By what name is a depth map of the ocean floor known?
Correct answer: B
A bathymetric map shows the depth and features of the ocean floor. Exam tip: connect it with submarine relief maps.
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
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Easy · Level 5
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- Climatic map
- Bathymetric map
- Soil map
- Political map
Easy · Level 5
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- Sound wave
- Light ray
- Soil sample
- Air temperature
Easy · Level 5
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- Isobar
- Isotherm
- Isobath
- Isohyet
Easy · Level 5
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- Very deep narrow trench
- Shallow sea area near the coast
- High mountain chain in mid-ocean
- Volcano above water surface
Easy · Level 5
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- Continental shelf
- River valley
- Desert dune
- Glacial plain
Easy · Level 5
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- Continental slope
- Abyssal plain
- Oceanic ridge
- Coastal sand bar
Easy · Level 5
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- Coral island
- Continental shelf
- Oceanic trench
- Coastal plain
Easy · Level 5
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- Mid-oceanic ridge
- River delta
- Forest zone
- Lake basin
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- Guyot
- Seamount
- Ocean trench
- Continental slope
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- Trench
- Ridge
- Guyot
- Continental shelf
Easy · Level 5
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- Submerged deep valley
- Desert dune
- Himalayan peak
- Plain field
Easy · Level 5
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- Measuring tree height
- Recording water depth and bottom information
- Identifying cloud colour
- Measuring soil acidity
Easy · Level 5
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- Because it shows marine depth and obstacles
- Because it stops rainfall
- Because it dries the sea
- Because it shows air colour
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- It only shows coast colour
- It can measure a wide sea-floor area at once
- It stops wind direction
- It makes salt water fresh
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- It gives clues from small sea-surface variations
- It empties the ocean
- It names fishes
- It turns sand into gold
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- Between coast and river source
- Between slope and abyssal plain
- Between ridge and cloud
- Between desert and glacier
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- Deposition of sediments
- Strong wind
- Tree growth
- Rise of the Himalayas
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- Gentle slope
- Steep slope
- Equal temperature
- Equal rainfall
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- Steep slope
- Gentle slope
- Nearly level sea floor
- Irregular slope
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- River delta
- Mid-oceanic ridge
- Coastal lagoon
- Coral coast
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- Divergent boundary
- Convergent boundary
- Passive boundary
- No boundary
Easy · Level 5
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- By giving information about marine structure and depth
- By telling cloud numbers
- By increasing crop yield
- By warming air
Easy · Level 5
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- Because route depth and slope must be known
- Because tree age must be known
- Because rainfall must be stopped
- Because mountains must be painted
Easy · Level 5
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- Ocean floor features and trenches
- Class timing
- Vegetation height
- Desert sand
Easy · Level 5
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- Identification of undersea mountains and trenches
- Changing length of day
- Changing shape of moon
- Making rivers flow backward
What does sonar use to measure ocean depth?
Correct answer: A
Sonar sends sound waves and uses their echo to find depth. Exam tip: remember sonar with sound.
What is the line joining places of equal ocean depth on a map called?
Correct answer: C
An isobath joins points of equal depth in a sea or ocean, so option C is correct. An isobar joins places of equal atmospheric pressure, whereas an isotherm represents equal temperature. Exam tip: associate “bath” in isobath with water depth.
Which is the best identification of a continental shelf?
Correct answer: B
A continental shelf is a shallow area near the coast. Exam tip: connect it with resource-rich zones.
After which part does the continental slope begin?
Correct answer: A
The continental slope begins after the shelf and deepens quickly. Exam tip: remember the order of shelf and slope.
What is a very flat deep plain of the ocean floor called?
Correct answer: B
Abyssal plains are wide flat parts of the deep ocean. Exam tip: treat them as deep ocean plains.
Which feature is among the deepest features of the ocean floor?
Correct answer: C
Oceanic trenches are long narrow and very deep parts. Exam tip: connect trenches with the deepest areas.
What is a long mountain-chain-like feature on the ocean floor called?
