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Do Now What was the period in history known as when scientific inquiry came to a stand still? What was the period in history known as when scientific inquiry came to a stand still? Who was the first sea captain to have a naturalist among his crew? Who was the first sea captain to have a naturalist among his crew? Why was the challenger expedition so important to the field of marine science? Why was the challenger expedition so important to the field of marine science?

Objective Finish up history- (Friday) Finish up history- (Friday) SWBAT: Describe major topographic features present on the sea floor. SWBAT: Describe major topographic features present on the sea floor.

Chapter Two The Sea Floor

Modern Marine Biology Today, several marine biology research stations exist in locations around the world. Today, several marine biology research stations exist in locations around the world. In the United States, several facilities are considered to be among the best in the world, including: In the United States, several facilities are considered to be among the best in the world, including: –Woods Hole Marine Biological Lab, MA –Scripps Institute - La Jolla, CA –Friday Harbor Labs, WA

Important Tools of the Trade Remote sensing – satellites are used to view large expanses of ocean at the ocean’s surface only. Remote sensing – satellites are used to view large expanses of ocean at the ocean’s surface only. Sonar – used to map seafloor depths and formations. Sonar – used to map seafloor depths and formations. Scuba – used for direct human exploration of oceanic environment for longer periods and at deeper depths than would otherwise be available to man. Scuba – used for direct human exploration of oceanic environment for longer periods and at deeper depths than would otherwise be available to man. Remotely operated vehicles (ROV’s) – allows for direct exploration of marine environment when scuba is not an option; these ROV’s can be manned (such as Alvin mentioned in chapter 1 readings) or unmanned. Remotely operated vehicles (ROV’s) – allows for direct exploration of marine environment when scuba is not an option; these ROV’s can be manned (such as Alvin mentioned in chapter 1 readings) or unmanned.

Important Tools of the Trade Research vessels – these floating laboratories allow oceanographers and marine biologists to explore the marine environments for weeks, months or even years without returning to a land-based facility. Research vessels – these floating laboratories allow oceanographers and marine biologists to explore the marine environments for weeks, months or even years without returning to a land-based facility. Underwater Research Station - Aquarius – underwater research and residential facility located in the Florida Keys. This underwater lab is located approx. 60 feet underwater and allows researchers to stay at this depth for days or weeks without surfacing (eating, sleeping, laboratory work, etc. – everything is done here (think of it like an airtight Winnebago!) Read more about Aquarius at Underwater Research Station - Aquarius – underwater research and residential facility located in the Florida Keys. This underwater lab is located approx. 60 feet underwater and allows researchers to stay at this depth for days or weeks without surfacing (eating, sleeping, laboratory work, etc. – everything is done here (think of it like an airtight Winnebago!) Read more about Aquarius at

Geography of the Ocean Basins The world ocean is the predominant feature on the Earth in total area. The world ocean is the predominant feature on the Earth in total area. In the Northern Hemisphere, 61% of the total area is ocean. In the Northern Hemisphere, 61% of the total area is ocean. In the Southern Hemisphere, about 80% of the total area is ocean. In the Southern Hemisphere, about 80% of the total area is ocean. The world ocean is divided into four large basins: Pacific, Atlantic, Indian and Arctic. The world ocean is divided into four large basins: Pacific, Atlantic, Indian and Arctic.

Ocean Basins Which is the largest? Which is the largest? Which is the shallowest? Which is the shallowest? Which two are similar in size? Which two are similar in size? Which is the deepest? Which is the deepest?

Structure of the Earth The Earth is thought to have originated 4.5 billion years ago from dust accumulated from the Big Bang The Earth is thought to have originated 4.5 billion years ago from dust accumulated from the Big Bang Due to heat associated with these events, the early Earth was likely molten Due to heat associated with these events, the early Earth was likely molten This allowed materials to settle by density as the materials cooled This allowed materials to settle by density as the materials cooled

Structure of the Earth Heavier materials settled deep in the Earth Heavier materials settled deep in the Earth Lighter components formed a thin crust Lighter components formed a thin crust Eventually, the Earth’s oceans and atmosphere began to form Eventually, the Earth’s oceans and atmosphere began to form Earth’s location relative to the sun allows for water to stay liquid – an essential element to sustain life Earth’s location relative to the sun allows for water to stay liquid – an essential element to sustain life

Internal Structure of the Earth Core – innermost layer; solid inner core and liquid outer core; iron-rich. Core – innermost layer; solid inner core and liquid outer core; iron-rich. Mantle – middle layer; semi-plastic composition. Mantle – middle layer; semi-plastic composition. Crust – outermost layer; thinnest portion of the Earth. Crust – outermost layer; thinnest portion of the Earth.

