Read this article in 4 levels: Basic A1 (英検3級), Intermediate B1(英検2級), Advanced C1(英検1級), original version. Multiple choice content questions for each level. Free English reading practice. The more you read in English, the more your English will improve. How quickly does a river cut through rock?
A1 Beginner 英検3級
B1 Intermediate 英検2級
C1 Advanced 英検1級
Original article
Basic A1 (英検3級) Version:
Article:
How quickly does a river cut through rock? It depends on the kind of rock, the stuff the water carries, how much water there is, how fast the water flows, and how acidic the water is.
This is not an easy question. We often think about the Grand Canyon when we talk about rivers cutting through rock. The Grand Canyon is very deep, about 1,200 meters, and in some places, it is 2,000 meters deep. The Colorado River made the Grand Canyon, and it took about five or six million years to make it this deep. But the Colorado River could cut through the rock because of special conditions.
The type of rock is the most important thing. The rocks in the Grand Canyon are sedimentary rocks. These rocks formed under a shallow sea a long time ago. They are made of pieces of other rocks, sand, dirt, and dead animals and plants. These things sank to the bottom of the sea and got compressed. The top layers of the Grand Canyon are limestone and sandstone. These are not strong rocks. They crumble and break easily, so the Colorado River could cut through them. If the rocks had been granite, a much harder rock, the Colorado River might have formed a lake instead of a canyon. Softer rocks like sandstone are easily eroded, while harder rocks like granite are not.
The next thing to think about is what the river carries. Water alone does not cut through rock very quickly. But when a river carries sand or small rocks, these things act like sandpaper and slowly scrape off the rock in the river. The Colorado River carried a lot of sand, which helped it cut through the rocks faster.
The amount of water in the river is also important. More water means the river can carry more sand and rocks, and it has more energy to cut through the rock. The Colorado River had a flow rate of 109,557 liters per second when it was cutting through the Grand Canyon. Now it has less water because some of it is used for farming. The Amazon River has the highest flow rate in the world, with 220,000,000 liters per second. The Amazon River flows quickly because it starts in high mountains and ends at sea level. Gravity pulls the water down fast. The same thing happened with the Colorado River.
Finally, the acidity of the water matters. If the water is more acidic, it can dissolve some types of rocks, like limestone. Acidic water can make the calcium carbonate in limestone turn into carbon dioxide and water. But acidic water cannot erode harder rocks.
So, the speed at which a river cuts through rock depends on many things: the type of rock, the sand and rocks it carries, its speed, its amount of water, and how acidic it is.
Questions:
- What is the Grand Canyon?
a) A big lake
b) A deep canyon made by a river
c) A mountain
d) A kind of rock - What kind of rocks are in the Grand Canyon?
a) Granite
b) Sandstone and limestone
c) Basalt
d) Marble - What helps a river cut through rock faster?
a) Soft rocks
b) Hard rocks
c) Cold water
d) Flat land - What does the Colorado River carry that helps it erode rocks?
a) Air
b) Sand and small rocks
c) Fish
d) Trees - Why does the Amazon River flow quickly?
a) It is very wide
b) It starts in high mountains
c) It has no rocks
d) It is very short - How does acidic water affect limestone?
a) It makes it harder
b) It dissolves the rock
c) It turns into sand
d) It makes the water blue - What is the most important factor in how quickly a river cuts through rock?
a) The kind of rock
b) The color of the water
c) The temperature
d) The amount of sunlight - How long did it take for the Colorado River to form the Grand Canyon?
a) 1 million years
b) 5 or 6 million years
c) 10,000 years
d) 100,000 years - What is one thing that does not help a river erode rock?
a) A lot of water
b) Acidic water
c) Hard rocks
d) Sand and small rocks - What can we assume if a river has cut down through a plain?
a) The plain is made of hard rock
b) The plain is made of soft rock
c) The river is slow
d) The river is new
Answers:
- b) A deep canyon made by a river
- b) Sandstone and limestone
- a) Soft rocks
- b) Sand and small rocks
- b) It starts in high mountains
- b) It dissolves the rock
- a) The kind of rock
- b) 5 or 6 million years
- c) Hard rocks
- b) The plain is made of soft rock
Intermediate B1 (英検2級) Version:
Article:
How quickly can a river cut through rock? This depends on several factors: the type of rock, the sediment the water carries, the amount of water, the speed of the water, and the water’s acidity.
