Question 1

In the region immediately surrounding an isolated volcano,a ____________ drainage network is expected.
A)dendritic
B)radial
C)rectangular
D)trellis

Accepted Answer

Radial drainage networks are typical around isolated volcanoes since streams and rivers tend to flow radially away from a central peak or cone-shaped volcano. This pattern forms as streams and rivers follow the path of least resistance down slopes and valleys from the central peak. Dendritic, rectangular, and trellis drainage networks are not typically found in volcanic areas.

Question 2

Scientists have determined that Mars has actively flowing water-filled stream channels.

Accepted Answer

Scientists have not found actively flowing water on Mars; they have found evidence of past water flow and seasonal flows of briny water.

Question 3

Which has greater competence?
A)a small mountain stream
B)the Mississippi River

Accepted Answer

The Mississippi River is much larger and has a much greater volume of water compared to a small mountain stream. Additionally, the Mississippi River has more erosive power and is capable of carrying larger sediment and debris compared to a small mountain stream. Therefore, the Mississippi River has greater competence.

Question 4

The discharge of a river traveling through a humid region will typically ____________ downstream;the discharge of a river traveling through an arid region will typically ____________ downstream.
A)increase;increase
B)decrease;decrease
C)increase;decrease
D)decrease;increase

Accepted Answer

In a humid region, there is usually more rainfall, which leads to higher levels of soil moisture and groundwater. This extra water is continually fed into the river, causing the river's discharge to increase downstream.

On the other hand, in an arid region, there is minimal rainfall, and water is either quickly evaporated or absorbed into the soil. As a result, there is less water available to feed into the river, leading to a decrease in discharge downstream.

Question 5

All flowing water on the continents' surfaces is confined to stream channels.

Accepted Answer

Flooding can cause water to flow over land and outside of stream channels. Additionally, some water may collect in small depressions or swamps on the continent's surfaces.

Question 6

The slope of a stream surface measured between two points along its course is the ____________.
A)base level
B)floodplain
C)gradient
D)thalweg

Accepted Answer

The slope of a stream surface measured between two points along its course is known as the gradient. This is the change in elevation of the surface divided by the distance between the two points. A and B are not correct because they refer to different aspects of a stream. Base level refers to the lowest point a stream can erode to, while a floodplain is the flat area next to a stream where water overflows during floods. Thalweg refers to the deepest part of a stream channel.

Question 7

The deepest part of the channel,where the stream flows fastest,is the ____________.
A)base level
B)floodplain
C)stream gradient
D)thalweg

Accepted Answer

Thalweg refers to the deepest and fastest part of a stream channel, which is typically where the main flow of the stream is concentrated. Base level refers to the lowest point to which a stream can erode its channel, floodplain refers to the flat area adjacent to a stream channel that is subject to periodic flooding, and stream gradient refers to the steepness of the channel slope.

Question 8

The primary stream fed by tributaries within a drainage basin is termed a ____________.
A)lead stream
B)trunk stream
C)taproot stream
D)pirate stream

Accepted Answer

The primary stream fed by tributaries within a drainage basin is referred to as a trunk stream. This is because it serves as the main channel that integrates the water resources of smaller streams that flow into it. A lead stream is not a recognized term in the field of hydrology, while taproot stream and pirate stream are also not commonly used terms.

Question 9

In uniform sediments with a relatively constant slope at the surface,a ____________ drainage network is expected.
A)dendritic
B)radial
C)rectangular
D)trellis

Accepted Answer

Dendritic drainage patterns are formed on relatively flat or uniformly sloping terrain with no prominent control exerted by the underlying geological structure. Therefore, in uniform sediments with a relatively constant slope, dendritic drainage is the most likely pattern to form. Radial drainage is associated with cones or domes, rectangular drainage is common in areas with jointed or fractured bedrock and trellis drainage is typical of folded and dipping sedimentary strata.

Question 10

In a region with prominent orthogonal sets of joints,a ____________ drainage network is expected.
A)dendritic
B)radial
C)rectangular
D)trellis

Accepted Answer

In regions with prominent orthogonal sets of joints, a rectangular drainage network is expected because the rivers and streams tend to follow the paths of least resistance, which are often the fractures or joints in the rock. These joints typically intersect at right angles, leading to a rectangular pattern in the drainage network.

Question 11

The stream gradient of most rivers ____________.
A)is greater near the source than near the mouth
B)is greater near the mouth than near the source
C)does not change significantly as the river flows downstream
D)is greater for a meandering stream than for any other type

Accepted Answer

The stream gradient of most rivers is greater near the source than near the mouth, as the velocity of water is higher at the source of the river, resulting in a steeper gradient. As the river flows downstream, the gradient gradually decreases due to the reduction in velocity and the increase in the width and depth of the river channel.

