Ch 1 Oceans And Life Notes Class 9

“Ch 1 Oceans And Life Notes Class 9 “ is strictly based on:
Understanding Society: India And Beyond
Social Science Textbook
Grade 9| Part 2

Ocean Relief

Ocean Floor Landforms 

● Mountains ● Valleys ● Plains ● Trenches ● Ridges

Collectively called submarine relief or Oceanic relief 

⁘⁘ Mariana Trench
●●●● Pacific Ocean
●●●● Deepest place on Earth

⁘⁘ Mid-Ocean Ridge 
●●●● Hidden beneath the ocean
●●●● World’s longest mountain range 
●●●●●▸Mauna Kea 
●●●●●●◗ Hawai’i 
●●●●●●◗ Underwater mountain 
●●●●●●◗ Taller than Mount Everest

Important submarine relief features 

⁘ Continental Shelf [Imp. zone for resources ]
●●●● Submerged, shallow edge of a continent 
●●●● Extends under the ocean 
●●●●●▸ Rich in marine life
●●●●●▸ Rich in resources
●●●●●●●●◗ Oil
●●●●●●●●◗ Gas

⁘ Continental Slope
●●●● Beyond Continental shelf 
●●●● Steep slope 
●●●● Marks the true edge of a continent

Continent ➜ shelf (shallow) ➜ slope (steep) ➜ deep ocean 

⁘ Abyssal Plain
●●●● Deep ocean floor
●●●● Vast, flat, deep
●●●●●▸ Main flat expanse of the ocean floor

⁘Mid-Ocean Ridge
●●●● Immense mountain range 
●●●● Formed by volcanic activity
●●●●● ▸ Volcanic-origin ridge 

⁘ Ocean Trenches
●●●● Location: Ocean floor
●●●● Deepest parts of the ocean 

Abyssal Plain [Flat ]
Mid-Ocean Ridge [ Raised ]
Ocean Trenches [Sunken ]

Volcanic activity ➜ seamount ➜ wave action ➜ summit flattened
➜ later submerged ➜ Guyot 

Movement of Ocean Water: Waves, Tides, and Currents

◉ Ocean water is constantly in motion

⁘⁘⁘⁘ ⁘ Three movements
●●●●●●●●● Waves
●●●●●●●●● Tides
●●●●●●●●● Currents
⁘⁘⁘⁘ ⁘ Roles
●●●●●●●●● Shape Earth’s surface
●●●●●●●●● Support marine life
●●●●●●●●● Aid fishing and travel
●●●●●●●●● Influence climate

Waves

●⁘ Wave = surface of ocean rises and falls alternately 

●⁘ Cause: Winds blowing across water
●●●▸Function:
●●●●●◗ Carry energy across oceans
●●●●●◗ Over long distances

●⁘ Parts
●●●▸Crest = high peak 
●●●▸Trough = lower valley

●⁘ Coastal Architects
●●●●● Waves shape shoreline by:
●●●●●●▸Erosion
●●●●●●▸Sediment transport
●●●●●●●◗ Erosional Features
●●●●●●●●●● Sea cracks ● Caves  ● Arches  ● Sea stacks ● Stumps 

Headland ➜ sea cracks ➜ caves ➜ arches ➜ sea stacks ➜ stumps

Storm Waves

◉ Storm → strong winds → huge waves
●●●●● causes coastal damage

Tsunami

● Giant waves
● Mainly caused by underwater earthquakes
●⁘ Feature
●●▸Extremely destructive
●●▸Run-up height
●●●◗ Maximum vertical height above sea level on reaching shore
●●●◗ Up to 30 metres or more
● Most destructive wave type

Tides

● Tides = rhythmic rise and fall of ocean water
● Occur twice a day

Spring Tides

● Sun–Earth–Moon in a straight line
● On full moon and new moon days
●⁘ Feature:
●●▸Combined gravitational pull of Sun and Moon
●●▸Sometimes very high tides
●●▸Sometimes very Low tides
●●▸Water bulges on opposite sides of Earth

Sun–Earth–Moon aligned ➜ combined gravitational pull ➜ spring tides

Neap Tides

● Moon in first-quarter and third-quarter phases
●⁘ Feature:
●●●▸ Sun and Moon pull in different directions
●●●▸ Smaller difference between high and low tide
●●●▸ Weakest tidal range

Quarter Moon ➜ pulls in different directions ➜ smaller high–low difference
➜ neap tides

Importance of Tides

● Navigation

●⁍ High tide
●●●▸Raises water near shore
●●●▸Ships enter harbours easily
●⁍ Tidal range in some ports = 4–5 metres
●⁍ Before berthing, ship checks:
●●●▸Water depth
●●●▸Tidal range

● Gulf of Khambhat

●⁍ Coastal area
●⁍ Tidal range about 12 metres (Extreme)

● Singapore Strait

●⁍ Sea channel
●⁍ Shallow areas
●⁍ VLCCs (Very Large Crude Carriers) wait for hours
●⁍ Transit only at high tide

Shallow channel ➜ insufficient depth ➜ VLCC waits ➜ high tide ➜ safe transit.