This isn’t an easy question to answer. When thinking about the power of water to erode rock, we often think of the Grand Canyon. It is about 1,200 meters deep on average and 2,000 meters at its deepest point. The Colorado River created the Grand Canyon, taking around five or six million years to erode the rock to its current depth. However, this erosion was possible due to specific conditions.
The type of rock is the most crucial factor. The rocks in the Grand Canyon are sedimentary rocks, which formed when the area was under a shallow sea. These rocks are made from compressed pieces of other rocks, sand, dirt, and dead animals and plants. The upper layers of the Grand Canyon are made of limestone and sandstone, which are relatively soft rocks. These rocks crumble easily, which is why the Colorado River could erode them so effectively. If the area had been made of granite, a much harder rock, the river might not have been able to form a canyon. Instead, it might have created a lake or found a different route. Softer rocks like sandstone are more easily eroded, while harder rocks like granite are more resistant.
Another important factor is the sediment the river carries. Water alone doesn’t erode rock very quickly. However, when a river carries sand or small rocks, these act like sandpaper, gradually wearing down the rock. The Colorado River carried a lot of sand from the surrounding sandstone, speeding up the erosion process.
The volume of water in the river is also a significant factor. The more water a river carries, the more sediment it can transport, and the more energy it has to erode rock. The Colorado River once had a flow rate of 109,557 liters per second, though it is much lower now due to irrigation. The Amazon River, the river with the highest flow rate in the world, moves 220 million liters per second. The Amazon flows quickly because it starts in high mountains and descends to sea level, gaining speed due to gravity. The Colorado River also had a similar situation at the beginning, with tectonic plate movements raising the river and surrounding plains, giving it the speed to erode the rock.
Finally, the acidity of the water plays a role. More acidic water can dissolve minerals in certain types of rocks, like limestone. When limestone is exposed to acidic water, the calcium carbonate in the rock turns into carbon dioxide and water. This process is becoming more common as the amount of carbon dioxide in the atmosphere increases, leading to more acidic rivers. However, acidic water cannot erode harder rocks like granite.
In conclusion, the speed at which a river cuts through rock depends on the type of rock, the sediment it carries, the speed and volume of the water, and the acidity of the water. Even with these factors, there are still many variables, making this a complex question.
Questions:
- What is the primary factor that affects how quickly a river can erode rock?
a) The type of rock
b) The temperature of the water
c) The color of the water
d) The presence of fish - What kind of rock forms the upper layers of the Grand Canyon?
a) Granite
b) Limestone and sandstone
c) Basalt
d) Marble - How does the sediment in the river help in erosion?
a) It makes the water warmer
b) It acts like sandpaper to wear down the rock
c) It slows down the water
d) It prevents erosion - What is the flow rate of the Colorado River when it was eroding the Grand Canyon?
a) 220 million liters per second
b) 109,557 liters per second
c) 100,000 liters per second
d) 50,000 liters per second - Why does the Amazon River flow so quickly?
a) It is very wide
b) It starts in high mountains and flows to sea level
c) It has no rocks
d) It is the longest river - How does acidic water affect limestone? a) It makes it stronger
b) It dissolves the rock
c) It turns it into sand
d) It makes the water blue - Why might the Colorado River not have created the Grand Canyon if the rock had been granite?
a) Granite is too soft
b) Granite is harder and more resistant to erosion
c) Granite is only found in mountains
d) Granite does not react to acidic water - What role does the volume of water in a river play in erosion?
a) It determines the color of the water
b) More water means more sediment can be carried, increasing erosion
c) It slows down the erosion process
d) It makes the water clearer - What happens when limestone is exposed to acidic water?
