Lesson Notes By Weeks and Term - Senior Secondary 2

TERM – 3^RD TERM

WEEK TEN

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Geography

Topic: HYDROSPHERE (OCEAN BASIN)

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

1. Identify and describe the major parts of the ocean basins
2. Explain ocean salinity and the factors that determine the salinity of the oceans
3. Discuss the meaning, causes types and effects of ocean currents on the adjacent coastlands.
4. Examine the importance of the oceans to man

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

NOTE

HYDROSPHERE (OCEAN BASIN)

An ocean basin is a large, low-lying area on Earth's surface that is filled with seawater. It encompasses the entire ocean floor and is often characterized by distinct features such as continental shelves, slopes, abyssal plains, mid-ocean ridges, and ocean trenches. Ocean basins are the vast expanses where the world's oceans are situated, covering about 71% of the Earth's surface.

The major parts of the ocean basin include:

1. Continental Shelf: Shallow, nearshore area extending from the coast.
2. Continental Slope: Steeper region beyond the continental shelf, leading to deeper waters.
3. Abyssal Plain: Vast, flat expanses of the ocean floor in deeper areas.
4. Mid-Ocean Ridges: Underwater mountain ranges formed by tectonic activity, often associated with volcanic activity.
5. Ocean Trenches: Deep, elongated depressions in the ocean floor, typically found in subduction zones.

Ocean Salinity

Ocean salinity refers to the concentration of dissolved salts in seawater, typically measured in parts per thousand (ppt). The average salinity of the world's oceans is about 35 ppt. Several factors influence ocean salinity, they include:

1. Evaporation: As seawater evaporates, freshwater is removed, leaving behind a higher concentration of salts. Regions with high evaporation rates, like the tropics, tend to have higher salinity.
2. Precipitation: Rainfall and snowmelt introduce freshwater into the ocean, reducing salinity. Areas near the equator and those experiencing high precipitation have lower salinity.
3. Ice Melting: Melting ice from polar regions contributes freshwater, decreasing salinity in those areas.
4. River Input: Rivers transport freshwater to the oceans, diluting seawater. Coastal regions near river mouths often exhibit lower salinity.
5. Ocean Currents: Currents can transport water with different salinities. For example, warm currents from low-latitude regions carry higher salinity water to higher latitudes.

 Ocean Currents

Ocean currents are continuous, directed movements of seawater. They play a crucial role in shaping the Earth's climate, redistributing heat, and influencing marine ecosystems.

Causes of Ocean Currents

Ocean currents are primarily driven by wind, temperature, salinity, and Earth's rotation. The major forces include:

1. Wind: Surface winds push water, generating surface currents.
2. Temperature and Salinity: Variations in water density due to temperature and salinity differences lead to vertical and deep currents.
3. Coriolis Effect: Earth's rotation causes the deflection of currents, resulting in the formation of gyres.

Types of Ocean Currents

1. Surface Currents: Occur in the upper layer and are mainly driven by wind. Examples include the Gulf Stream.
2. Deep Ocean Currents: Flow in deeper layers, influenced by temperature and salinity. The Thermohaline Circulation is a significant deep current.

Effects on Adjacent Coastlands

1. Temperature Regulation: Warm currents raise coastal temperatures, while cold currents have a cooling effect.
2. Climate Influence: Currents can modify local climates, affecting precipitation patterns and weather conditions.
3. Erosion and Deposition: Strong currents contribute to coastal erosion or deposition of sediments, shaping the coastline.
4. Biodiversity: Currents influence nutrient distribution, affecting marine ecosystems and fisheries along coastlines.
5. Navigation and Trade Routes: Historical trade routes and navigation were often influenced by predictable ocean currents.

Importance of Oceans to Man

The oceans are of paramount importance to humankind for various reasons:

1. Oceans play a critical role in regulating the Earth's climate. They absorb and store large amounts of heat, influencing temperature and weather patterns globally.
2. Oceans support a vast array of marine life, contributing significantly to global biodiversity. They are a crucial source of food, with fisheries providing sustenance for millions of people worldwide.
3. Oceans are rich in resources such as fish, shellfish, and algae, which form the basis of a multi-billion dollar fishing industry. Additionally, they contain valuable minerals, oil, and natural gas.
4. Oceans serve as major highways for international trade, facilitating the transportation of goods between countries. Ports and shipping routes are vital components of the global economy.
5. Oceans are popular destinations for recreation and tourism. Beaches, coastal resorts, and marine activities contribute significantly to the tourism industry.
6. Phytoplankton in the oceans produce a substantial portion of the Earth's oxygen through photosynthesis. This oxygen is crucial for the survival of terrestrial and marine life.
7. Oceans absorb and store large amounts of carbon dioxide, playing a vital role in mitigating climate change. However, this also leads to ocean acidification, impacting marine ecosystems.

EVALUATION: 1. What is River basin?

2. Identify and discuss the major parts of the ocean basins
3. Define ocean Salinity and identify 4 factors that influence ocean Salinity.
4. Mention 5 importance of the ocean to Man

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively