Chapter 5 and 6 - Weathering and Groundwater

Identify and define the three soil horizons.

*A Horizon* is the mineral matter mixed with some humus (roots and organic matter). *B Horizon* is the accumulation of clay transported above. *C Horizon* is partially altered parent material.

Compare and contrast the changes in gradient and discharge between a stream's headwaters and mouth.

*Gradient* is the slope of steepness of a stream channel. *Discharge* of a stream is the volume of water flowing past a certain point in each unit. Both gradient and discharge are stream flow velocity factors.

How do the effects of mechanical weathering on rock differ from the effects of chemical weathering.

*Mechanical Weathering* = smaller and same kinds of rocks. *Chemical Weathering* = new compounds.

Distinguish between mudflows and earthflows.

*Mudflows* are fast and *Mudslides* are slow.

Identify the two general types of stream valleys.

*Narrow Valleys* is a narrow V-shaped valley shows that the stream's primary work has been down-cutting toward base level. An example of a narrow valley is the Youthful River. Features in narrow valleys include rapids and waterfalls. *Wide Valleys* are streams that is near base level. Downward erosion is less dominant. Stream energy is directed from side to side. The floodplain is the flat, low-lying portion of a stream valley subject to periodic flooding. A more mature river. Features often include meanders (curves), cutoffs, and oxbow lakes.

Distinguish between rockfalls and rockslides.

*Rockfalls* occurs when rock or rock fragments fall freely from the air (not touching Earth). *Rockslides* are rocks that move suddenly along a flat, inclined surface (touching Earth).

How much of the human body is water on average?

60%

Which layer in the soil profile has most of your organic material?

A Horizon

An artificial levee is a form of...

A flood control.

Predict the causes of floods and describe major flood control measures.

A flood discharge of a stream becomes so great that it exceeds the capacity of its channel and overflows its banks. Measures to control flooding includes artificial levees, flood control dams, and placing limits on floodplain development.

Can the following statement hold a little or a lot groundwater → *Loosely packed soil*

A lot

Can the following statement hold a little or a lot groundwater → *Soil with many pores*

A lot

Can the following statement hold a little or a lot groundwater → *Soil with particles of equal size*

A lot

List a negative effect on soil erosion.

A negative effect on soil erosion is a loss of cropland.

What type of mass movement occurs when rocks fall freely through the air?

A rockfall.

Meander

A stream in a broad, flat-bottomed valley that is near its base level often develops a course with many bends.

What is a tributary?

A stream that feeds another stream or lake.

How does a stream's gradient affect its velocity?

A stream's gradient affects its velocity when, velocity increases as gradient increases.

A rock caused by collisions with other rocks is called...

Abrasion

What type of mechanical weathering is commonly caused by wind-carried sand?

Abrasion

What human activity uses most water, worldwide?

Agriculture

Climates have the fastest rates of weathering...

Alternate between hot and cold.

Which of the following rocks is most likely to weather quickly?

An exposed rock on a slope.

Delta

Are an accumulation of sediment formed where a stream enters a lake or ocean.

Soil Horizon

Are zones or layers or layers of soil.

Any formation in which groundwater rises on its own under pressure is a(n)...

Artesian Well

Where is the water table located?

At the top of the zone of saturation.

Which horizon in the soil profile accumulates leached materials?

B Horizon

Which layer in the soil profile has most of your clay?

B Horizon

Which layer in the soil profile is also known as subsoil?

B Horizon

Which of the following is NOT a common agent of erosion?

Burrowing

In well-developed soil profiles, which horizon contains partially weathered parent material?

C Horizon

Uncontaminated rainwater is naturally acidic because of the presence of...

Carbon-dioxide

When a rock is exposed to chemical weathering, it...

Changes into one or more new compounds.

Chemical or Mechanical Weathering → *Acids from plant roots which break up rock.*

Chemical Weathering

Chemical or Mechanical Weathering → *Decaying plants dissolving in some of the minerals in rocks.*

Chemical Weathering

Chemical or Mechanical Weathering → *Feldspar mixing with acidic groundwater and producing clay minerals.*

Chemical Weathering

Chemical or Mechanical Weathering → *Formation of potholes in streets during severe winters.*

Chemical Weathering

Chemical or Mechanical Weathering → *Halite in rocks dissolving in water.*

Chemical Weathering

Chemical or Mechanical Weathering → *Limestone dissolved by carbonic acid.*

Chemical Weathering

Chemical or Mechanical Weathering → *Mosses growing on the surface of rocks, producing pits in the rocks.*

Chemical Weathering

Chemical or Mechanical Weathering → *The action of water, salt, and air on car fenders and panels.*

Chemical Weathering

Chemical or Mechanical Weathering → *The oxidation of minerals that contain iron.*

Chemical Weathering

Oxidation, hydrolysis, acid precipitation, and carbonation are examples of...

Chemical Weathering

Rusting is an example of what weathering process?

Chemical Weathering

What factor usually has the greatest effect on soil formation?

Climate

Which factor has the greatest effect on soil formation? Explain.

Climate because it influences rate, depth, and the type of weathering.

A gas changes into a liquid in a process called ____.

Condensation

Condensation, Precipitation, Melting, or Freezing → *Atmosphere to the Clouds*

Condensation

Pumping water from a well causes a(n)...

Cone of Depression

When air containing water vapor rises, it ____.

Cools

The slowest type of mass movement is known as...

Creep

Which vegetable has the highest content of water (96%)?

Cucumber

A ____ is something that happens over and over in the same way.

Cycle

Which layer in the soil profile represents the soil's parent rock?

D Horizon

Which of the following is an indirect method of flood control?

Dams

Which of these features forms at the end of a stream?

Deltas

When stream flow decreases to below the critical setting velocity of a certain size particle, ____ occurs.

Deposition

Volume of water flowing past a certain point in a given unit of time.

Discharge

Which of the following is NOT a cause of mechanical weathering?

Dissolving

The land area from which a stream gets its water is its ____.

Drainage Basin

The land area from which a stream gets its water is the ______.

Drainage Basin

A flow that moves relatively slowly―from about a millimeter per day to several meters per day.

Earthflow

Water flowing rapidly downhill has a high level of ______.

Energy

Which of the following are methods of water conversation?

Enforcing conversation laws.

Fast-moving streams and rivers ______ their beds.

Erode

By what process do streams and rivers move material?

Erosion

What is the name of the process by which the products of weathering are transported?

Erosion

Some of the water in a river will ______ when heated by the sun.

Evaporate

Earth's water cycle is balanced in that each year the average amount of precipitation occurs over Earth is equal to the amount of water that ____.

Evaporates

A liquid changes to a gas in a process called ____.

Evaporation

Condensation, Precipitation, Melting, or Freezing → *Ocean to the Atmosphere*

Evaporation

What process puts water vapor into the atmosphere?

Evaporation

Which process of the water cycle is a direct effect on the sun's energy?

Evaporation

Choose the two processes that cause each transitions → *Ocean to Clouds*

Evaporation and Condensation

What sequence of processes transports water from the ocean into a cloud?

Evaporation and Condensation

Which of the following are stages of the water cycle?

Evapotranspiration, condensation, and precipitation.

Which of the following is NOT a process of chemical weathering?

Exfoliation

True or False → *A soil that is muddy and sticky when wet contains a lot of sand.*

False

True or False → *A soil that is very coarse probably have a lot of clay in it.*

False

True or False → *A soil's texture refers to the shape of its particles.*

False

True or False → *Chemical weathering process physically break rock into smaller pieces but do not change its chemical composition.*

False

True or False → *Clay soils have a coarse texture.*

False

True or False → *From its headwaters to its mouth, a stream's gradient increases.*

False

True or False → *Rocks weather most rapidly in a hot, dry climate.*

False

True or False → *Soil has moved from one place where it was formed is called residual soil.*

False

True or False → *The chemical makeup of residual soil is different from that of its bedrock.*

False

True or False → *The most rapid and sudden type of down slope mass movement is known as creep.*

False

True or False → Human activities, such as farming, logging, and construction, have slowed down the amount of erosion that occurs today.*

False

A streams ____ is the flat valley floor onto which it overflows its banks during flooding.

