What is the science of measuring ocean depth called?
Correct answer: B
Bathymetry deals with measuring depths of seas and lakes. Exam tip: understand a bathymetric map as a depth map.
Geography
Mapping of the ocean floor
महासागर तल का मानचित्रण
In this Class 11 Geography topic from “Distribution of Oceans and Continents,” students learn how the ocean floor is mapped and interpreted. They explore major features such as continental shelves, slopes, deep-sea plains, mid-ocean ridges, trenches and seamounts, and understand how soundings, sonar and bathymetric maps reveal underwater relief. The topic also helps connect ocean-floor patterns with plate boundaries, seafloor spreading and the changing distribution of continents and oceans.
TOPIC PRACTICE
Quiz this set
Up to 25 questions from this page. Select your focus, then start.
25 questions
Choose questions
Easy · Level 3
View options
- Tidometry
- Bathymetry
- Seismometry
- Aerometry
Easy · Level 3
View options
- Light wave
- Heat wave
- Sound wave
- Radio wave
Easy · Level 3
View options
- Clouds
- Air
- Sun
- Sea floor
Easy · Level 3
View options
- Bathymetric map
- Political map
- Population map
- Rainfall map
Easy · Level 3
View options
- The deepest part
- Shallow submerged part near a continent
- Only volcanic islands
- High mountain range in the ocean centre
Easy · Level 3
View options
- It is a dry plain on the coast
- It is always filled with fresh water
- It forms a steep slope from shelf to deep ocean
- It is found only in rivers
Easy · Level 3
View options
- Coastal sandy plain
- Hilly island
- Glacial valley
- Broad nearly flat plain in the deep sea
Easy · Level 3
View options
- Broad shallow shelf
- Long narrow and very deep depression
- Clouds above the sea
- Coastal sand
Easy · Level 3
View options
- To reduce salt in the sea
- To stop storms
- To find depth and shape using sound waves
- To remove marine animals
Easy · Level 3
View options
- Continental slope
- Abyssal plain
- Glacial moraine
- Seamount
Easy · Level 3
View options
- Guyot
- Delta
- Pass
- Pond
Easy · Level 3
View options
- Only country borders
- Ocean floor relief
- Only rainfall zones
- Only languages
Easy · Level 3
View options
- Contour line
- Isobar
- Isobath
- Isotherm
Easy · Level 3
View options
- Colour of the ship
- Number of fish
- Taste of seawater
- Travel time of sound
Easy · Level 3
View options
- Oceanography
- Poetry studies
- Handwriting studies
- Theatre art
Easy · Level 3
View options
- It changes weather
- It shows mid-oceanic ridges and trenches
- It makes continents fixed
- It measures ocean colour
Easy · Level 3
View options
- In the sky above the ocean
- Inside deserts
- In continental shelf and slope areas
- Only on lake surface
Easy · Level 3
View options
- A house built on the coast
- A small river bend
- A cloud group over the sea
- Broad deep area of the ocean floor
Easy · Level 3
View options
- Deep sea was difficult to observe and measure directly
- There was no water in oceans
- Ships were not needed
- Oceans existed only on maps
Easy · Level 3
View options
- It measures only air
- It can measure depths over a wider area at once
- It works only on coasts
- It does not use sound
Easy · Level 3
View options
- To dry the ocean
- To build roads in the ocean
- To estimate floor relief from small sea-surface height changes
- To name fishes
Easy · Level 3
View options
- It maps only the sky
- It turns soil into gold
- It removes all mountains
- It directly measures depth by sound at the location
Easy · Level 3
View options
- Coastal geological structure differs from place to place
- All coasts are the same
- Oceans have no depth
- Shelf exists only on maps
Easy · Level 3
View options
- It helps ships choose safer routes
- It teaches ships to fly
- It empties the ocean
- It tells the distance of the Moon
Easy · Level 3
View options
- It only increases sea temperature
- It helps identify possible mineral and energy areas
- It destroys all resources
- It only counts clouds
Which type of wave is mostly used in modern measurement of sea depth?
Correct answer: C
The correct answer is option C, sound wave. Modern sea-depth measurement commonly uses echo sounding or sonar, in which a sound pulse is transmitted toward the seabed and the returning echo is detected. If the speed of sound in the water is known or suitably estimated, depth can be calculated from depth = speed × travel time ÷ 2, because the measured time covers the downward and upward journeys. Light is strongly absorbed and scattered in seawater, heat waves are not a depth-measuring method, and ordinary radio waves do not travel effectively through deep seawater. Thus sound is the suitable wave.
