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Water on Mars
Section A
Photographic evidence suggests that liquid water once existed in great quantity on the surface of Mars. Two types of flow features are seen: runoff channels and outflow channels. Runoff channels are found in the southern highlands. These flow features are extensive systems—sometimes hundreds of kilometers in total length—of interconnecting, twisting channels that seem to merge into larger, wider channels. They bear a strong resemblance to river systems on Earth, and geologists think that they are dried-up beds of long-gone rivers that once carried rainfall on Mars from the mountains down into the valleys. Runoff channels on Mars speak of a time 4 billion years ago (the age of the Martian highlands), when the atmosphere was thicker, the surface warmer, and liquid water widespread.
Section B
Outflow channels are probably relics of catastrophic flooding on Mars long ago. They appear only in equatorial regions and generally do not form extensive interconnected networks. Instead, they are probably the paths taken by huge volumes of water draining from the southern highlands into the northern plains. The onrushing water arising from these flash floods likely also formed the odd teardrop-shaped “islands” (resembling the miniature versions seen in the wet sand of our beaches at low tide) that have been found on the plains close to the ends of the outflow channels. Judging from the width and depth of the channels, the flow rates must have been truly enormous—perhaps as much as a hundred times greater than the 105 tons per second carried by the great Amazon River. Flooding shaped the outflow channels approximately billion years ago, about the same time as the northern volcanic plains formed.
Section C
Some scientists speculate that Mars may have enjoyed an extended early period during which rivers, lakes, and perhaps even oceans adorned its surface. A 2003 Mars Global Surveyor image shows what mission specialists think may be a delta—a fan-shaped network of channels and sediments where a river once flowed into a larger body of water, in this case a lake filling a crater in the southern highlands. Other researchers go even further, suggesting that the data provide evidence for large open expanses of water on the early Martian surface. A computer-generated view of the Martian north polar region shows the extent of what may have been an ancient ocean covering much of the northern lowlands. The Hellas Basin, which measures some 3,000 kilometers across and has a floor that lies nearly 9 kilometers below the basin’s rim, is another candidate for an ancient Martian sea.
Section D
These ideas remain controversial. Proponents point to features such as the terraced “beaches” shown in one image, which could conceivably have been left behind as a lake or ocean evaporated and the shoreline receded. But research suggests that the terraces could also have been created by geological activity, perhaps related to the geologic forces that depressed the Northern Hemisphere far below the level of the south, in which case they have nothing whatever to do with Martian water. Furthermore, Mars Global Surveyor data released in 2003 seem to indicate that the Martian surface contains too few carbonate rock layers—layers containing compounds of carbon and oxygen—that should have been formed in abundance in an ancient ocean. Their absence supports the picture of a cold, dry Mars that never experienced the extended mild period required to form lakes and oceans. However, more recent data imply that at least some parts of the planet did in fact experience long periods in the past during which liquid water existed on the surface.
Section E
Aside from some small-scale gullies (channels) found since 2000, which are inconclusive, astronomers have no direct evidence for liquid water anywhere on the surface of Mars today, and the amount of water vapor in the Martian atmosphere is tiny. Yet even setting aside the unproven hints of ancient oceans, the extent of the outflow channels suggests that a huge total volume of water existed on Mars in the past. Where did all the water go? The answer may be that virtually all the water on Mars is now locked in the permafrost layer under the surface, with more contained in the planet’s polar caps.
Reading Passage Vocabulary
Section A
Photographic evidence suggests that liquid water once existed in great quantity on the surface of Mars. Two types of flow features are seen: runoff channels and outflow channels. Runoff channels are found in the southern highlands. These flow features are extensive systems—sometimes hundreds of kilometers in total length—of interconnecting, twisting channels that seem to merge into larger, wider channels. They bear a strong resemblance to river systems on Earth, and geologists think that they are dried-up beds of long-gone rivers that once carried rainfall on Mars from the mountains down into the valleys. Runoff channels on Mars speak of a time 4 billion years ago (the age of the Martian highlands), when the atmosphere was thicker, the surface warmer, and liquid water widespread.
Section B
Outflow channels are probably relics of catastrophic flooding on Mars long ago. They appear only in equatorial regions and generally do not form extensive interconnected networks. Instead, they are probably the paths taken by huge volumes of water draining from the southern highlands into the northern plains. The onrushing water arising from these flash floods likely also formed the odd teardrop-shaped “islands” (resembling the miniature versions seen in the wet sand of our beaches at low tide) that have been found on the plains close to the ends of the outflow channels. Judging from the width and depth of the channels, the flow rates must have been truly enormous—perhaps as much as a hundred times greater than the 105 tons per second carried by the great Amazon River. Flooding shaped the outflow channels approximately billion years ago, about the same time as the northern volcanic plains formed.
Section C
Some scientists speculate that Mars may have enjoyed an extended early period during which rivers, lakes, and perhaps even oceans adorned its surface. A 2003 Mars Global Surveyor image shows what mission specialists think may be a delta—a fan-shaped network of channels and sediments where a river once flowed into a larger body of water, in this case a lake filling a crater in the southern highlands. Other researchers go even further, suggesting that the data provide evidence for large open expanses of water on the early Martian surface. A computer-generated view of the Martian north polar region shows the extent of what may have been an ancient ocean covering much of the northern lowlands. The Hellas Basin, which measures some 3,000 kilometers across and has a floor that lies nearly 9 kilometers below the basin’s rim, is another candidate for an ancient Martian sea.