Floodplain

The broad, flat valley floor cut by a stream is a ____.

Floodplain

Broad, flat valley floors carved by wandering streams are ______.

Floodplains

Water in shallow areas may be slowed down by rubbing or ______.

Friction

What type of mechanical weathering is most common high up in mountainous regions?

Frost Wedging

Which of the following is a form of mechanical weathering?

Frost Wedging

Which of the following weathering processes involves the constant freezing and thawing of water?

Frost Wedging

Roads in northern states such as Maine and Michigan need to be repaired more often than in roads in southern states such as Florida and Louisiana. What form of mechanical weathering could account for this?

Frost wedging occurs in the cracks in the road and then the road begin to crack and would need to be repaired.

Condensation is a change from a...

Gas to a Liquid

Where is the greatest percentage of Earth's fresh water located?

Glaciers and ice at the poles (2%)

Steepness of a stream channel.

Gradient

The slope of a stream is called its...

Gradient

The transfer of rock and soil downslope due to ____ is called mass movement.

Gravity

What force is responsible for all mass movements?

Gravity

Water that connects in the spaces between rock and soil particles called ____.

Groundwater

Compared to the past rates of soil erosion, the current rate is...

Higher

What type of climatic conditions is most likely to cause accelerated weathering? (Name the two types)

Hot and Humid

Explain how human activities affect the rate of soil erosion.

Human activities that affect the rate of soil erosion include the removal of natural vegetation. Such as farming, logging, and construction. Farming or agriculture has a big impact on soil erosion because they are also using a lot of soil and water to grow all kinds of crops and/or produce.

Decayed remains of organisms.

Humus

A common type of mechanical weathering that occurs in cold climates and is strong enough to split even huge boulders is called...

Ice Wedging

Temperature Change, Ice Wedging, or Root Action → *A stone wall begins to crumble after severe winters during which ice formed in its cracks.*

Ice Wedging

Temperature Change, Ice Wedging, or Root Action → *After a harsh winter, a street has many potholes.*

Ice Wedging

Which of the following does NOT involve a chemical weathering process that decomposes rock?

Ice Wedging

Which of the following is a type of mechanical weathering?

Ice Wedging

Which type of mechanical weathering occurs when water seeps into cracks in a rock and freezes?

Ice Wedging

Where is the majority of the Earth's fresh water stored?

In glaciers and ice caps.

In what climates is the weathering rate slowest?

In hot and dry climates.

Where is most of Earth's water located?

In the oceans.

Well

Is a hole bored into the zone of saturation.

Tributary

Is a stream that empties into another stream.

Soil Profile

Is a vertical section through all the soil horizons.

Artesian Well

Is any formation in which groundwater rises on its own under pressure.

Most erosion in a narrow V-shaped valley...

Is directed downwards.

Stalactites and stalagmites form when a cavern...

Is in the zone of aeration.

Soil

Is part of the regolith that supports the growth of planes.

Slump

Is the downward movement of a block of material along a curved surface.

Floodplain

Is the flat, low-lying portion of a stream valley subject to periodic flooding.

Regolith

Is the layer of rock and mineral fragments the covers most of Earth's island surface.

Gradient

Is the slope or steepness of a stream channel.

Creep

Is the slow, downhill movement of soil when regolith.

Zone of Saturation

Is the space where water fills all of the open spaces in sediment and rock.

Explain chemical weathering and give examples.

Is the transformation of rock into one or more new compounds. Water is the most important agent of chemical weathering. One type of weathering is the spheroidal weathering which is the corners of rock chemically weather more rapidly. It causes the corners and edges of rock to be more rounded.

Water Table

Is the upper level of the saturation zone of groundwater.

Discharge

Is the volume of water flowing past a certain point in a given unit of time.

Ground Water

Is the water within the zone of groundwater.

Chemical Weathering

Is then transformstion of rock into on elr more new compounds.

Surface Runoff

Is water, from snow-melt, or other sources, that flows over the land surface, and is a major component of the water cycle. A runoff occurs on surfaces before reaching a channel is also called overland flow.

What is the defining characteristic of a water cycle?

