Download presentation
Presentation is loading. Please wait.
1
Chapter 3 Geology of the Ocean
2
Key Concepts The world ocean has four main basins: the Atlantic, Pacific, Indian, and Arctic. Life first evolved in the ocean. The earth’s crust is composed of moving plates. New seafloor is produced at ocean ridges and old seafloor is removed at ocean trenches.
3
Key Concepts The ocean floor has topographical features similar to those found on continents. The seafloor is composed of sediments derived from living as well as nonliving sources. Latitude and longitude determinations are particularly necessary for precisely locating positions in the open sea, where there are no features at the surface.
4
World Ocean Primitive earth and formation of the ocean
early earth thought to be composed of silicon compounds, iron, magnesium oxide, and other elements gradually, the earth heated, causing melting and separation of elements water vapor locked within minerals worked its way to the surface, where it cooled, condensed, and formed the ocean
5
World Ocean Ocean and the origin of life
atmosphere formed by gases escaping from deep within the planet free oxygen formed oxides, oxygen did not accumulate until evolution of modern photosynthesis Stanley Miller’s apparatus demonstrated that simple organic compounds could have been formed under conditions present on primitive earth
6
Figure 3-1 MILLER’S APPARATUS.
7
Figure 3-2 OLDEST KNOWN FOSSILS.
8
World Ocean The ocean today 4 major ocean basins:
Pacific Atlantic Indian Arctic Pacific Ocean - largest Arctic Ocean - smallest Seas - smaller than ocean, essentially landlocked
9
Figure 3-3 THE WORLD OCEAN.
10
Table 3-1 Characteristics of Major Ocean Basins
11
Continental Drift Layers of the earth
Inner core: solid, iron- and nickel-rich Outer core: liquid (same composition) Mantle: thickest layer with greatest mass, mainly magnesium-iron silicates Crust: thinnest and coolest, outermost Lithosphere: crust and upper mantle Asthenosphere: region of mantle below the crust
12
Figure 3-4 (upper) COMPOSITION OF THE EARTH.
13
Figure 3-4 (lower) COMPOSITION OF THE EARTH.
14
Continental Drift Moving continents Alfred Wegener
Continents fit together like pieces of jigsaw puzzle One supercontinent - Pangaea Laurasia and Gondwanaland
15
Figure 3-5 THE SUPERCONTINENT PANGEA.
16
Continental Drift Forces that drive continental movement
magma moves by convection currents midocean ridges - form along cracks where magma breaks through the crust at subduction zones, old crust sinks into the mantle where it is recycled seafloor spreading causes continental drift
17
Figure 3-6 FORMATION OF OCEANIC CRUST AND MOUNTAINS.
18
Figure 3-7 SEAFLOOR SPREADING AND CONTINENTAL DRIFT.
19
Continental Drift Evidence for continental drift
fit of continental boundaries earthquakes seafloor temperatures highest near ridges age of crust, as determined by samples drilled from the ocean bottom, increases with distance from a ridge
20
Figure 3-8 (upper) EARTHQUAKE ZONES AND TECTONIC PLATES.
21
Figure 3-8 (lower) EARTHQUAKE ZONES AND TECTONIC PLATES.
22
Figure 3-A MAGNETOMETER DATA.
23
Continental Drift Theory of plate tectonics
lithosphere is viewed as a series of rigid plates separated by earthquake belts divergent plate boundaries: located at midocean ridges where plates move apart convergent plate boundaries: located at trenches where plates move toward each other faults: regions where plates move past each other (e.g. transform faults) rift zones: where lithosphere splits
24
Continental Drift Rift (Deep Sea Vent) Communities
depend on specialized environments found at divergence zones of the ocean floor first discovered by Robert Ballard and J.F. Grassle in 1977, in the Galápagos Rift primary producers are chemosynthetic bacteria
25
Ocean Bottom Bathygraphic features Continental margins
Geological features similar to land: mountain ranges; canyons, valleys; great expanses Continental margins continental shelf, continental slope, and shelf break Submarine canyons Continental Rises Shaping Continental Shelves
26
Figure 3-11 CONTINENTAL SHELF.
27
Figure 3-12 (a) FORMATION OF CONTINENTAL SHELF.
28
Figure. 3-12 (b) FORMATION OF CONTINENTAL SHELF.
29
Figure 3-12 (c) FORMATION OF CONTINENTAL SHELF.
30
Figure 3-12 (d) FORMATION OF CONTINENTAL SHELF.
31
Coral reef, volcano, or island Water-deposited sediment
Sediment from beach erosion Sediments Continental rock Continent Wave-cut terrace Subsurface rock Coral reef, volcano, or island Water-deposited sediment River River sediment Continental rock Continental rock Stepped Art Fig. 3-12, p. 56
32
Ocean Bottom Ocean basin Life on the ocean floor
abyssal plains and hills seamounts ridges and rises trenches and island arcs Life on the ocean floor continental shelves are highly productive life on the abyssal plains is not abundant, no sunlight, no photosynthesis
33
Figure 3-13 LANDSCAPE OF THE OCEAN FLOOR.
34
Figure 3-14 OCEAN TRENCHES.
35
Table 3-2 Depth of Major Ocean Trenches
36
Composition of the Seafloor
Sediment—loose particles of inorganic and organic material Table 3-3 Composition of the Seafloor
37
Composition of the Seafloor
Hydrogenous sediments formed from seawater through a variety of chemical processes e.g. carbonates, phosphorites, manganese nodules Biogenous sediments formed from remains of living organisms mostly particles of corals, mollusk shells, shells of calcium carbonate or silicious planktonic organisms
38
Figure 3-15 BIOGENOUS SEDIMENTS.
39
Composition of the Seafloor
Terrigenous sediments produced from continental rocks by the actions of wind, water, freezing, thawing e.g. mud (clay + silt) Cosmogenous sediments iron-rich particles from outer space, land in the ocean and sink to the bottom
40
Figure 3-B AN AMPELISCID AMPHIPOD.
41
Finding Your Way around the Sea
Maps and charts Mercator projections bathymetric charts physiographic charts
42
Figure 3-16 MAP PROJECTIONS.
43
Figure 3-17 (a) BATHYMETRIC AND PHYSIOGRAPHIC CHARTS.
44
Figure 3-17 (b) BATHYMETRIC AND PHYSIOGRAPHIC CHARTS.
45
Finding Your Way around the Sea
Reference lines latitude longitude divisions of latitude and longitude
46
Figure 3-18 (a & b) LATITUDE AND LONGITUDE.
47
Figure 3-18 (c) LATITUDE AND LONGITUDE.
48
Finding Your Way around the Sea
Navigating the ocean principles of navigation a sextant was used to determine latitude based on the angle of the North Star with reference to the horizon longitude determined using chronometer
49
Figure 3-19 A SEXTANT.
50
Finding Your Way around the Sea
Navigating the ocean Global Positioning System (GPS) utilizes a system of satellites to determine position GPS measures the time needed to receive a signal from at least 3 satellites, and calculates position
51
Figure 3-20 THE EARTH’S TIME ZONES.
Similar presentations
