Glacier Dynamics- TOEFL Listening Practice Test with Answers
"Navigating through the TOEFL exam can be challenging, especially when it comes to the Listening section, which poses unique hurdles for non-native English speakers. Achieving a top score requires proficiency in every aspect of the test."
Key Highlights
Navigating through the TOEFL iBT® exam can be challenging, especially when it comes to the Listening section, which poses unique hurdles for non-native English speakers. Achieving a top score requires proficiency in every aspect of the test.
For those starting their TOEFL iBT® journey or looking to sharpen their skills, practice tests are indispensable. To assist you in your preparation, we've crafted a TOEFL iBT® Listening practice test on the topic 'Glacier Dynamics’, with a comprehensive answer key. Mastering this topic will not only enhance your listening abilities but will also pave the way for success in the TOEFL iBT® exam.
Listening Instructions:
- You can listen to each conversation and lecture only once.
- You have approximately 8 minutes to listen to the conversation/lecture and respond to the questions.
- Each question generally carries one point unless otherwise specified in the instructions, which will explicitly state the assigned points for specific questions.
- After listening to a lecture, respond to questions related to the topic based on explicit or implicit statements made by the speakers.
- Feel free to make notes as you listen. You can refer to your notes to aid in answering the questions.
- We recommend practicing note-taking with a pen and paper, similar to what you'll do during the TOEFL.
Now listen to the Audio.
Questions
Directions: Answer the questions.
- What is the primary focus of the lecture?
- Descriptions of glacier motion mechanisms
- Alterations in landscapes due to glaciers' movements
- Climate shifts affecting glacier motion
- Factors leading to the formation of glaciers
- The lecturer examines the sequence of basal slip and requests arranging the steps in the correct order:
- The pressure on the ice is increased.
- A liquid layer forms at the glacier's base.
- Friction between the glacier and bedrock diminishes.
- The glacier commences sliding.
- What are the elements contributing to the level of deformation experienced by a glacier? Choose 2 answers.
- Thickness of the glacier's ice
- Hardness of the glacier's ice
- Quantity of water beneath the glacier's ice
- Temperature of the glacier's ice
- What information does the lecturer provide regarding the velocity of glaciers?
- It impacts the quantity of ice generated by glaciers.
- It can reach a rate where movement becomes observable.
- It diminishes due to fissures in the ice.
- It is exceptionally elevated in colder climates.
- What is the professor explaining when he says this:
Professor: You are aware that ice is fragile—when struck with a hammer, it breaks like glass. However, ice also exhibits plasticity—it can alter its shape without fracturing. For instance, if a bar of ice is propped up at just one end, the unsupported end will bend due to its weight…- An attribute of ice associated with the movement of glaciers
- The initial observations leading to the understanding of glaciers' mobility by scientists
- The influence of variables such as temperature on ice resilience
- The prevalence of deformation as the primary form of glacial motion
Listen again to part of the Audio then answer the question.
- Professor: Ok, uh, let's delve into the topics of extension and compression briefly. These are categorized as types of glacial movement in your textbook, although some textbooks may exclude them.
What is the professor's suggestion regarding compression and extension?- He indicates that it plays a significant role in glacial movement.
- He suggests it is a slower form of glacial movement compared to basal slip.
- He expresses skepticism about its classification as a type of glacial movement.
- He disagrees with the idea that it leads to fissures in glaciers.
Transcript of the Audio of ‘Glacier Dynamics’
Narrator: Listen to part of a lecture in a geology class.
Professor: In our previous discussion, we delved into glaciers and their formation from crystallized snow, prompting astonishment at the immense size of certain glaciers. Despite the challenge in comprehending the movement, or flow, of such massive ice masses—a phenomenon attributed to gravity—it is widely acknowledged that glaciers' movement requires elucidation. The initial form of glacier movement, termed basal slip, stands as the primary focus of this exploration.
Basal slip, also known as sliding, essentially denotes the glacier's movement across the bedrock, specifically across a thin water layer atop the bedrock.
Uh, the process I just described should not be too difficult to visualize. Essentially, what occurs is that the lowermost layer of ice in a glacier experiences significant pressure due to the weight of the ice above it. As you may already know, when subjected to pressure, the melting point of ice is lowered. Consequently, the ice at the glacier's base melts despite being below freezing point, creating a thin film of water between the glacier and the underlying surface. This water layer acts as a lubricant, reducing friction and facilitating the glacier's movement across the bedrock. OK?
Now, the next type of movement we’ll talk about is called deformation.
You are aware that ice is fragile—when struck with a hammer, it breaks like glass. However, ice also exhibits plasticity—it can alter its shape without fracturing. For instance, if a bar of ice is propped up at just one end, the unsupported end will bend due to its weight, flattening and distorting.
Consider deformation as a gradual, slow movement akin to oozing. Depending on the pressures exerted on a glacier, its internal ice crystals undergo a reorganization process, aligning in a manner that facilitates sliding past one another. Consequently, uh the glacier moves downhill without undergoing any melting. Various factors influence the extent of deformation and the speed of glacier movement. For instance, thicker ice experiences more deformation due to the gravitational force of its weight. Temperature also contributes to this phenomenon; colder ice moves less easily compared to ice nearing its melting point, resembling the thicker consistency of oil at lower temperatures. So, glaciers in warmer regions exhibit faster flow rates than those in cooler areas.