It has the same starting and end point.

What is the lowest point to which a stream can erode its channel?

Its base level.

What is the maximum load a stream can carry called?

Its capacity.

Why are leaking landfills and septic tanks a concern to people who use groundwater?

Leaking landfills and septic tanks concern people who use groundwater because they can enter the soil and pollute the groundwater that they are using to drink and where they get their water from.

Which of the following generally weathers most rapidly?

Limestone

If water vapor loses enough heat, it changes back into a ____.

Liquid

Evaporation is the change from a...

Liquid to a Gas

Freezing is the change from a...

Liquid to a Solid

Can the following statement hold a little or a lot groundwater → *Soil with few pores*

Little

Can the following statement hold a little or a lot groundwater → *Soil with particles of different sizes*

Little

Can the following statement hold a little or a lot groundwater → *Tightly packed soil*

Little

Classify and define mass movements.

Mass movement is the transfer of rock and soil down-slope due to gravity.

What is a stream's suspended load?

Material that is carried in suspension.

Streams are classified as young, ______, or old.

Mature

Youthful or Mature → *Meanders*

Mature

Youthful or Mature → *Nearly flat slope*

Mature

Youthful or Mature → *No waterfalls or rapids*

Mature

Youthful or Mature → *Oxbow lakes*

Mature

Youthful or Mature → *Slow-moving water*

Mature

A curve in the river formed by erosion is called a ____.

Meander

Fast-moving water erodes the side of a stream and forms a curve or ______.

Meander

What is a bend in a stream called?

Meander

Chemical or Mechanical Weathering → *A small rock falling from a cliff.*

Mechanical Weathering

Chemical or Mechanical Weathering → *Animal burrows dug in rock that let in water and air.*

Mechanical Weathering

Chemical or Mechanical Weathering → *Lifted sections of sidewalk along tree-lined streets.*

Mechanical Weathering

Chemical or Mechanical Weathering → *Repeated freezing and thawing of water that cracks rock.*

Mechanical Weathering

Chemical or Mechanical Weathering → *The wedging of tree roots along natural joints in granite outcrops.*

Mechanical Weathering

Chemical or Mechanical Weathering → *Tree roots cracking the concrete foundation of a house.*

Mechanical Weathering

Ice, plants, animals, gravity, running water, and wind are common agents of...

Mechanical Weathering

Condensation, Precipitation, Melting, or Freezing → *Glacier (river of ice) to a River*

Melting

The largest drainage basin in the United States is the river basin of the ______.

Mississippi

The largest drainage basin in the United States is that of the ____.

Mississippi River

Most of the rain that falls between the Rocky Mountains and the Appalachian Mountains flows into the ____.

Missouri and Ohio Rivers

Mudflow

Move quickly and carry a mixture of soil, rock, and water that has a consistency of wet concrete.

Earthflow

Move relatively slowly and carry clay-rich sediments.

A quickly moving mass of material that contains long amounts of water.

Mudflow

Mechanical Weathering

Occurs when physical forces break into smaller and smaller pieces without changing the rock's mineral composition.

Define mechanical weathering and give examples.

Occurs when physical forces break into smaller pieces without changing the rock's mineral composition. Break rock into smaller pieces by ice, plants, animal, gravity, running water, and wind. Types of Mechanical Weathering include frost wedging, unloading, and biological activity.

Rockfall

Occurs when rocks or rock fragments fall freely though the air.

Flood

Occurs when the discharge of a stream becomes so great that it exceeds the capacity of its channel and overflows its banks.

Which of the following contains the largest percentage of Earth's water?

Oceans

What is humus made up of?

Organic Material

Humus is mainly made up of...

Organic material.

Explain environment threats to water supplies.

Overuse and contamination threatens groundwater supplies in some areas. Sewage from septic tanks, farm wastes, or broken sewers. Also from all the trash or electronics (acids) laying around outside for many years can seep into the ground and get into out water pipes or groundwater and does not get filtered properly, then we are drinking water that is contaminated with acids.

What occurs when a rock is broken into smaller pieces without a change in the rock's mineral composition?

Physical Weathering

The air spaces between rock and soil particles is called ____.