Tidal Currents

= Strong currents generated by tidal change ➜ large water volumes flow in and out of coasts 

●●● 5 to 6 knots or about 9 to11 km/h 

Fishing

● High tide → fish move closer to shore 
● Better catch for fishing communities 

Energy

● Rise and fall of tidal water → electricity 

Major tidal energy site in India

●● Gulf of Kutch
●● Gulf of Khambhat
●●●⁍ 12 m tidal range 
●● Sundarbans
●●●⁍ Potential for tidal power 

Coriolis Force

● Force caused by Earth’s rotation 
● Deflects any free-moving object from its straight path 
●●⁍ Direction of deflection
●●●●▸Northern Hemisphere → right
●●●●▸Southern Hemisphere → left
● Coriolis force bends the path of ocean currents.

Ocean Currents

● Ocean currents = continuous streams of water
●⁍ Flow across the ocean surface
●●▸In definite directions
● Causes of Ocean currents
●⁍ Winds 
●⁍ Earth’s rotation (Coriolis force)
●⁍ Differences in temperature
●⁍ Differences in salinity
●⁍ Shape of continents
●⁍ Shape of ocean basins

Types of Ocean Currents

“Based on direction from which water flows”

1. Warm Current
   ● Flows from warmer regions
   ● Shown in red on maps
2. Cold Current 
   ● Flows from colder regions
   ● Shown in blue on maps

Origin of water decides whether a current is warm or cold

Examples – Ocean Currents

● Gulf Stream

●⁍ Warm current
●⁍ Originates in Gulf of Mexico, Atlantic Ocean
●●▸Feature:
●●●◗ Keeps Norwegian waters relatively warm
●●●◗ This prevents sea ice formation
●●●●●⁃ Shows how a warm current offsets high-latitude cold

Gulf of Mexico ➜ Gulf Stream (warm) ➜ Norway ➜ waters stay warm
➜ little sea ice at 60°–70° 

● Labrador Current

●⁍ Cold current
●⁍ Flows along east coast of Canada
●●▸Feature:
●●●◗ Carries freezing water
●●●◗ Supports sea ice formation 
●●●◗ Supports icebergs
●●●◗ Even at lower latitudes = High temperature

Labrador Current (cold) ➜ freezing water along Canada’s east coast → sea ice and icebergs

Cyclones and Tsunamis-Early Warning Systems 

Cyclones and Tsunamis are sudden natural hazards in oceans and seas

Early Warning Systems

● Giant alarm systems for coastal areas
●●⁍ Functions 
●●●●▸Detect cyclones and tsunamis
●●●●▸Predict disasters
●●●●▸Issue timely warnings
●●⁍ Purpose
●●●●▸People evacuate
●●●●▸People stay safe

Detection ➜ prediction ➜ timely warning ➜ evacuation ➜ lives saved

India’s Warning Services

● Services
●●⁍ Cyclone Warning Services
●●⁍ Marine Weather Services

● Coverage
●●⁍ Eastern coast
●●⁍ Western coast

● Advanced technologies predict cyclones at an early stage

Government Initiatives 

● National Cyclone Risk Mitigation Project (NCRMP)

●●⁍ Launched by Government of India
●●⁍ Focus: cyclone-prone States and Union Territories
●●●▸Feature:
●●●●●▸Builds cyclone shelters
●●●●●▸Strengthens warning systems
●●●●●▸Improves emergency response
●●●●●▸Includes Decision Support System (DSS)
●●●●●●●●⁃ For disaster management authorities

● Storm Surge Early Warning System (SSEWS)

●●⁍ Location: Indian coasts 
●●⁍ Set up by INCOIS with IMD
●●●●▸Feature:
●●●●●●⁃ Forecasts cyclone-induced storm surges
●●●●●●⁃ Forecasts extent of coastal inundation

INCOIS – Indian National Centre for Ocean Information Services

Focus on Cyclones

❖ Atmospheric disturbances over warm ocean waters cause cyclones

Atmospheric disturbance + warm ocean waters ➜ cyclone

Naming the Cyclone

● North Indian Ocean
●●⁍ Named sequentially from a list
●●⁍ 169 names
●●⁍ Submitted by 13 member countries
●●●▸This ensures:
●●●●●⁃ Clear communication
●●●●●⁃ Public awareness

Recent Examples:

Shared names keep warnings clear and quick to recognise. 