Section D
These ideas remain controversial. Proponents point to features such as the terraced “beaches” shown in one image, which could conceivably have been left behind as a lake or ocean evaporated and the shoreline receded. But research suggests that the terraces could also have been created by geological activity, perhaps related to the geologic forces that depressed the Northern Hemisphere far below the level of the south, in which case they have nothing whatever to do with Martian water. Furthermore, Mars Global Surveyor data released in 2003 seem to indicate that the Martian surface contains too few carbonate rock layers—layers containing compounds of carbon and oxygen—that should have been formed in abundance in an ancient ocean. Their absence supports the picture of a cold, dry Mars that never experienced the extended mild period required to form lakes and oceans. However, more recent data imply that at least some parts of the planet did in fact experience long periods in the past during which liquid water existed on the surface.
Section E
Aside from some small-scale gullies (channels) found since 2000, which are inconclusive, astronomers have no direct evidence for liquid water anywhere on the surface of Mars today, and the amount of water vapor in the Martian atmosphere is tiny. Yet even setting aside the unproven hints of ancient oceans, the extent of the outflow channels suggests that a huge total volume of water existed on Mars in the past. Where did all the water go? The answer may be that virtually all the water on Mars is now locked in the permafrost layer under the surface, with more contained in the planet’s polar caps.
IELTS Academic Reading Tips for Success
Tips to improve your reading speed
Keep in mind, having a slow reading speed makes skimming or scanning a reading passage more difficult. The process of quickly skimming through a reading passage for specific keywords or main ideas is a requirement for you to employ successful reading strategies to improve your IELTS reading score. In other words, skimming and scanning are critical skills to ensure you complete all questions in the allotted time frame.
IELTS Reading Strategies
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Step 1: Read questions first
One of the most common mistakes that candidates make when approaching the reading exam is reading every single word of the passages. Although you can practice for the exam by reading for pleasure, "reading blindly" (reading without any sense of what the questions will ask) will not do you any favors in the exam. Instead, it will hurt your chances for effectively managing your time and getting the best score.
The main reason to read the questions first is because the type of question may determine what you read in the passage or how you read it. For example, some question types will call for the "skimming" technique, while others may call for the "scanning" technique.It is important to answer a set of questions that are of the same question type. You'll need to determine which question type you want to tackle first. A good strategy would be to start with the easier question type and move on to more difficult question types later. The Easiest question types are the ones where you spend less time reading. For example, the Matching Heading question type is an easier one because you only need to find the heading that best describes the main idea of a paragraph. An example of a difficult question type would be Identifying Information. For this question type, you'll need to read each paragraph to find out if each statement is TRUE, FALSE, or NOT GIVEN according to the passage.
Here is a table that lists the difficulty levels for each question type. Use this table as a reference when choosing which question type you want to tackle first.
Difficulty level Question Type Easy Sentence Completion
Short answerMedium Matching Features
Multiple choice
Matching Headings
Summary, Table, Flow-Chart CompletionDifficult Matching Sentence Endings
Matching Information
Identifying Information (TRUE/FALSE/NOT GIVEN)
Identifying Viewer's claims (YES/NO/NOT GIVEN)
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Step 2: Read for an objective
After you've read the questions for the passage, you will be able to read for an objective. What does this mean? For example, if you come across a question that includes the year "1896", you can make a note of when this year comes up in the text, using it to answer the question later on. There are two reading techniques that will help you stay on track with reading for an objective. The first one, skimming, is best defined as reading fast in order to get the "gist", or general idea, or a passage. With this technique, you are not stopping for any unfamiliar words or looking for specific details. The second technique, scanning, is best defined as reading for specific information. With this technique, you are not reading for the overall gist, but rather, specific information. Notice how each of these techniques has a specific objective in mind. This will help you find information more quickly.
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Step 3: Take notes
As you're reading for an objective, you should also be making notes on the margins of the passage, placing stars next to key information, or underlining things that you believe will help you answer the various questions. This will make it easier for you to check back when you are asked certain things in the questions. Choose whichever note-taking system is right for you - just make sure you do it!
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Step 4: Answer wisely
After you've read the questions, read the passage, and have taken any appropriate notes, you you should have located the part of the text where you where you need to read carefully. Then just read carefully and think critically to determine the correct answer.
IELTS Reading Question Types
The IELTS reading test contains many different question types:
| Matching Headings | IELTS Reading Lesson: Matching Headings |
| Matching Information | IELTS Reading Lesson: Matching Information |
| Matching Features | IELTS Reading Lesson: Matching Features |
| Summary Completion | IELTS Reading Lesson: Summary Completion |
| Identifying Information | IELTS Reading Lesson: Identifying Information |
| Identifying Writer's claims | IELTS Reading Lesson: Identifying Writer's claims |
| Multiple Choice | IELTS Reading Lesson: Multiple Choice |
| Short Answer | IELTS Reading Lesson: Short Answer |
| Match Sentence Ending | IELTS Reading Lesson: Match Sentence Ending |
| Sentence Completion | IELTS Reading Lesson: Sentence Completion |
| Table Completion | IELTS Reading Lesson: Table Completion |