Pores

Condensation, Precipitation, Melting, or Freezing → *Cloud to Snow*

Precipitation

Condensation, Precipitation, Melting, or Freezing → *Clouds to Soil*

Precipitation

The process by which water changes from a gas to a liquid is referred to as...

Precipitation

Water falls to Earth from the atmosphere is called ____.

Precipitation

Choose the two processes that cause each transitions → *Clouds to Glaciers*

Precipitation and Freeze

A river system begins to form in a given area when...

Precipitation exceeds evapotranspiration.

Which of the following minerals is most resistant to weathering?

Quartz

Which of the following minerals or rocks would be most resistant to weathering?

Quartz

Precipitation

Rain, snow, sleet, or hail - any kind of weather condition where something's falling from the sky.

One major cause of floods is ______.

Rapid spring snow melt.

A young stream may have white water ______.

Rapids

Which of the following would least likely be found in a wide valley?

Rapids

Exfoliation

Reduced pressure on igneous rock causes it to expand and allow slabs of outer rock to break off in layers.

A layer of rock and mineral fragments.

Regolith

Streams formed from runoff meet to form a ______.

River

When rock or rock fragments fall freely through the air.

Rockfall

Slides that include bedrock that move suddenly along a flat, inclined surface.

Rockslide

Temperature Change, Ice Wedging, or Root Action → *Cracks appear in a sidewalk near a tree.*

Root Action

Temperature Change, Ice Wedging, or Root Action → *Cracks develop between the bricks of an ancient stone ruin among the trees in a jungle.*

Root Action

The ____ of most plants get water from the upper levels of the soil.

Roots

What are five factors that determine the velocity of a stream?

Roughness, volume of water, slope, shape of the stream, and size of the stream.

Which of the following rocks would form the best aquifer?

Sandstone with high porosity and high permeability.

When pore spaces in the ground are holding as much water as they possibly can, the ground is ____.

Saturated

What are the factors that commonly trigger mass movements?

Saturation of surface materials with water, oversteeping of slopes, removal of vegetation, and earthquakes.

What other factors can trigger mass movements?

Saturation, over-steeping slope, removal of vegetation, and earthquakes trigger mass movements.

Talus

Sections of rock that are wedged loose may tumble into large piles, which typically form at the base of steep, rocky cliffs.

What is exfoliation?

Slabs of outer rock break off from unloading.

Rockslide

Slides that include segments of bedrock.

The downward movement of a block of material along a curved surface.

Slump

Part of the regolith that supports growth of plants.

Soil

The part of the later of rock and mineral fragments of Earth's surface that supports the growth of plants is known as...

Soil

Melting is the change from a...

Solid to a Liquid

A stream's ability to pick up and move material depends largely on its ____.

Speed or Velocity

A natural flow of water that reaches the surface of Earth is called a(n)...

Spring

What is the relationship between a spring (surface water) and the water table?

Springs can form where the table meets the ground surface.

How does slope affect the formation of soil.

Steep slopes has less soil, and flat ground has more soil.

Which fruit has the highest content of water (92%)?

Strawberries

RIvers are formed when smaller ______ come together.

Stream

Course that water in a stream follows.

Stream Channel

Which factor is most important in determining the erosive power of a stream?

Stream Velocity

Which of the following areas would be most likely to have a thick, well-developed soil?

Stream valley in warm area with abundant rainfall.

Water runoff forms small ____.

Streams

Temperature Change, Ice Wedging, or Root Action → *The outside of a rock peels off from repeated heating and cooling.*

Temperature Change

*Applying Concept:* Why must Earth's water cycle be balanced in order for the system to work?

The Earth's water cycle must be balanced in order for the system to work because it would cause floods or droughts if it is not balanced properly.

____ is the repeated movement of water between Earth's surface and the atmosphere.

The Water Cycle

Describe the ability of a stream to erode and transport material.

The ability of a stream to erode and transport materials is known as velocity which is rapidly of motion or operation; swiftness; speed and the rate of speed with which something happens; rapidly of action or reaction.

A watershed is...

The area drained by a river system.

How does a river's speed affect how much it erodes its channel?

