What I will learn… (3-1) Describe how technologies help scientists map the ocean floor (3-2) Identify the following features on a sea floor map: continental shelf, continental slope, continental rise, trenches, plains, sea mounts, guyots, and mid-ocean ridges.

Think About It At its deepest point, the Puerto Rico Trench in the Atlantic Ocean is 28,231 feet (more than 5 miles deep). Because of the tremendous pressure, it is not possible for humans to personally explore this deep into the ocean.

Key Question How do scientists know what the bottom of the ocean floor looks like? How do they know how deep the oceans are? I think… because…

Investigating the Oceans Earth = Blue Planet 71% of planet covered with water 97% of that water is found in oceans Oceanography = Study of planet’s oceans

Ocean Geography Four major ocean basins Atlantic Pacific – largest and deepest Indian Arctic – smallest and most shallow

Tools for measuring the depth of the ocean floor Sonar Satellites Submersibles

Sonar = Sound Navigation and Ranging Sound waves sent to bottom of ocean Sound waves reflected back to a receiver Based on time it takes for wave to be reflected, the distance to ocean floor can be measured

Satellites Can measure the differences in the sea-surface height by bouncing microwaves off the ocean’s surface Underwater mountains cause sea surface level to be higher Canyons & trenches cause sea surface to be lower

Submersibles Underwater vessel that can be used for deep sea research Can be manned or unmanned (ROV) Carry scientific instruments to learn about ocean

The ocean floor is NOT flat! 3 Major Regions Continental Margins Ocean Basin Floor Mid-Ocean Ridge

A=Continental Shelf= Gently sloping area that extends from the shoreline

B=Continental Slope= Steep slope that marks boundary between continental crust and oceanic crust

C=Deep-Ocean Trench= Deepest part of the ocean; form when one plate moves underneath another plate

D=Mid-Ocean Ridge= Underwater mountain system; sea floor spreads apart; formed new ocean crust

E=Volcanic Island= Seamount that reaches the surface of the ocean

F=Seamount= Underwater volcano

G=Abyssal Plain= flat feature on bottom of ocean floor; most level places on Earth

Cape May, NJ Cape Roca, Portugal

Investigate Part B: Mapping the Ocean Floor Distance Depth

Direction #5 Color the ocean crust (sea floor) brown Color the water areas (not the ocean floor) on your graph: Depth between 0-110 light green Depth between 110-1100 light blue Depth between 1100 – ocean floor dark blue

Cape Roca, Portugal Cape Roca, Portugal Azores, Portugal Azores, Portugal Azores, Portugal Azores, Portugal Cape May, NJ Cape May, NJ Cape May, NJ Cape May, NJ Mid Atlantic Ridge Mid Atlantic Ridge Mid Atlantic Ridge

Continental Shelf Continental Shelf Continental Shelf Gently sloping area that extends from the shoreline Continental Shelf Gently sloping area that extends from the shoreline Continental Shelf Gently sloping area that extends from the shoreline Continental Shelf Gently sloping area that extends from the shoreline Abyssal Plain Deep extremely flat features Abyssal Plain Deep extremely flat features Abyssal Plain Deep extremely flat features Continental Slope Steep slope that marks boundary between continental crust and oceanic crust Continental Slope Steep slope that marks boundary between continental crust and oceanic crust Continental Slope Steep slope that marks boundary between continental crust and oceanic crust Continental Slope Steep slope that marks boundary between continental crust and oceanic crust Seamount Underwater volcanic peaks Seamount Underwater volcanic peaks

Azores, Portugal Cape May, NJ Cape Roca, Portugal Mid Atlantic Ridge

Continental Shelf Continental Slope Seamount Gently sloping area that extends from the shoreline Continental Slope Steep slope that marks boundary between continental crust and oceanic crust Seamount Underwater volcanic peaks