Correct answer: A
A mid-oceanic ridge is a long raised chain on the ocean floor. Exam tip: understand it as an underwater mountain chain.
What is a mountain rising from the sea floor but not reaching the water surface called?
Correct answer: B
A seamount rises from the sea floor but often remains below the surface. Exam tip: remember it as a submerged mountain.
What is a flat-topped seamount called?
Correct answer: C
A guyot is a seamount whose summit has been eroded flat, usually by wave action when it was near sea level. Therefore, guyot is the correct answer. A ridge is a long elevated feature on the ocean floor, while a continental shelf is the shallow submerged edge of a continent. Exam tip: a flat-topped seamount is called a guyot.
A submarine canyon is similar to what?
Correct answer: A
The direct answer is A, a submerged deep valley. A submarine canyon is a long, narrow, steep-sided depression cut into the sea floor. It resembles a valley on land, but it is underwater. Such canyons may continue from the edge of a continent down the continental slope and can carry sediment into deeper parts of the ocean. Option A is correct because “submerged deep valley” describes its shape and position exactly. Option B, a desert dune, is a wind-built mound of sand on land and has the opposite form. Option C, a Himalayan peak, is a high mountain summit, not a deep channel in the ocean floor. Option D, a plain field, is broad and nearly level, whereas a canyon is narrow and deeply incised. The key is to separate “submarine” meaning under the sea from “canyon” meaning a deep valley. Memory cue: submarine canyon = underwater valley.
What is the use of hydrographic survey in ocean floor mapping?
Correct answer: B
Hydrographic survey deals with depths and bottoms of water bodies. Exam tip: connect it with navigation charts.
Why is ocean floor mapping necessary for safe navigation?
Correct answer: A
Knowing depths and obstacles helps ships choose safe routes. Exam tip: link mapping with ship safety.
What is the general advantage of multibeam sonar?
Correct answer: B
Multibeam sonar maps a wide floor area using many sound beams. Exam tip: connect it with detailed surveys.
How does satellite altimetry help in studying the ocean floor?
Correct answer: A
Small sea-surface variations can indicate large features below. Exam tip: treat satellites as a supporting technique.
Between which parts is the continental rise found?
Correct answer: B
The continental rise forms below the slope from sediments and meets the deep plain. Exam tip: treat it as a transition zone.
What is one major reason for the flatness of abyssal plains?
Correct answer: A
Sediments deposited in the deep sea cover uneven parts. Exam tip: link sediments with flatness.
What do closely spaced isobaths indicate on an ocean floor map?
Correct answer: B
Closely spaced lines show a rapid change in depth. Exam tip: remember it like the rule of contour lines.
Widely spaced isobaths show which type of slope?
Correct answer: B
Isobaths join points of equal depth. When they are widely spaced, depth changes only slightly over a horizontal distance, indicating a gentle slope of the sea floor. A steep slope produces a rapid change in depth, so its isobaths are close together. Exam tip: closer contour or isobath lines indicate a steeper slope.
Sea-floor spreading is most related to which oceanic feature?
Correct answer: B
New ocean floor formation is linked with mid-oceanic ridges. Exam tip: remember ridge and spreading together.
Oceanic trenches are generally associated with which type of plate boundary?
Correct answer: B
Trenches often form where one plate sinks beneath another. Exam tip: connect trenches with convergence.
How does ocean floor mapping help in oil and gas exploration?
Correct answer: A
Knowing marine structure helps identify possible resource areas. Exam tip: connect resource exploration with mapping.
Why is an ocean floor map needed before laying submarine cables?
Correct answer: A
The bottom structure and risks must be known for a safe cable route. Exam tip: connect it with modern communication.
Which information helps in understanding tsunami risk caused by undersea earthquakes?
Correct answer: A
Trenches and marine structures help understand seismic zones. Exam tip: remember the link between undersea earthquakes and tsunamis.
Which of the following is a direct result of ocean floor mapping?
Correct answer: A
Mapping identifies the real features of the ocean floor. Exam tip: treat identification and measurement as key results.
QUIZ COMPLETE