Chapter 11: The Dynamic Planet The Pace of Change A. The Geologic Time Scale   II. Earth’s Structure and Internal Energy  A. The Earth’s Core  B. The Earth’s Mantle C. The Earth’s Crust III. The Geologic Cycle  A. Defined B. Types of Rock    IV. Plate Tectonics  

Pace of Change A. Geologic Time Scale Summary timeline of all Earth history. Relative versus absolute time. Uniformitarianism versus catastrophism. Six major extinctions of life forms Point out what percentages of time are in the precambrian and where we are now. Why is it organized with oldest on the bottom and youngest on the top? Figure 8.1

II. Earth’s Structure and Internal Energy Earth is estimated to be around 4.6 billion years old. Earth’s continental crust formed 4.0 billion years ago. Earths’ interior is sorted into concentric layers, each one distinct in either chemical composition or temperature. As Earth solidified, gravity sorted material by density. Heavier substances like iron gravitated slowly to its center, lighter elementsupwelled to the surface creating the crust of the earth.

II. Earth’s Structure and Internal Energy Seismic tomography: use of shock waves to measure the substances in the Earth. Figure 8.2

II. Earth’s Structure and Internal Energy Earth’s Core Inner core: solid iron, 5150 km beneath the Earth’s surface Outer core: molten metallic iron and lighter in density than the inner core, extends 2900 – 5150 km beneath Earth’s surface. Outer core generates 90% of Earth’s magnetic field that protects us from solar wind. A third of the Earth’s entire mass, but only a sixth of its volume lies in its dense core. Inner core is solid even though it is hot enough to melt because of the tremendous pressure

II. Earth’s Structure and Internal Energy B. Earth’s Mantle Begins 2900 km (1800 miles deep) up to 200 km beneath Earth’s surface Represents about 80% of Earth’s total volume Dominated by iron, magnesium, and silicates 670 km (415 miles) deep is where the upper and lower mantle separate. 670 km (415 miles) deep is where the upper and lower mantle separate.

II. Earth’s Structure and Internal Energy C. Earth’s Crust Begins about 200 km beneath Earth’s surface Composed of the lithosphere (includes continental and oceanic crust) The asthenosphere lies directly beneath the lithosphere Continental crust is granite, very low density (2.7g/cm3). Oceanic crust is basalt, higher density (3.0g/cm3)

II. Earth’s Structure and Internal Energy Structure of the Earth's crust and top most layer of the upper mantle. Beneath the lithosphere is the asthenosphere. This layer, which is also part of the upper mantle, extends to a depth of about 200 kilometers.

III. The Geologic Cycle Geologic Cycle: Refers to the vast cycling of rocks and minerals that occurs in the lithosphere. It encompasses the hydrologic cycle, the tectonic cycle, and the rock cycle. Factors that fuel the geologic cycle: Earth’s internal heat Solar energy from space Earth’s gravity

III. The Geologic Cycle

III. The Geologic Cycle A. Rock Cycle The rock cycle is a general model that describes how various geological processes create, modify, and influence rocks

III. The Geologic Cycle Rock types are identified by the processes that form them. Igneous: Rocks formed by the solidification of magma. (granite, basalt, rhyolite) Sedimentary: Rocks formed by the alteration and compression of old rock debris or organic sediments (sandstone, shale, limestone) Metamorphic: Rocks formed by alteration of existing rocks by intense heat or pressure. (marble, quartz, slate) Igneous (granite, basalt, rhyolite), form from magma – molten rock beneath the surface of the Earth Sedimentary rocks (sandstaone, shale, limestone, coal) Marble quartz

III. The Geologic Cycle A. The Rock Cycle Figure 11.6

III. The Geologic Cycle Igneous Rock Types

Sedimentary Rock Types

Sedimentary Rock Types

Metamorphic Rock Types

IV. Plate Tectonics   Continental landmasses migrated to their current position and continue to move about 2.4 inches per year. Continental drift: Idea that the Earth’s landmasses have migrated over the past 225 million years from a supercontinent called Pangaea to the present configuration. (essentially plate tectonics) 1912, Alfred Wegener publicly presented the idea of conitnental drift.

IV. Plate Tectonics   Mid- Mid-ocean ridges are the result of upwelling flows of magma from hot areas in the upper mantle and asthenosphere (possibly the lower mantle too).

IV. Plate Tectonics   Mid-

IV. Plate Tectonics A. Crustal Movements Sea floor spreading builds the mid-ocean ridges. * Note the subduction of oceanic crust underneath the continental crust. Nowhere does the seafloor exceed 208 million years of age. Note: subduction zones are points of volcanic and earthquake activity. Figure 8.13

IV. Plate Tectonics A. Crustal Movements Nowhere does the seafloor exceed 208 million years of age. Note: subduction zones are points of volcanic and earthquake activity.

IV. Plate Tectonics B. Relative Age of the Oceanic Crust Note the age of the ocean floor along the California coast. Dark areas indicate younger areas with increased activity compared to other regions of the world. Figure 8.15

IV. Plate Tectonics Oceanic Trenches Ocean trenches are long, narrow, steep-sided depressions found on the ocean floor that contain the greatest depths in the ocean (11,000 meters - western Pacific). There are 26 oceanic trenches in the world: 3 in the Atlantic Ocean, 1 in the Indian Ocean, and 22 in the Pacific Ocean (Figure 10p-3). Generally, the trenches mark the transition between continents and ocean basins, especially in the Pacific basin. Trenches are also the tectonic areas.