a) It gets stronger
b) It turns into carbon dioxide and water
c) It becomes granite
d) It forms new rocks - What makes the question of how quickly a river can erode rock complex?
a) There are many factors involved
b) The answer is simple
c) Only the Colorado River can erode rock quickly
d) Rivers do not erode rock
Answers:
- a) The type of rock
- b) Limestone and sandstone
- b) It acts like sandpaper to wear down the rock
- b) 109,557 liters per second
- b) It starts in high mountains and flows to sea level
- b) It dissolves the rock
- b) Granite is harder and more resistant to erosion
- b) More water means more sediment can be carried, increasing erosion
- b) It turns into carbon dioxide and water
- a) There are many factors involved
Advanced C1 (英検1級) Version:
Article:
How quickly does a river cut through rock? The answer depends on several factors, including the type of rock, the sediment carried by the water, the volume and speed of the water, and the acidity of the water.
This is a complex question, often exemplified by the Grand Canyon. The Grand Canyon, with an average depth of around 1,200 meters and a maximum depth of 2,000 meters, was formed by the Colorado River over approximately five to six million years. However, the river’s ability to carve out such a massive canyon was due to specific conditions that allowed for significant erosion.
The type of rock is the most significant factor influencing how quickly a river can erode the landscape. The rocks in the Grand Canyon are primarily sedimentary, formed when the area was submerged under a shallow sea. These rocks consist of compressed particles from other rocks, sand, dirt, and organic material. The upper layers of the Grand Canyon are composed of limestone and sandstone, both relatively soft and easily eroded. If the rock had been granite, a much harder material, the river likely would not have formed a canyon. Instead, the river might have created a lake or sought an alternative route. Sedimentary rocks, particularly those with smaller grains or that fracture easily, are more susceptible to erosion than harder rocks like granite or basalt.
Another key factor is the sediment carried by the river. Water alone is not highly effective at eroding rock. However, when a river carries sand or small rocks, these act like sandpaper, gradually wearing down the riverbed and banks. The Colorado River carried significant amounts of sand from the surrounding sandstone, which accelerated the erosion process.
The volume of water in the river also plays a crucial role. A larger volume of water can carry more sediment and has more energy to erode rock. The Colorado River once had a flow rate of 109,557 liters per second during the time it carved the Grand Canyon, though it is much reduced today due to irrigation diversions. The Amazon River, which has the highest flow rate of any river in the world, moves 220 million liters of water per second. The Amazon’s speed is partly due to the significant elevation difference from its source in the Andes mountains to its mouth at sea level. This elevation difference generates the gravitational pull necessary for high-speed water flow. The Colorado River had a similar situation in its early days, with tectonic activity raising the river and surrounding plains, thus providing the speed needed to erode the rock.
Lastly, the acidity of the water influences the erosion process. Water that is more acidic can dissolve certain minerals in the rock, particularly in sedimentary rocks like limestone. When exposed to acidic water, the calcium carbonate in limestone converts to carbon dioxide and water, effectively eroding the rock. The increasing acidity of rivers due to higher atmospheric carbon dioxide levels is a growing concern. However, acidic water does not have the same effect on harder rocks like granite.
In conclusion, the rate at which a river can erode rock is determined by the type of rock, the sediment load, the water’s speed and volume, and its acidity. Despite these factors, other variables also influence the process, making it a complex question with no straightforward answer.
Questions:
- What are the primary factors that determine how quickly a river can erode rock?
a) Temperature and wind speed
b) Type of rock, sediment load, water volume and speed, acidity
c) The presence of vegetation
d) The river’s length and width - Why is the type of rock crucial in determining erosion speed?
a) Harder rocks erode faster
b) Softer rocks, like sedimentary rocks, are more easily eroded
c) All rocks erode at the same rate
d) Erosion does not depend on the type of rock - How did the Colorado River form the Grand Canyon?
a) By flowing slowly over millions of years
b) By eroding sedimentary rocks under specific conditions
c) By carrying very little sediment
d) By moving through granite - What role does sediment play in river erosion?