Ok, uh, let's delve into the topics of extension and compression briefly. These are categorized as types of glacial movement in your textbook, although some textbooks may exclude them. If it weren't for your textbook including them, I might not cover them now. Essentially, the upper regions of glaciers experience lower pressure, making them less prone to deformation and more brittle. Crevasses may develop in these upper layers when the glacier encounters bedrock walls or experiences stress without deforming rapidly. This can lead to the ice expanding or contracting, causing significant fissures and cracks in the surface layers. The movement of this brittle surface ice is occasionally classified as a form of glacial movement, depending on the reference material consulted.
You may be aware that glaciers typically move at a slow pace, yet there are instances when they undergo surges, reaching speeds of up to 7,000 meters per year in certain locations. Such velocities are significantly uncommon, exceeding the usual glacier movement by hundreds of times. Witnessing glaciers in motion during these surges is a rare occurrence.
Is this your first time taking the TOEFL exam? Don’t worry! We’ve covered everything you need to know about the TOEFL iBT Exam pattern and Syllabus.
Answers and Explanations of ‘Glacier Dynamics’
1. Answer: A
Explanation: The primary focus of the lecture is Option A “Descriptions of glacier motion mechanisms”. This is evident from the professor's detailed explanation of basal slip and deformation, which are specific mechanisms describing how glaciers move. The lecture delves into the physical processes involved in glacier movement, such as the melting of ice due to pressure (basal slip) and the reorganization of ice crystals leading to sliding past each other (deformation). These descriptions emphasize the mechanisms that underlie glaciers' movements, making option A the most appropriate choice.
2. Answer: D, B, A, C
Explanation: The table is completed correctly below.
D - The glacier commences sliding: This step comes first because it describes the actual movement of the glacier across the bedrock, which is the result of the processes that follow. |
B - A liquid layer forms at the glacier's base: This step follows the initiation of sliding because as the glacier begins to move, the pressure on its base increases, leading to the melting of ice despite being below freezing point, creating a thin film of water. |
A - The pressure on the ice is increased: This step precedes the reduction of friction because it explains why the ice at the base of the glacier melts despite being below zero degrees Celsius—due to the significant pressure exerted by the weight of the overlying ice. |
C - Friction between the glacier and bedrock diminishes: This step occurs last because the formation of the liquid layer reduces friction, acting as a lubricant and facilitating the glacier's movement across the bedrock. |
Option D - The glacier commences sliding: This step comes first because it describes the actual movement of the glacier across the bedrock, which is the result of the processes that follow.
Option B - A liquid layer forms at the glacier's base: This step follows the initiation of sliding because as the glacier begins to move, the pressure on its base increases, leading to the melting of ice despite being below freezing point, creating a thin film of water.
Option A - The pressure on the ice is increased: This step precedes the reduction of friction because it explains why the ice at the base of the glacier melts despite being below zero degrees Celsius—due to the significant pressure exerted by the weight of the overlying ice.
Option C - Friction between the glacier and bedrock diminishes: This step occurs last because the formation of the liquid layer reduces friction, acting as a lubricant and facilitating the glacier's movement across the bedrock.
3. Answer: A, D
Explanation: The elements contributing to the level of deformation experienced by a glacier are Thickness of the glacier's ice and Temperature of the glacier's ice.
Option A, “Thickness of the glacier's ice”: Thicker ice experiences more deformation due to the gravitational force of its weight. This means that glaciers with greater thickness are more prone to deformation.
Option D, “Temperature of the glacier's ice”: The temperature also plays a crucial role. Colder ice does not move as easily as ice that is closer to its melting point. Warmer ice is more likely to deform and flow faster, similar to how oil is thicker at low temperatures. Thus, temperature affects the ease with which glaciers deform and move.
4. Answer: B
Explanation: The information provided by the lecturer regarding the velocity of glaciers is Option “It can reach a rate where movement becomes observable”. This is supported by the lecturer's statement that glaciers typically move at a slow pace but can undergo surges, during which they can reach speeds of up to 7,000 meters per year in certain locations. The lecturer also mentions that witnessing glaciers in motion during these surges is a rare occurrence, indicating that the velocity can become significant enough to observe the movement of glaciers.
5. Answer: A
Explanation: The correct answer is Option A, “An attribute of ice associated with the movement of glaciers”. The professor is explaining a fundamental attribute of ice that is directly related to the movement of glaciers. The fact that ice is fragile yet exhibits plasticity is crucial in understanding how glaciers deform and flow. The fragility of ice, likened to glass in its brittleness, highlights the potential for ice to break under certain conditions. This fragility is relevant to the forces acting on glaciers, such as the pressure exerted by the overlying ice causing basal slip. On the other hand, the plasticity of ice refers to its ability to change shape without fracturing. This characteristic is essential in understanding how glaciers deform and flow over time. The example provided by the professor, where a bar of ice bends under its weight when propped up at one end, illustrates this plasticity and its role in glacier movement. Therefore, the professor's explanation directly relates to an attribute of ice that is associated with the movement of glaciers, making option A the correct answer.
6. Answer: C
Explanation: The correct answer is Option C, “He expresses skepticism about its classification as a type of glacial movement”. The professor mentions that compression and extension are categorized as types of glacial movement in the textbook, but some textbooks may exclude them. This statement implies that the professor is not entirely convinced or is skeptical about the classification of compression and extension as distinct types of glacial movement. The use of words like "delve into" and "briefly" suggests that the professor is approaching this topic with a critical perspective, perhaps questioning the validity or significance of categorizing compression and extension separately from other types of glacier motion. Therefore, option C is the correct answer as it reflects the professor's skepticism or uncertainty regarding the classification of compression and extension as types of glacial movement.
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