1. Oceans and land are integral components of the Earth's system.
a) In the ocean, the pelagic and benthic zones are divided into several distinct zones. Illustrate and describe those zones. (7 marks)
b) Describe the characteristics of those zones (in question 1a) in terms of temperature, light, density, food availability, and marine life. (3 marks)
2. Coastlines occur where the land meets the sea, and they are formed by marine and land-based processes. These processes result in either erosion or deposition, creating different types of coastal landforms.
a) List three examples of coastal landforms formed by erosion and three formed by deposition. State the type of wave action that forms each landform. (3 marks)
b) What are the processes that shape the coastline? (5 marks)
c) List the main features of an ocean basin. (2 marks)
Answer (2)
The ocean is divided into pelagic and benthic zones, each with distinct characteristics like temperature, light, and marine life. Coastal landforms are shaped by erosion and deposition processes influenced by wave action. Key features include cliffs, beaches, and deltas, which showcase the dynamic interaction between the sea and land.
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Oceans and Land as Integral Components of Earth's System
a) Ocean Zones :
Epipelagic Zone : Also known as the sunlight zone, it extends from the surface to about 200 meters deep. It receives ample sunlight, supporting photosynthesis and a wide variety of marine life, including fish, plankton, and marine mammals.
Mesopelagic Zone : Known as the twilight zone, it ranges from 200 to 1,000 meters. Light decreases significantly. It's home to a variety of organisms adapted to low light, like bioluminescent species.
Bathypelagic Zone : The midnight zone extends from 1,000 to 4,000 meters. It's pitch dark with high-pressure conditions. Few species like giant squids and bioluminescent plankton survive here.
Abyssopelagic Zone : Known as the abyss, this zone stretches from 4,000 meters to the ocean floor. It is extremely cold and dark with sparse life, mainly invertebrates.
Hadal Zone : Found at ocean depths of trenches and canyons below 6,000 meters. Very few life forms, mostly specialized organisms, are found here.
Benthic Zone : This includes the ocean floor itself, where sediment and organisms dwell. It can be found at all depths and each specific depth has its own benthic community.
b) Characteristics of Ocean Zones :
Temperature : Varies greatly with depth—warmer in the epipelagic zone and freezing in the abyssopelagic zone and beyond.
Light : The amount of light decreases with depth; significant light only in the Epipelagic Zone.
Density : Increases with depth due to pressure and lower temperatures.
Food Availability : Highest in the epipelagic zone due to photosynthesis; decreases with depth. Many deeper species rely on detritus falling from above.
Marine Life : Diverse in epipelagic with fewer but highly adapted species in deeper zones.
Coastlines and Their Formation
a) Coastal Landforms :
Erosional Landforms :
Cliffs : Formed by strong wave action eroding the base.
Sea Arches : Carved through rock by wave erosion.
Caves : Created by the wave action eroding rock layers.
Depositional Landforms :
Beaches : Formed by constructive waves depositing sand.
Sandbars : Created by wave and current action depositing sediments.
Spits : Formed by longshore drift depositing sand along the coast.
b) Processes that Shape the Coastline :
Erosion : The removal of coastal material by wave action, currents, and tides.
Deposition : The laying down of sediments carried by wind, water, or ice.
Weathering : The break down of rocks through weather without movement.
Tectonic Activity : Movement of Earth's plates affects coastal formations.
Sea-level Changes : Rising or falling sea levels alter coasts.
c) Main Features of an Ocean Basin :
Mid-ocean Ridges : Underwater mountain ranges where new crust is formed.
Abyssal Plains : Flat areas on the ocean floor, covered with sediment.
