Earth Science for STEM
Quarter 2 – Module 7:
Structure and Evolution of
Ocean Basins
CO_Q2_ESS for STEM
Module 7
What I Need to Know
This module focusses on the evolution and structure of ocean basins. This aims to
provide an overview of how ocean basins are formed over a million of years ago and
what is their unique structure that geologist find most interesting. This includes
pretest, procedure/learning experience/learning activities, reflection, and posttest.
Read the directions carefully before doing all the exercises and activities.
At the end of this module, the successful learner will be able to:
1. Identify and describe the structure of the ocean basin.
2. Trace the stages of the evolution of the ocean basin.
Lesson
Structure and Evolution of
7 Ocean Basin
Over a long period of time, as plate tectonics meet and subduction occurs, a
vast geologic basin that covers the large area of Earth’s surface is formed called ocean
basins. It has different structures that describe its unique feature. Living on an
ocean planet, where 70% are covered with water, there are unseen creatures and
astounding views and features that we can discover, and one of these is the ocean
basins.
What is It
Less than 100 million years ago the supercontinent Pangea had existed.
Because of tectonic forces and processes, the supercontinent breaks apart and
ocean basins are formed. The ocean basins cover the largest area of the earth’s
surface. All of the ocean basins were formed from volcanic rock that was released
from the fissures that is located at the mid-ocean ridges, which is an underwater
mountain range formed by plate tectonics. Through subduction process and high
gravitational energy, oceanic lithosphere is forced to move under the mantle. Over
years, ocean basins are continuously evolving as four major ocean subdivision is
formed. The world ocean is divided into the North and South Pacific, North and
South Atlantic, Indian, and Arctic Oceans. They are all distinct based on their stage
of geological evolution.
Pacific Ocean basin is the largest, deepest, and oldest existing ocean basin.
More trenches, and more frequent tsunamis happen here. It has been shaped by
plate tectonics. The second largest ocean basin is the Atlantic followed by the
Indian ocean basin. The smallest of the earth’s ocean basins is Arctic and is covered
by ice.
Through the formation of ocean basins, different features and structures are
formed. See figure 2 below.
1. Continental shelf- Partly shallow extension of the continent underwater.
2. Continental slope- Transition zone of continental shelf and deep ocean floor. It
starts from oceanic crust to continental crust.
3. Continental rise- It is where the ocean begins. All basaltic and oceanic rocks
are found here. It is the place where the sediments from land are washed. The
continental margin starts from continental shelf up to continental rise.
4. Abyssal plain- The flattest part of the ocean. 50 % of the earth’s surface is being
covered by this plain.
5. Island- It’s not just a piece of land floating up in the middle of the sea, it is part
of the ocean basin that extends up from the ocean floor.
6. Seamount- It is an undersea mountain. The erosion caused by waves destroyed
the top of a seamount which caused it to be flattened.
7. Trench- It is the deepest part of the ocean.
8. Mid-oceanic ridge- The seafloor mountain system which is situated in the
middle of the ocean basin. It is where upwelling of magma happens which
causes the sea floor to spread.
Figure 1. The ocean basin
Figure 2. Cross section of ocean basin
Evolution of the Ocean Basin
The Wilson Cycle explains the process of the opening (beginning) and
the closing (end) of an ocean which is driven by Plate Tectonics. This
process is named after the Canadian Geophysicist J. Tuzo Wilson (1908-
1993).
It is divided into 6 stages namely:
1. Embryonic Ocean Basin
2.Juvenile Ocean Basin
3. Mature Ocean Basin
4. Declining Ocean Basin
5. Terminal Ocean Basin
6. Suturing (Continental collision)
The table below gives details on each stage of Wilson Cycle
Table 1. Stages of Wilson Cycle
Stage Description Example
Embryonic ● Motion: Uplift East African
Rift Valleys
● Complex
system of
linear rift
valleys on
continent
Juvenile ● Motion: Red Sea
Divergence
(Spreading)
● Narrow seas
with
matching
coasts
Mature ● Motion: Atlantic and
Divergence Arctic
(Spreading) Oceans
● Ocean basin
with
continental
margins
Declining ● Motion: Pacific
Convergent Ocean
(Subduction)
● Islands arcs
and trenches
around basin
edge
Terminal ● Motion: Mediterrane
Convergent an Seas
(Collision and
Uplift)
● Narrow,
irregular seas
with young
mountains
Suturing ● Motion: Himalayas
Convergence Mountains
and Uplift
● Young to
mature
mountain
belts
What’s More
The Ocean Basin
Label the structures of ocean basin below. Choose your answer from the
word bank provided
Continental shelf Abyssal plain Trench
Island Continental rise Mid-oceanic ridge
Seamount Continental slope
Continental Shelf
Continental Slope Mid-oceanic Ridge Island
Continental Rise Abyssal Plain
Seamount Trench
What I Have Learned
Fill in the Table
Complete the table below. Use the details inside the box. Write your answers
in a separate sheet of paper.
Uplift Terminal Pacific Ocean
Narrow seas Himalayas Mountains Spreading
Young to mature
Mature Island Arcs and trenches
mountains
Mediterranean Seas Convergence and Uplift Red Sea
Stages Motion Description Example
Complex system
East African Rift
1. Embryonic Uplift of linear rift
Valleys
valleys
2. Juvenile Divergence
Narrow seas Red Sea
Ocean basin with
Atlantic and Arctic
Spreading Continental
3. Mature Oceans
Margins
4. Declining Subduction
Island Arcs and Pacific Ocean
trenches
Narrow irregular
Collision and
5. Terminal seas with young Mediterranean Seas
Uplift
mountains
6. Suturing Convergence and Young to mature Himalayas Mountains
Uplift mountains
References
Books
Bayo-Ang, Roly B., Maria Lourdes G. Coronacion, Anna Mae T.
Jorda and Anna Jamille Restubig. 2016. Earth and Life
Science for Senior High School. Educational Resources
Corporation.
Olivar, Jose, Raymond Rodolfo and Hillel Cabria. 2016. Exploring
Life Through Science Series. Phoenix Publishing House, Inc.
Online Resources
Retrieved on May 30, 2020:
https://www.britannica.com/science/stratification- geology
Retrieved on May 30, 2020:
http://sciencenetlinks.com/lessons/how-
sedimentary-rocks-are-formed/
Retrieved on May 30, 2020:
https://www.barrons.com/articles/great- escapes-
the-majesty-of-petra-jordan-01559338200
Retrieved on May 30, 2020:
https://study.com/academy/lesson/
stratification-definition-theory-examples.html
Retrieved on May 31,2020: https://www.youtube.com/watch?
v=0_8eI0H1tR0&t=8s Retrieved on May 31,2020:
https://www.rsc.org/education/teachers/resources
Retrieved on May31, 2020: https://www.usgs.gov/natural-
hazards/earthquake- hazards/science/tracking-stress-buildup-
and-crustal-deformation?qt- science_center_objects=0#qt-
science_center_objects
Retrieved on May 31, 2020:
https://www.geolsoc.org.uk/ks3/gsl/education
Retrieved on May 31, 2020: https://pubs.usgs.gov/gip/fossils/rocks-
layers.html
Retrieved on August 11, 2021:
https://www.nationalgeographic.org/encyclopedia/ rock-cycle/