In echo sounding, the sound wave sent from a ship returns after striking what?
Correct answer: D
The sound wave strikes the sea floor and returns. Exam tip: depth is found from the travel time.
A map of the ocean floor is generally known as which map?
Correct answer: A
A bathymetric map shows ocean depth and relief. Exam tip: think of it as the oceanic form of a topographic map.
Which part of the ocean floor is the continental shelf?
Correct answer: B
The continental shelf is the shallow sea area near the coast. Exam tip: connect it with fisheries and mineral resources.
What is the main feature of the continental slope?
Correct answer: C
The continental slope connects the shallow shelf with deep ocean basins. Exam tip: remember slope comes after shelf.
What is an abyssal plain?
Correct answer: D
An abyssal plain is a broad and flat area in the deep ocean. Exam tip: count it among the flattest oceanic features.
How is an oceanic trench identified?
Correct answer: B
Oceanic trenches are among the deepest parts of the sea floor. Exam tip: connect trenches with subduction zones.
Why is sonar useful in ocean floor mapping?
Correct answer: C
Sonar uses sound waves to show distance and shape of the sea floor. Exam tip: study sonar with echo sounding.
What is an isolated raised mountain on the sea floor called?
Correct answer: D
A seamount rises from the sea floor but often does not reach the surface. Exam tip: connect it with volcanic origin.
A flat-topped seamount is known by which name?
Correct answer: A
A guyot is a flat-topped seamount. Exam tip: remember the difference between guyot and seamount.
What does a map showing ocean floor height and depth with colours show?
Correct answer: B
Colours and shading help understand ocean depth and shape. Exam tip: remember the role of blue shades in showing depth.
What is a line showing equal depth on the ocean floor called?
Correct answer: C
Isobaths join points of equal ocean depth. Exam tip: contours are for land and isobaths are for sea depth.
Which information is needed to calculate depth in echo sounding?
Correct answer: D
The time taken by the sound wave to return helps find depth. Exam tip: remember the relation of time and sound speed.
Ocean floor mapping is most helpful in the study of which field?
Correct answer: A
Oceanography studies ocean depth and floor features. Exam tip: connect ocean mapping with geography and oceanography.
How does ocean floor mapping help in understanding plate tectonics?
Correct answer: B
Ridges and trenches are linked with plate boundaries. Exam tip: connect ocean features with plate movements.
Where is a submarine canyon generally found?
Correct answer: C
A submarine canyon is a deep cut valley on the sea floor. Exam tip: remember it as a valley-like ocean feature.
What is an oceanic basin?
Correct answer: D
An oceanic basin is a large deep part of the ocean floor. Exam tip: connect it with abyssal plains and deep-sea features.
Why was complete knowledge of the ocean floor limited earlier?
Correct answer: A
The direct answer is option A. Earlier, complete knowledge of the ocean floor was limited because the deep sea was difficult to reach, observe and measure directly. Step by step: sunlight becomes weak with depth, pressure increases greatly, and ordinary ships cannot see the bottom. Scientists therefore needed special instruments, sound waves, underwater vehicles and later sonar mapping to estimate depth and shape. Option A correctly identifies the main difficulty. Option B is false because oceans have always contained water; the problem was studying their hidden floor, not the absence of water. Option C is false and irrelevant: ships were necessary for exploration, although ordinary ships alone were not enough for deep measurement. Option D is false because oceans are real physical water bodies, not objects existing only on maps. Modern technology gradually improved measurements and made detailed bathymetric maps possible. Exam cue: limited earlier knowledge means difficult access and measurement, not a non-existent ocean.
How does multibeam echo sounding differ from simple echo sounding?
Correct answer: B
A multibeam system uses many sound beams to show detailed relief. Exam tip: connect it with detailed mapping.
Why are satellites used in ocean floor mapping?
Correct answer: C
Satellites help estimate large floor features from sea-surface variations. Exam tip: understand satellite mapping as an indirect method.
What is one advantage of ship-based survey in ocean floor mapping?
Correct answer: D
Ship-based survey measures depth at specific locations. Exam tip: connect it with sonar survey.
Why is the width of the continental shelf not the same everywhere?
Correct answer: A
Coastal structure and geological history affect shelf width. Exam tip: remember that shelf width is uneven.
How does ocean floor mapping help navigation?
Correct answer: A
Knowledge of depth and obstacles supports safe navigation. Exam tip: remember the practical use of mapping.
How does ocean floor mapping help in finding marine resources?
Correct answer: B
Relief information makes resource areas easier to identify. Exam tip: remember the link between shelf and mineral zones.
QUIZ COMPLETE