a) It speeds up the erosion process by acting like sandpaper
b) It slows down the river’s flow
c) It has no effect on erosion
d) It only affects the color of the water - How does the volume of water in a river affect erosion?
a) Larger volumes of water carry more sediment and have more energy for erosion
b) Volume has no effect on erosion
c) Smaller volumes of water erode faster
d) Volume affects only the river’s depth - What happens when limestone is exposed to acidic water?
a) It hardens
b) It dissolves, turning into carbon dioxide and water
c) It changes color
d) It becomes more resistant to erosion - Why might the Grand Canyon not exist if the rock had been granite?
a) Granite is too soft to form a canyon
b) Granite is harder and more resistant to erosion
c) Granite is only found underwater
d) Granite cannot form sedimentary layers - How has the acidity of rivers changed due to atmospheric conditions?
a) Rivers have become more acidic due to increased carbon dioxide absorption
b) Rivers have become less acidic
c) Acidity has remained the same
d) Acidity is unrelated to atmospheric conditions - What is a major factor in the Amazon River’s high flow rate?
a) Its width
b) Its source in high mountains and descent to sea level
c) Its short length
d) Its lack of sediment - What makes the question of river erosion speed complex?
a) It is influenced by multiple interrelated factors
b) It has a straightforward answer
c) Only one factor is important
d) Rivers do not erode rock
Answers:
- b) Type of rock, sediment load, water volume and speed, acidity
- b) Softer rocks, like sedimentary rocks, are more easily eroded
- b) By eroding sedimentary rocks under specific conditions
- a) It speeds up the erosion process by acting like sandpaper
- a) Larger volumes of water carry more sediment and have more energy for erosion
- b) It dissolves, turning into carbon dioxide and water
- b) Granite is harder and more resistant to erosion
- a) Rivers have become more acidic due to increased carbon dioxide absorption
- b) Its source in high mountains and descent to sea level
- a) It is influenced by multiple interrelated factors
Original Version:
Article:
How quickly does a river cut through rock? It depends on the type of rock, the material the water is carrying, the amount of water, the speed of the water, and the acidity of the water.
This is not a simple question. When we think about the erosive power of water we often think of the Grand Canyon. It is roughly 1,200 meters deep and is 2,000 meters deep at its deepest point. It was formed by the Colorado River, and it has taken the river about five or six million years to erode as far as it has. However, the Colorado River has only been able to erode as much as it has because of a few specific conditions that we can look at.
The most important thing when we talk about the speed at which a river can erode rock is the type of rock. The rock of the Grand Canyon is made up of different sedimentary rocks. The area that is now the Grand Canyon used to be under a shallow sea, and sedimentary rocks form at the bottom of a sea. They are made when pieces of other rocks, sand, dirt, and dead
animals and plants sink to the bottom of the sea and become compressed. The rock in the upper layers of the Grand Canyon is limestone and sandstone, which are not very strong rocks. They crumble and break down fairly easily, which is one reason why the Colorado River could cut through them so easily. If the plain that became the Grand Canyon had been made out of granite, we probably wouldn’t have a Grand Canyon. The river would have formed a lake until it found a different route to take. Softer rocks, like sandstone, are easily eroded. Harder rocks like granite and basalt are not eroded so easily. Also, rocks that are made of large grains, rather than smaller grains like sandstone, will hold together more effectively in the face of water. Rocks that are set down in layers, like sedimentary rocks, erode more easily. As do rocks that fracture easily. So, where a river has cut down through a plain, we can usually assume that it was a softer rock.
The next thing to consider is the type of sediment that the river carries. Water on its own cannot erode rock very quickly. It can erode rock by getting in cracks, but it is mainly the sediment that the river carries which is the real power of erosion. If a river is carrying lots of sand, or small pieces of rock, those act like sandpaper and gradually scrape off the rock on the edges and the bottom of the river. Once this process has started, there is more rough sediment in the river and the more the process continues. The Colorado River had lots of sand from the sandstone, which sped up the process.