Continental versus Oceanic Crust Oceanic crust – made up of dark-colored mineral, basalt; denser than continental crust; younger than continental crust (less than 200 million years old). Oceanic crust – made up of dark-colored mineral, basalt; denser than continental crust; younger than continental crust (less than 200 million years old). Continental crust – light-colored granite construction mainly; less dense; some crust as old as 3.8 billion years old. Continental crust – light-colored granite construction mainly; less dense; some crust as old as 3.8 billion years old.

Check for understanding Which type of crust is the thinnest? Which type of crust is the thinnest? Which type of crust is the oldest? Which type of crust is the oldest? What 2 layers of the earth make up the lithosphere? What 2 layers of the earth make up the lithosphere?

Continental Drift Proposed in 1912 by Alfred Wegner Proposed in 1912 by Alfred Wegner He suggested that all continents had been joined in a single supercontinent which he named Pangaea. He suggested that all continents had been joined in a single supercontinent which he named Pangaea. He proposed that Pangaea began breaking up 180 million years ago. He proposed that Pangaea began breaking up 180 million years ago. At the time, his proposal was not widely accepted by he could not explain HOW this occurred. At the time, his proposal was not widely accepted by he could not explain HOW this occurred.

Pieces of evidence to support Continental drift theory Pieces of evidence to support Continental drift theory 1) Landforms- The shore line of South America would fit with the Africa shore. Mnts. In South Africa line up with Mnts is Argentina. Coal fields in Brazil match with coal fields in Africa. 2) Fern-like fossils have been found in Africa, South America, Australia, India, Antarctica 3) Continents were exposed to different climates. (Example: deep scratches in rock showed that glaciers once covered South Africa. South Africa was closer to the South Pole.

Plate Tectonics Plate tectonics explains the “HOW” behind Wegner’s continental drift theory Plate tectonics explains the “HOW” behind Wegner’s continental drift theory The main features of plate tectonics are: The main features of plate tectonics are: –The Earth’s surface is covered by a series of crustal plates –The ocean floors are constantly moving; spreading in the center and sinking at the edges and being regenerated. –Convection currents beneath the plates assist movement –Heat from the mantle drives these currents

Topography on sea floor… Lxbfa4 Lxbfa4 Lxbfa4 Lxbfa4 Who was Harry Hess? Who was Harry Hess? What is the 12,000 mile Mnt range at the bottom of the ocean called? What is the 12,000 mile Mnt range at the bottom of the ocean called? How high is a Mnt at the bottom of the ocean? How high is a Mnt at the bottom of the ocean? What did Hess discover and what did he call his discover? What did Hess discover and what did he call his discover? Why doesn’t the earth grow in size? Why doesn’t the earth grow in size?

Evidence for Plate Tectonics Mid-Oceanic Ridges Mid-Oceanic Ridges –The mid-oceanic ridges rise from ocean floor – a chain of submarine volcanic mountains –at regular intervals, the ridge is displaced by faults in the Earth’s crust called transform faults –Very little sediment is located at the bottom near these ridges; sediment gets thicker away from the ridges signifying that the crust further from the ridge is older

Mid ocean ridge system Continuous chain of submarine volcanic Mnts Continuous chain of submarine volcanic Mnts Like the seam on a base ball (encircle the globe) Like the seam on a base ball (encircle the globe) Largest feature on the surface of our earth Largest feature on the surface of our earth

Trenches Deep depressions in the sea floor Deep depressions in the sea floor Common in the Pacific Common in the Pacific

Diagram Draw a picture and write a description Draw a picture and write a description Draw the sea floor include a ridge system and a trench. Draw the sea floor include a ridge system and a trench. Label where sea floor spreading occurs and where subduction occurs. Label where sea floor spreading occurs and where subduction occurs. Describe why the earth does not grow in size if sea floor spreading occurs. Describe why the earth does not grow in size if sea floor spreading occurs.