Question 12

In a region characterized by a parallel series of ridges and valleys,a ____________ drainage network is expected.
A)dendritic
B)radial
C)rectangular
D)trellis

Accepted Answer

In regions with parallel ridges and valleys, a trellis drainage network is expected. This type of drainage network develops in areas with folded and faulted topography where there is a main river channel in the direction of the slope, and tributary streams that flow at right angles into the main channel, following the valleys between ridges. The resulting pattern resembles a garden trellis.

Question 13

Although the Nile River is longer,the Amazon River has the greatest discharge of any stream on Earth.

Accepted Answer

The Amazon River has the greatest discharge of any stream on Earth, despite being shorter than the Nile River.

Question 14

Ephemeral streams ____________.
A)consist of a series of intertwined channels that are overloaded with sediment
B)have flowing water either episodically or during a portion of the year
C)have a channel that is highly sinuous (curvy)
D)are those that divert flow from streams they have intersected through stream erosion.

Accepted Answer

Ephemeral streams have flowing water only during certain times of the year or during specific weather events, such as heavy rainfall. They may also be referred to as intermittent streams or seasonal streams.

Question 15

Ultimately,the base level of a stream valley can be no lower than ____________.
A)the average elevation of the continent on which it is found
B)sea level
C)the average elevation of the ocean basins

Accepted Answer

The base level of a stream valley refers to the lowest point to which water can flow. This is ultimately determined by the elevation of the body of water into which the stream or river empties, which is typically sea level. Therefore, choice B - sea level - is the correct answer. Choices A and C are incorrect, as they do not reflect the actual base level of a stream valley.

Question 16

As the velocity of flow decreases,____________.
A)flow tends to become more laminar
B)the maximum flow velocity decreases
C)suspended sediment starts to be deposited
D)All of the above are correct.

Accepted Answer

As the velocity of flow decreases, the flow tends to become more laminar, the maximum flow velocity decreases, and suspended sediment starts to be deposited.

Question 17

Which has greater capacity?
A)a small mountain stream
B)the Mississippi River

Accepted Answer

The Mississippi River has a greater capacity than a small mountain stream. The Mississippi River is one of the largest rivers in the world, with an average flow rate of 593,000 cubic feet per second. A small mountain stream, on the other hand, may only have a flow rate of a few hundred cubic feet per second at most. Therefore, the Mississippi River has a much greater capacity than a small mountain stream.

Question 18

All the water in rivers and streams arrives directly from rainfall runoff.

Accepted Answer

Not all water in rivers and streams comes directly from rainfall runoff; it can also come from sources like groundwater discharge, melting snow, and ice.

Question 19

The lowest elevation to which a stream can downcut is the ____________.
A)base level
B)floodplain
C)stream gradient
D)thalweg

Accepted Answer

Base level is the lowest elevation to which a stream can downcut as it represents the level where the stream ends and flows into another body of water or into the sea. The floodplain is the flat land adjacent to a stream that is flooded during high-water events. Stream gradient refers to the steepness of a stream channel, and thalweg is the deepest part of a stream channel.

Question 20

The sediment load of a stream consists of only those grains that are fine enough to stay in suspension.

Accepted Answer

The sediment load of a stream includes both suspended load (fine particles) and bed load (larger particles that roll or slide along the bottom).

Quiz 17: Streams and Floods: The Geology of Running Water

In the region immediately surrounding an isolated volcano,a ____________ drainage network is expected.

Scientists have determined that Mars has actively flowing water-filled stream channels.

Which has greater competence?

The discharge of a river traveling through a humid region will typically downstream;the discharge of a river traveling through an arid region will typically downstream.

All flowing water on the continents' surfaces is confined to stream channels.

The slope of a stream surface measured between two points along its course is the ____________.

The deepest part of the channel,where the stream flows fastest,is the ____________.

The primary stream fed by tributaries within a drainage basin is termed a ____________.

In uniform sediments with a relatively constant slope at the surface,a ____________ drainage network is expected.

In a region with prominent orthogonal sets of joints,a ____________ drainage network is expected.

The stream gradient of most rivers ____________.

In a region characterized by a parallel series of ridges and valleys,a ____________ drainage network is expected.

Although the Nile River is longer,the Amazon River has the greatest discharge of any stream on Earth.

Ephemeral streams ____________.

Ultimately,the base level of a stream valley can be no lower than ____________.

As the velocity of flow decreases,____________.

Which has greater capacity?

All the water in rivers and streams arrives directly from rainfall runoff.

The lowest elevation to which a stream can downcut is the ____________.

The sediment load of a stream consists of only those grains that are fine enough to stay in suspension.