The volume of the water is obviously a big factor as well. The more water that a river has, the more sediment it can carry, and the more it can erode the rocks around it. The larger the volume of water, as well, the larger the amount of energy that the river has. The Colorado River has a flow rate of 109,557 liters of water per second. This is far lower than it was when the river eroded the Grand Canyon because the river has been diverted for irrigation purposes. The river with the highest flow rate in the world is the Amazon River, which has a flow rate of 220,000,000 liters of water per second. This speed is generated because of the amount of water that feeds into the river, but also because of the descent of the river. The Amazon River starts high in the mountains and ends up at sea level. This height difference creates a lot of speed as gravity pulls the water down. The same was true for the Colorado River, although the river has reduced most of that height difference through erosion. In the beginning, the tectonic plates shifted and pushed the river and the plains high up. This height gave the river a lot of speed, and it was able to cut through the soft rock fairly quickly. A large and steep river will have more power and be able to carry more sediment than a small river that only has a small difference in height between source and end.
The last thing is the acidity of the water. If water is more acidic, it can dissolve the minerals in rocks, rather than eroding them by carrying rough sediment. Some sedimentary rocks can react to acids. When limestone is exposed to acid, the calcium carbonate that makes up the rock becomes carbon dioxide and water, disappearing into the river. This acidity is increasing because the excess carbon dioxide we put into the atmosphere is absorbed by rivers, lowering their pH and making them more acidic. However, acidic rivers cannot erode the harder rocks.
So, the speed at which a river erodes through rock depends on the type of rock, the amount of sediment the river can carry, its speed, its volume, and how acidic it is. Even then, there are other variables, so it is a pretty impossible question.
Questions:
- What is the primary factor affecting how quickly a river can erode rock?
a) The river’s length
b) The type of rock
c) The presence of wildlife
d) The amount of sunlight - What type of rock forms the upper layers of the Grand Canyon?
a) Basalt
b) Granite
c) Limestone and sandstone
d) Marble - How does sediment in the river contribute to erosion?
a) By acting like sandpaper and gradually scraping the rock
b) By slowing down the water flow
c) By dissolving in the water
d) By making the water clearer - What is the significance of the Colorado River’s flow rate?
a) It determines the river’s length
b) It influences the amount of sediment the river can carry and its erosive power
c) It has no impact on erosion
d) It only affects the river’s speed - How does the Amazon River’s elevation difference contribute to its flow rate?
a) It causes the river to slow down
b) It increases the river’s speed due to gravity
c) It makes the river flow uphill
d) It has no effect on the river’s speed - What happens when limestone is exposed to acidic water?
a) It turns into sand
b) It dissolves, forming carbon dioxide and water
c) It becomes harder
d) It changes color - Why might the Colorado River not have formed the Grand Canyon if the rock had been granite?
a) Granite is softer than sandstone
b) Granite is harder and more resistant to erosion
c) Granite is only found in mountains
d) Granite dissolves in acidic water - How does the volume of water in a river affect erosion?
a) Larger volumes allow the river to carry more sediment and erode more effectively
b) Smaller volumes increase erosion
c) Volume has no impact on erosion
d) Volume only affects the river’s width - What is the effect of increased acidity in rivers?
a) It enhances the erosion of softer rocks like limestone
b) It has no effect on erosion
c) It slows down the erosion process
d) It makes the water clearer - Why is the question of how quickly a river can erode rock complex?
a) Because it depends on multiple interrelated factors
b) Because it has a simple answer
c) Because only one factor is important
d) Because rivers do not erode rock
Answers:
- b) The type of rock
- c) Limestone and sandstone
- a) By acting like sandpaper and gradually scraping the rock
- b) It influences the amount of sediment the river can carry and its erosive power
- b) It increases the river’s speed due to gravity
- b) It dissolves, forming carbon dioxide and water
- b) Granite is harder and more resistant to erosion
- a) Larger volumes allow the river to carry more sediment and erode more effectively
- a) It enhances the erosion of softer rocks like limestone
- a) Because it depends on multiple interrelated factors
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