3The Rock Cycle explains how Rocks and Natural Processes are related weatheringSedimentaryMetamorphicmeltingpressure, heatIgneous
4Glossary of Geology, Bates & Jackson, AGI A more traditional definition is:Rock Cycleis 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
5We will use the graphic seen in the background to help represent the Rock Cycle. There are many ways to show the various relationships between the rocks and the related natural processes.
6Before we look at the Rock Cycle in detail, let’s review some basic information …
7The three rock types are … The Rock Cycle involves the recognition of three main classes of rocks. All three types are found in Michigan.The three rock types are …
9The eminent 18th century lawyer, doctor, gentleman farmer and founder of modern geoscience, James Hutton, developed the concept of the Rock Cycle to show how rocks and natural, physical processes are interrelated.
10The understanding of the world in the 18th century was different from today …
11Hutton knew about solar energy and gravity at the surface Hutton knew about solar energy and gravity at the surface. He did not know about radioactive heating from inside the earth.Solar energy, gravity and radioactive heating are the major forces driving the Rock Cycle.As a result, the Rock Cycle will be self-sustaining for thousands of millions of years.
12How does an antique concept like the Rock Cycle hold up in light of contemporary data and scientific thinking?
14The mantle, crust and surface of the earth can be thought of as a giant recycling machine; rocks are neither created nor destroyed, but redistributed and transformed from one rock type to another.SMI
15If you were to ask a geologist what the earth is … What do you think the response would be?
16Diagram of the Interior of the Earth Crust 0 to 40 km 0°CUpper Mantle 40 to 670 km 1,000°CLower Mantle 670 to 2,890 km 2,000°COuter Core 2,890 to 5,150 km 3,700°CInner Core 5,150 to 6,370 km 4,300°C
17Now that we better understand the largest components of Geology … lets move to some of the smallest components of Geology …
18There is a hierarchy to the elements of Geology Atoms make up elements.There is a hierarchy to the elements of GeologyElements combine to form the natural compounds.Natural compounds and elements combine to form minerals..Minerals make up rocks.Rocks make up the Earth.
19Atomic 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
20Only eight elements make up over 98% of the earth’s crust! NaMgAlSiKCaFeOnly eight elements make up over 98% of the earth’s crust!
21What are Minerals? How can we tell what they are? Atoms make up elements.There is a hierarchy to the elements of GeologyElements combine to form the natural compounds.Natural compounds and elements combine to form minerals..Minerals make up rocks.What are Minerals? How can we tell what they are?Rocks make up the Earth.
22The identifiable characteristics of Minerals are naturally occurring inorganic elements or compoundshaving an orderly internal structureand a characteristic chemical composition,crystal form andphysical properties of a solid
25Some Rocks are made up of just one mineral - like the sedimentary rock salt (made up of the mineral halite) that is mined near Detroit.Others Rocks are made up of many minerals - like the igneous rock granite and the metamorphic rock gneiss, found near Marquette.
26Now that some of the basics have been covered, lets consider some of the details about the Rock Cycle
27The Rock CycleweatheringSedimentaryMetamorphicIgneousRocks are weathered, eroded, transported, deposited,and lithified to form sedimentary rocks
28Becoming a SEDIMENTARY ROCK … The igneous rock granite can be physically weathered to produce clay and sand.These sediments can be transported deposited and lithified to form sedimentary rocks.Clay can become shaleSand can become sandstone.
29Becoming a SEDIMENTARY ROCK … The metamorphic rock 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 shaleSand can become sandstone.
30Becoming a SEDIMENTARY ROCK … Sedimentary rocks can be physically weathered to produce sediments that can become other sedimentary rocks.
312KAlSi3O8+ 2H+ + H2O Al2Si2O5(OH)4+ 2K+ + 4SiO2 Becoming a SEDIMENTARY ROCK …H2O + CO2 H2CO32KAlSi3O8+ 2H+ + H2O Al2Si2O5(OH)4+ 2K+ + 4SiO2Chemical 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.