IV. Plate Tectonics C. Continents Adrift Panthalassa Sea became the Pacific Ocean Tethys Sea became the Meditteranean ocean Atlantic Ocean did not exist. The Appalachian Mountains in the eastern US and the Atlas Mountains of northwestern Africa were the same mountain range in figure b Figure c. New seafloor in grey, not Laurasia and Gondwana Figure d. note india is a separate continent and it traveled the farthest (10,000 km) Figure 8.16

IV. Plate Tectonics D. Earth’s Major Plates Boundary Types: Divergent Convergent Transform Earth’s crust is divded into 14 plates, of which about half are major and half are minor in terms of area. Arrow represents the direction and rate of movement Divergent: Nazca plate and the Pacific Plate, Great Rift Valley of East Africa Convergent: west coast of south and central america (creates the Andes mtns and volcanos) Transform: San Andreas Fault in California Consists of six great plates and nine lesser plates (you only need to know the great plates, OK?) The Pacific Plate occupies much of the Pacific Ocean and consists almost entirely of oceanic lithosphere, with a subduction zone along its western and northern boundary. The American Plate consists of continental lithospheres in both North and South America, as well as the western half of the Atlantic Ocean. Subduction on the west, spreading on the east. The Eurasian Plate consists mostly of continental lithosphere in Europe and nearly all of Asia. The African Plate has a central core of continental lithosphere centered on Africa. The Austral-Indian Plate is mostly oceanic lithosphere, but does contain continental lithosphere on India and Australia. The Antarctic Plate is elliptical, contains the continent Antarctica, and is enclosed by spreading plate boundaries. Figure 8.17

Earth’s crust is divded into 14 plates, of which about half are major and half are minor in terms of area. Arrow represents the direction and rate of movement Divergent: Nazca plate and the Pacific Plate, Great Rift Valley of East Africa Convergent: west coast of south and central america (creates the Andes mtns and volcanos) Transform: San Andreas Fault in California Consists of six great plates and nine lesser plates (you only need to know the great plates, OK?) The Pacific Plate occupies much of the Pacific Ocean and consists almost entirely of oceanic lithosphere, with a subduction zone along its western and northern boundary. The American Plate consists of continental lithospheres in both North and South America, as well as the western half of the Atlantic Ocean. Subduction on the west, spreading on the east. The Eurasian Plate consists mostly of continental lithosphere in Europe and nearly all of Asia. The African Plate has a central core of continental lithosphere centered on Africa. The Austral-Indian Plate is mostly oceanic lithosphere, but does contain continental lithosphere on India and Australia. The Antarctic Plate is elliptical, contains the continent Antarctica, and is enclosed by spreading plate boundaries.

Earth’s crust is divded into 14 plates, of which about half are major and half are minor in terms of area. Arrow represents the direction and rate of movement Divergent: Nazca plate and the Pacific Plate, Great Rift Valley of East Africa Convergent: west coast of south and central america (creates the Andes mtns and volcanos) Transform: San Andreas Fault in California Consists of six great plates and nine lesser plates (you only need to know the great plates, OK?) The Pacific Plate occupies much of the Pacific Ocean and consists almost entirely of oceanic lithosphere, with a subduction zone along its western and northern boundary. The American Plate consists of continental lithospheres in both North and South America, as well as the western half of the Atlantic Ocean. Subduction on the west, spreading on the east. The Eurasian Plate consists mostly of continental lithosphere in Europe and nearly all of Asia. The African Plate has a central core of continental lithosphere centered on Africa. The Austral-Indian Plate is mostly oceanic lithosphere, but does contain continental lithosphere on India and Australia. The Antarctic Plate is elliptical, contains the continent Antarctica, and is enclosed by spreading plate boundaries.

Earth’s crust is divded into 14 plates, of which about half are major and half are minor in terms of area. Arrow represents the direction and rate of movement Divergent: Nazca plate and the Pacific Plate, Great Rift Valley of East Africa Convergent: west coast of south and central america (creates the Andes mtns and volcanos) Transform: San Andreas Fault in California Consists of six great plates and nine lesser plates (you only need to know the great plates, OK?) The Pacific Plate occupies much of the Pacific Ocean and consists almost entirely of oceanic lithosphere, with a subduction zone along its western and northern boundary. The American Plate consists of continental lithospheres in both North and South America, as well as the western half of the Atlantic Ocean. Subduction on the west, spreading on the east. The Eurasian Plate consists mostly of continental lithosphere in Europe and nearly all of Asia. The African Plate has a central core of continental lithosphere centered on Africa. The Austral-Indian Plate is mostly oceanic lithosphere, but does contain continental lithosphere on India and Australia. The Antarctic Plate is elliptical, contains the continent Antarctica, and is enclosed by spreading plate boundaries.

Earth’s crust is divded into 14 plates, of which about half are major and half are minor in terms of area. Arrow represents the direction and rate of movement Divergent: Nazca plate and the Pacific Plate, Great Rift Valley of East Africa Convergent: west coast of south and central america (creates the Andes mtns and volcanos) Transform: San Andreas Fault in California Consists of six great plates and nine lesser plates (you only need to know the great plates, OK?) The Pacific Plate occupies much of the Pacific Ocean and consists almost entirely of oceanic lithosphere, with a subduction zone along its western and northern boundary. The American Plate consists of continental lithospheres in both North and South America, as well as the western half of the Atlantic Ocean. Subduction on the west, spreading on the east. The Eurasian Plate consists mostly of continental lithosphere in Europe and nearly all of Asia. The African Plate has a central core of continental lithosphere centered on Africa. The Austral-Indian Plate is mostly oceanic lithosphere, but does contain continental lithosphere on India and Australia. The Antarctic Plate is elliptical, contains the continent Antarctica, and is enclosed by spreading plate boundaries.

Figure 8.20