to 5,150 km3,700°C Inner Core5,150 to 6,370 km4,300°C

17. Now that we better understand the largest components of Geology … lets move to some of the smallest components of Geology …

18. Atomsmake upelements. There is a hierarchy to the elements of Geology Elementscombine to form the naturalcompounds. Naturalcompoundsandelementscombineto formminerals. . Mineralsmake uprocks. Rocksmake up theEarth.

19. Atomic Theory proposes that all matter is composed of the atoms of about 100 different chemical elements. It further proposes that chemical compounds are formed by the combination of the atoms of different chemical elements. Elements can be arranged, based on their identifiable properties, into the Periodic Table

20. O Na Mg Al Si K Ca Fe Only eight elements make up over 98%of the earth’s crust!

21. Atomsmake upelements. There is a hierarchy to the elements of Geology Elementscombine to form the naturalcompounds. Naturalcompoundsandelementscombineto formminerals. . Mineralsmake uprocks. What areMinerals? How can we tell what they are? Rocksmake up theEarth.

22. The identifiable characteristics of Mineralsare naturally occurring inorganic elements or compounds having an orderly internal structure and a characteristic chemical composition, crystal form and physical properties of a solid

23. Minerals combine to form Rocks

24. SomeRocksare made up of just one mineral - like the sedimentaryrock salt(made up of the mineral halite) that is mined near Detroit. OthersRocksare made up of many minerals - like the igneous rockgraniteand the metamorphic rockgneiss,found near Marquette.

25. Now that some of the basicshave been covered, letsconsider some of the details about the RockCycle

26. weathering Metamorphic Sedimentary Igneous TheRock Cycle Rocks are weathered,eroded,transported,deposited,and lithified to formsedimentary rocks

27. Becoming a SEDIMENTARY ROCK … The igneousrock granite canbe physically weathered to produce clay and sand. These sediments can be transported deposited and lithified to form sedimentary rocks. Clay can become shale Sand can become sandstone.

28. Becoming a SEDIMENTARYROCK … The metamorphicrock gneiss can be physically weathered to produce clay and sand. These sediments can be transported deposited and lithified to form sedimentary rocks. Clay can become shale Sand can become sandstone.

29. Becoming a SEDIMENTARYROCK … Sedimentary rocks can be physically weathered to produce sediments that can become other sedimentary rocks.

30. Becoming a SEDIMENTARYROCK … H2O + CO2 H2CO3 2KAlSi3O8+ 2H+ + H2O  Al2Si2O5(OH)4+ 2K+ + 4SiO2 Chemical weathering dissolves the minerals in rocks. The resulting dissolved compounds could form evaporites like rock salt or rock gypsum or chemical precipitates like some kinds of limestones. What forms depends upon composition and depositional environment factors.

31. Sedimentaryrocks include: sandstone,shale,limestone,rock salt,and rock gypsum.

32. As the ice advances it can scour the bedrock and move a lot of material. When the ice retreats,sediments are deposited and new set of landforms exist.

33. Glacial deposits are much younger than the bedrock on which they are resting.

34. Metamorphic Sedimentary melting Igneous TheRock Cycle Igneous Rocksform frommolten rockormagmain thesubsurface orfromlavaextruded at the surface

35. Becoming an IGNEOUS ROCK … Any existing rock – igneous, metamorphic or sedimentary - can be subjected to enough heat and or pressure causing it to melt. Molten rock is called magma. When magma cools to a solid it becomes an igneous rock. The kind of igneous rock formed depends on what was melted and how it cooled. Igneousrocks are classified based on their mineral composition and texture.

36. Igneous rocks include: granite basalt rhyolite granodiorite pegmatite

37. Metamorphic Sedimentary pressure, heat Igneous TheRock Cycle Pressure, heatand fluidscause preexistingrocks or sediments to becomemetamorphic rocks

38. Becoming a METAMORPHIC ROCK … If the igneous rock basalt is exposed to sufficient heat and or pressure it can be transformed into the metamorphic rock call metabasalt When the prefix meta is applied to a rock name that means that the original rock has been metamorphosed.

39. Becoming a METAMORPHIC ROCK … If the sedimentary rock limestone or dolomite is metamorphosed it can become the metamorphic rock marble. If the sedimentary rock sandstone is metamorphosed it can become the metamorphic rock quartzite. If the sedimentary rock shale is metamorphosed it can become the metamorphic rock slate.

40. Becoming a METAMORPHIC ROCK … If the metamorphic rock slate is metamorphosed it can become the metamorphic rock phyllite If the metamorphic rock phyllite is metamorphosed it can become the metamorphic rock schist. If the metamorphic rock schist is metamorphosed it can become the metamorphic rock gneiss.

41. weathering Metamorphic Sedimentary pressure, heat melting Igneous TheRock Cycle TheRock Cycledoes not go in just one direction. Any given rock can go through any part of the cycle any number of times. DEQ GSD - The Rock Cycle in Michigan - February 2001

42. weathering Metamorphic Sedimentary pressure, heat melting Igneous TheRock Cycle I hope you better understand the Rock Cycleand what it means. DEQ GSD - The Rock Cycle in Michigan - February 2001