32In Michigan, sedimentary rocks make up the bedrock in the eastern northern, and southern peninsulas. Igneous and Metamorphic rocksSedimentary rocksGeneralized Bedrock Geology of Michigan
33Sedimentary rocks found in Michigan include: sandstone, shale, limestone, rock salt, and rock gypsum.Igneous and Metamorphic rocksSedimentary rocksGeneralized Bedrock Geology of Michigan
34As the ice advancesit can scour the bedrockand move a lot of material.When the ice retreats, sediments are depositedand new set of landforms exist.Michigan has been sculpted by four major glacial advances in last 1.8 million years during the Pleistocene Epoch.
35What will these sediments become? In Michigan, we live on top of a complex group of sediments that were deposited by the Glaciers.What will these sediments become?Generalized Quaternary Geology of Michigan
36Let’s look at the Devonian age sedimentary rocks in Michigan. Glacial depositsare much youngerthan thebedrock on which they are resting.Let’s look at the Devonian age sedimentary rocks in Michigan.
37The State Stone the ”Petoskey Stone” is a fossil coral (Hexagonaria percarinata) that lived in middle Devonianage seas some 375 million years ago. The rocks that formed in that environment are mostly limestones.
38Some Devonian life forms that existed were similar, while others were very different from what we know today.
39Do you know where, what is now Michigan, would be? Thismap ofthe globe showsone possible interpretation of the distribution of land and water during middle Devonian time.MIDo you know where, what is now Michigan, would be?
40Middle Devonian Rocks in Michigan Middle Devonian rocks are made up of many different sedimentary rock formations. These rocks are shown in blue.
41The Rock CyclemeltingSedimentaryMetamorphicIgneousIgneous Rocks form from molten rock or magma in the subsurface or from lava extruded at the surface
42Becoming 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.Igneous rocks are classified based on their mineral composition and texture.
43In Michigan, igneous rocks make up the bedrock in the western northern peninsula. Igneous and Metamorphic rocksSedimentary rocksGeneralized Bedrock Geology of Michigan
44Igneous rocks found in Michigan include: granitebasaltrhyolitegranodioritepegmatite
45The Rock Cyclepressure, heatSedimentaryMetamorphicIgneousPressure, heat and fluids cause preexisting rocks or sediments to become metamorphic rocks
46Becoming 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 metabasaltWhen the prefix meta is applied to a rock name that means that the original rock has been metamorphosed.
47Becoming 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.
48Becoming a METAMORPHIC ROCK … If the metamorphic rock slate is metamorphosed it can become the metamorphic rock phylliteIf 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.
49In Michigan, metamorphic rocks make up the bedrock in the western northern peninsula. Igneous and Metamorphic rocksSedimentary rocksGeneralized Bedrock Geology of MichiganDEQ GSD - The Rock Cycle in Michigan - February 2001
50Metamorphic rocks found in Michigan include: iron ore, schist, slate, quartzite, marble, and gneissIgneous and Metamorphic rocksSedimentary rocksGeneralized Bedrock Geology of MichiganDEQ GSD - The Rock Cycle in Michigan - February 2001
51DEQ GSD - The Rock Cycle in Michigan - February 2001 Michigan's State Gemstone is chlorastrolite a variety of pumpellyite. Also called greenstone and ‘Isle Royal Greenstone’. It is a metamorphic mineral found in altered igneous rocks (basalts, and diabases).DEQ GSD - The Rock Cycle in Michigan - February 2001
52DEQ GSD - The Rock Cycle in Michigan - February 2001 weatheringmeltingpressure, heatSedimentaryMetamorphicIgneousThe Rock Cycle does 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
53DEQ GSD - The Rock Cycle in Michigan - February 2001 weatheringmeltingpressure, heatSedimentaryMetamorphicIgneousI hope you better understand the Rock Cycle and what it means.Please any comments about this program to Steve Wilson: - thanksDEQ GSD - The Rock Cycle in Michigan - February 2001