Critical thinking… Where would you find the oldest rocks on the sea floor? Where would you find the oldest rocks on the sea floor? Where would you find the youngest rocks on the sea floor? Where would you find the youngest rocks on the sea floor?

Vocab Pangea Pangea Basalt Basalt Lithosphere Lithosphere Mid-ocean ridge Mid-ocean ridge Trenches Trenches

Cool animation! Y1dmE Y1dmE Y1dmE Y1dmE Convection currents Convection currents

Exit Ticket

Evidence for Plate Tectonics Geomagnetic Anomalies: Geomagnetic Anomalies: –Occasionally, at random intervals, the Earth's magnetic field reverses. New rock formed from magma records the orientation of Earth's magnetic field at the time the magma cools. –Studies of the sea floor revealed "stripes" of alternating magnetization parallel to the mid- oceanic ridges. This is evidence for continuous formation of new rock at these ridges. As new rock forms, older rock is pushed farther away from the ridge, producing these patterns in the rock.

Evidence of Plate Tectonics Island Arcs Island Arcs –Chains of islands are found throughout the oceans, especially in the western Pacific. – These "Island arcs" are usually situated along deep sea trenches on the continental side of trenches. –These observations, along with many other studies of our planet, support the theory that underneath the Earth's crust is a layer of heated rock driving the creation of new ocean floor.

Marine Sediments Lithogenous sediments – derived from the break-down of rocks (weathering) Lithogenous sediments – derived from the break-down of rocks (weathering) Biogenous sediments – derived from the skeletons and shells of marine organisms Biogenous sediments – derived from the skeletons and shells of marine organisms

What Can We Learn from Sediments? Biogenous sediments (composed of microfossils) can reveal information from the past Biogenous sediments (composed of microfossils) can reveal information from the past Age of these sediments can be determined using carbon dating Age of these sediments can be determined using carbon dating Ocean temperature at the time the microfossils were formed can be determined by looking at the ratios of magnesium to calcium or by different ratios of oxygen isotopes Ocean temperature at the time the microfossils were formed can be determined by looking at the ratios of magnesium to calcium or by different ratios of oxygen isotopes

Continental Margins The margins of continents are boundaries between continental crust and oceanic crust The margins of continents are boundaries between continental crust and oceanic crust They generally consist of: They generally consist of: –Continental shelf (most landward) –Continental slope –Continental rise (most seaward)

The Continental Shelf Makes up about 8% of the ocean’s surface area Makes up about 8% of the ocean’s surface area However, it is biologically the richest area of the ocean However, it is biologically the richest area of the ocean The width varies from 1 km (0.6 mi) to 750 km (470 mi) The width varies from 1 km (0.6 mi) to 750 km (470 mi) Shelf ends at shelf break which occurs at a depth of 120 – 400 m ( ft) Shelf ends at shelf break which occurs at a depth of 120 – 400 m ( ft)

Continental Slope Can be thought of as the “edge” of a continent Can be thought of as the “edge” of a continent Begins at the shelf break and continues to deep sea floor Begins at the shelf break and continues to deep sea floor Much steeper than continental shelf and continental rise Much steeper than continental shelf and continental rise

Continental Rise Formed by sediments that have been pushed down from continental shelf and slope Formed by sediments that have been pushed down from continental shelf and slope It can be thought of as an underwater river delta (the river in this case is formed of sediments) It can be thought of as an underwater river delta (the river in this case is formed of sediments)

Types of Margins Passive margins: Passive margins: –Relatively inactive geologically –Characterized by flat, wide coastal plains, wide continental shelves and gradually sloping continental slopes –Example: East Coast of US

Types of Margins Active Margins: Active Margins: –Sites of more intense geologic activity including earthquakes, volcanoes and trenches –Characterized by steep, rocky shorelines, narrow continental shelves and steep continental slopes –Example: West Coast of US