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12. WATER (OCEANS)

Water is a vital aspect of all life forms on Earth, primarily found in oceans which make up about 71% of the planet's surface. The hydrological cycle demonstrates the continuous movement of water between different states and locations. Various factors influence oceanic features such as temperature and salinity, shaping marine ecosystems.

Sections

WATER (OCEANS)

This section examines the hydrological cycle, ocean relief, temperature distribution, and salinity, highlighting their significance in Earth's systems.

12 Section Overview

Start current section content and materials

12.1 HYDROLOGICAL CYCLE

The hydrological cycle describes the continuous movement of water on, in, and above the Earth, crucial for sustaining life.

12.2 RELIEF OF THE OCEAN FLOOR

This section discusses the characteristics and divisions of the ocean floor, highlighting major features such as the continental shelf, slope, deep sea plain, and oceanic deeps.

12.2.1 Divisions of the Ocean Floors

This section introduces the major divisions of the ocean floor, including the continental shelf, slope, deep sea plains, and oceanic deeps, along with their characteristics.

12.2.1.1 Continental Shelf

The continental shelf refers to the extended margins of continents that are submerged underwater, characterized by relatively shallow seas and diverse geological features.

12.2.1.2 Continental Slope

The Continental Slope connects the continental shelf to the deep ocean floor, characterized by steep gradients and complex geological formations.

12.2.1.3 Deep Sea Plain

The Deep Sea Plain is the flattest and most expansive regions of the ocean floor, characterized by its gently sloping areas and the impact of sediment deposition.

12.2.1.4 Oceanic Deeps or Trenches

Oceanic deeps, or trenches, are the deepest parts of the oceans, playing crucial roles in tectonic activity and marine ecosystems.

12.2.2 Minor Relief Features

Minor relief features of the ocean floor include various formations like mid-oceanic ridges, seamounts, submarine canyons, guyots, and atolls.

12.2.2.1 Mid-Oceanic Ridges

Mid-oceanic ridges are underwater mountain ranges that play a critical role in oceanic geology and the understanding of tectonic processes.

12.2.2.2 Seamount

Seamounts are underwater mountains originating from volcanic activity, rising from the ocean floor but not reaching the surface.

12.2.2.3 Submarine Canyons

Submarine canyons are deep valleys on the ocean floor that play a critical role in marine ecology and sediment transport.

12.2.2.4 Guyots

Guyots are flat-topped seamounts that have subsided over time and are found primarily in the Pacific Ocean.

12.2.2.5 Atoll

Atolls are low islands formed from coral reefs that encircle a central lagoon.

12.3 TEMPERATURE OF OCEAN WATERS

This section discusses the variations in temperature of ocean waters, including the factors that affect these variations and the significance of thermoclines.

12.3.1 Factors Affecting Temperature Distribution

This section explores the various factors influencing the temperature distribution of ocean waters, including latitude, land-water distribution, prevailing winds, and ocean currents.

12.3.2 Horizontal and Vertical Distribution of Temperature

This section explores the distribution of temperature in ocean waters, emphasizing horizontal and vertical variations and the key factors influencing these distributions.

12.4 SALINITY OF OCEAN WATERS

The salinity of ocean waters is defined by the concentration of dissolved salts in seawater and is influenced by evaporation, precipitation, and freshwater influx.

12.4.1 HORIZONTAL DISTRIBUTION OF SALINITY

This section discusses the horizontal distribution of salinity in ocean waters, explaining the factors that influence salinity levels in different regions.

12.4.2 Vertical Distribution of Salinity

Salinity in the ocean varies with depth, influenced by factors like evaporation and river input, leading to a clear stratification of saltwater layers.

1.5 EXERCISES

This section contains exercises to reinforce understanding of water-related concepts, including the hydrological cycle, ocean features, and salinity.

Learning Objectives

  • Water is essential for life and is unevenly distributed across the planet.

  • The hydrological cycle involves various processes that continually redistribute water.

  • Ocean floors exhibit diverse topography including ridges, trenches, and canyons, influenced by geological processes.

Key Concepts

Hydrological Cycle

A continuous cycle describing the movement of water in different states, including evaporation, condensation, and precipitation.

Continental Shelf

The extended margin of a continent, characterized by shallow seas, typically ending at the shelf break.

Thermocline

A transitional layer in the ocean where temperature decreases rapidly with increasing depth.

Salinity

The total content of dissolved salts in seawater, expressed in parts per thousand (ppt).

Practice Exercises

Total Questions

2

Estimated Time

4 min

Passing Score

70%

Instructions

  • Read each question carefully
  • You can use hints if you need help
  • Complete all questions before submitting