Fig. 7.1. A US Navy oceanographic survey ship using a multi-beam wide-angle sonar system to map the ocean floor
Image courtesy of US Navy, Wikipedia Commons
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Introduction to the Ocean Floor
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The ocean floor covers more than 70 percent of the planet’s surface. Like dry land, the ocean floor has various features including flat plains, sharp mountains, and rugged canyons (Fig. 7.1). However, the lowest point in the world ocean is much deeper than the highest point on land. The ocean floor is continually being formed and destroyed. To understand the ocean floor and its diverse features, it is important to learn about the formation of the earth and its geological history.
Ocean Literacy Principles
Principle 1: The earth has one big ocean with many features.
Ocean Literacy Fundamental Concept: An ocean basin’s size, shape and features (such as islands, trenches, mid-ocean ridges, rift valleys) vary due to the movement of Earth’s lithospheric plates. Earth’s highest peaks, deepest valleys and flattest vast plains are all in the ocean. (OLP 1b)
To build an understanding of the shapes and features of the ocean, it is important to understand plate tectonics and the subduction and renewal of the oceanic crusts.
These concepts will be explored in this unit through the following activities and investigations:
Modeling Earth’s Dimensions
Diagram the layers of the earth and the study their physical characteristics.
Timeline of Earth
Develop a model to illustrate the timeline of Earth’s geological and evolutionary history.
Modeling Plate Spreading
Simulate tectonic plate spreading by modeling convection currents that occur in the mantle.
Earth’s Plates
Examine a map of the earth’s tectonic plates. Based on evidence that has been found at plate boundaries, make some hypotheses about the movement of those plates.
Continental Movement over Long Time Scales
Evaluate and interpret several lines of evidence for continental drift over geological time scales.
Crayon Rock Cycle
Simulate the rock cycle using crayons to build an understanding of the processes that occur to create sedimentary, metamorphic, and igneous rock.
Principle 7: The ocean is largely unexplored.
Ocean Literacy Fundamental Concept: New technologies, sensors and tools are expanding our ability to explore the ocean. Ocean scientists are relying more and more on satellites, drifters, buoys, subsea observatories and unmanned submersibles. (OLP 7d)
In order to build an understanding that the seafloor and oceanic crust are one of largest and least explored features of the ocean and the earth, it is important to understand the history and challenges that have been faced by deep sea exploration.
These concepts will be explored in this unit through the following activities and investigations:
Interpreting Contour Maps
Use two-dimensional maps to learn about the major landform and seafloor features of the earth.
Contour and Raised Relief Maps
Construct contour and raised relief maps of common underwater features.
Contour Lines and Nautical Charts
Use bathymetric sounding data from nautical charts to map seafloor features.
Simulating Sonar Mapping of The Ocean Floor
Simulate the collection and use of sonar data to make hypotheses about the ocean floor.
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