Alert Dissemination[sending Information clearly + quickly]

● Indian Tsunami Early Warning Centre (ITEWC)
●●⁍ Sends alerts to Government of India
●●●●▸Government informs:
●●●●●●⁃ State governments
●●●●●●⁃ Emergency response teams
●●⁍ Communication Channels
●●●●●●⁃ Satellite-based networks
●●●●●●⁃ SMS
●●●●●●⁃ Emails
●●●●●●⁃ Coastal display boards

ITEWC alert ➜ Government of India ➜ state governments + emergency teams ➜ public via satellite, SMS, email, display boards 

Public Awareness and Training

● Educate
●▸Officials 
●▸Coastal communities
●●●⁃ Topic: how to interpret warnings

Training ➜ warnings understood ➜ people respond appropriately when cyclone predicted

Marine Resources and Their Significance

Marine Resources

● Oceans = vast storehouses of resources
● Marine resources = materials and features in oceans
●●●⁍ Have intrinsic or economic value

● Classification:

●●●⁍ Marine Living Resources
●●●⁍ Marine Non-living Resources

●●●●●▸Examples:

●●●●●●●●1. Sand and gravel    2. Fish and seafood
●●●●●●●●3. Biodiversity            4. Oil and natural gas
●●●●●●●● 5. Minerals                  6. Sand and gravel

●●●●●●●●●●●●●7. Renewable blue energy:

●●●●●●●●●●●●●●●●●●●●▸Tidal energy
●●●●●●●●●●●●●●●●●●●●▸Wave energy

●●●●●●●●●●●●●8. Tourism potential       9. Unique ecosystems {Coral reefs}

Significance of Marine Resources

● Vital for
●●●●⁍ Food security
●●●●⁍ Economic activities
●●●●⁍ Healthy environment
● Oceans support biodiversity
●●●●⁍ Sustain plant and animal species

For India:

Long coastline ➜ fishing, trade, tourism ➜ livelihoods for millions

Therefore:

● Use marine resources  responsibly
● Do not disturb marine ecosystems

Maritime Zones

❖ Maritime zones = different areas of ocean
●●⁍ Defined by international law
●●●▸Territorial waters ➜ Contiguous zone ➜ EEZ ➜ High seas

❖ Territorial waters
●●● Sea area closest to a country
●●●⁍Feature
●●●●▸Near-complete control of the country
●●●●▸Foreign ships may pass peacefully if they obey the rules

●●● Government can make laws on:
●●●●⁍ Customs
●●●●⁍ Immigration
●●●●⁍ Pollution control

❖ Contiguous Zone
●●● Beyond territorial waters
●●● From baseline up to 24 nautical miles
●●● Limited control over:
●●●●⁍ Customs
●●●●⁍ Fiscal matters
●●●●⁍ Illegal immigration

❖ Exclusive Economic Zone (EEZ)

●●● Beyond contiguous zone
●●● Up to 200 nautical miles from coast
●●● Defined under UNCLOS by global agreement
●●●●⁍ UNCLOS= United Nations Convention on the Law of the Sea
●●● Special rights to use ocean resources:
●●●●⁍ Fish
●●●●⁍ Oil
●●●●⁍ Gas
●●● Other countries' ships pass peacefully 
●●● Country does not fully own or control EEZ waters

❖ High Seas

●●● Beyond the EEZ
●●● Also called international waters
●●● 64 per cent of world's oceans

●●●●⁍ Feature
●●●●●●▸Belong to no single country
●●●●●●▸Part of the global commons
●●●●●●▸Equal rights for all countries:
●●●●●●●●●⁃ Navigation
●●●●●●●●●⁃ Fishing
●●●●●●●●●⁃ Flying over
●●●●●●●●●⁃ Laying underwater cables
●●●●●●●●●⁃ Building floating structures
●●●●●●●●●⁃ Exploring for minerals

Challenges of EZZ:

●●⁍ Overfishing   ⁍ Illegal fishing  ⁍ Conflicts over resources
●●⁍ Navigation and safety harder to ensure
●●⁍ No clear enforcement mechanisms

●●●●▸Law that applies: flag state
●●●●●●●●⁃ Country in which a ship is registered

International Maritime Rules and Regulations

Maritime Law/Maritime regulations 

International rules and agreements for keeping Keep activities at sea safe, fair, and peaceful

Maritime Law regulates:

●Piracy ●Terrorism  ●Natural disasters  ●Accidents  ●Trade route safety
●Disputes between countries

Important Maritime Rules and Regulations

COLREGs| Avoids accidents at sea

= Convention on the International Regulations for Preventing Collisions at Sea 
●●● Sets rules of the road at sea

●●●⁍ Feature
●●●●▸lookout 
●●●●▸Deciding which ship to pass on
●●●●▸Give-way and stand-on vessels
●●●●▸Safe speed
●●●●▸Lights, sound signals, shapes
●●●●●●⁃ Shapes mark vessel types (e.g. fishing boats)
●●●●●●●▸Prevent collisions
●●●●●●●▸International signals and radio communication

MARPOL | Reduce ship pollution

= International Convention for the Prevention of Pollution from Ships

●●⁍ Feature:
●●●●▸Ships meet safety standards
●●●●▸Ships prohibited from polluting seas

COLREGs ➜ proper lookout, signals, safe speed ➜ collisions prevented

MARPOL ➜ no polluting by ships ➜ cleaner seas

Why are Maritime Rules Important?

● Safe oceans ●fair + sustainable use of resources
● Use marine resources without conflict

◈Protects: 

●●⁍ Marine life
●●⁍ ● Ships 
●●⁍ ●  Sailors
●●⁍ ●  Coastal communities
   ●●⁍●●⁍● Common standards for all ships