The faster the river, the faster it erodes its channel.

What is the force behind mass movement.

The force behind mass movement is gravity.

What are the main causes of floods?

The main causes of floods are rapid spring snowmelt or heavy rain.

Recognize the major components of soil and list the most important factors in soil formation.

The main components of soil are mineral matter (or broken-down rock), humus (is the decayed remains of organisms), water, and air. The most important factors in soil formation is parent material, time, climate, organisms, and slope.

Frost Wedging

The mechanical breakup of rock caused by the expansion of freezing water in cracks and crevices.

Infiltration

The movement of surface water into rock or soil through cracks and pore spaces.

Condensation

The process by which water vapor in the air is changed into liquid water

Evaporation

The process of turning from liquid into water vapor.

*Relating Cause and Effect:* How would a reduction in friction in a stream channel affect the stream's velocity?

The reduction in friction in a stream channel affect the stream's velocity because the speed of the water would increase.

Transpiration

The release of water in the atmosphere from plants through the ground.

When a rock's exposure to weathering agents increases...

The rock weathers faster.

Identify the factors that trigger mass movements.

The transfer of rock and soil down-slope due to gravity is called mass movement. Among the factors that commonly trigger mass movement are saturation of surface materials with water, over-steeping of slopes, removal of vegetation, and earthquakes is how human activities affects the rate of soil erosion.

Mass Movement

The transfer of rock and soil downslope due to gravity.

Explain how to water cycle circulates Earth's water supply in an unending circle.

The water cycle describes the continuous movement of water on, above, and below the surface of Earth. The water cycle moves from one reservoir to another, such as from river to ocean to the atmosphere, by the physical process of evaporation, condensation, precipitation, infiltration, and surface runoff. In doing so, the water goes through different forms such as liquid, solid (ice) and water vapor.

*Applying Concepts:* A person drills a well into an area where there is a known aquifer underground. But the well doesn't produce water. What might be the cause of this problem? What does this person need to know about the water table in this area?

The well is not deep enough, above the water table. This person will need to dig deeper down.

*Applying Concepts:* A stream's discharge increases. Explain how this affects the stream.

This affects the stream because less water would slow the speed of the stream down.

How does water move from plants to the atmosphere?

Transpiration

Plants lose water through the stomata in their leaves in a process called ____.

Transpiration

A stream that flows into another larger stream is called a...

Tributary

True or False → *A stream's discharge increases between the headwaters and mouth of the stream.*

True

True or False → *In many regions of the world, soil is eroding faster than it is being formed.*

True

True or False → *Joints are often formed when the pressure on rock decreases.*

True

True or False → *Oxidation often produces a reddish soil.*

True

True or False → *Plants can cause both mechanical and chemical weathering.*

True

True or False → *Soil has four main components: mineral matter, humus, water, and air.*

True

True or False → *Steep slopes are often too dry to support plant growth.*

True

True or False → *The C horizon in a residual soil consist of partially weathered bedrock.*

True

True or False → *The chemical makeup of residual soil is the same as that of the bedrock which it lies.*

True

True or False → *The smallest particles in soil are clay.*

True

Identify the two factors that affect the rate of weathering.

Two factors that affect the rate of weathering is Rock Characteristics and Climate. *Rock Characteristics* are the mineral composition which is the type of rock and minerals and the physical features such as cracks in the rocks. *Climate* is the temperature and moisture are the most crucial factors and chemical weathering is the most effective in areas with high temperatures and abundant moisture.

What two processes are all landforms subject to?

Uplift and erosion.

What shape will a stream valley have if its primary work has been downward erosion cutting toward base level?

V-shaped

Distance that water travels in a period of time.

Velocity

*Predicting:* Erosion reduces the size of pebbles on the bottom of a stream channel. Which of the following would be most affected - the stream's competence, velocity, or discharge? Explain your answer.

Velocity, it would increase left friction.

What is the most important agent of chemical weathering?

Water

Evaporation, condensation, transpiration, and precipitation make up the ____.

Water Cycle

What term is used to describe the unending circulation of Earth's water supply?

Water Cycle

The upper layer of saturated rock is...

Water Table

The upper level of saturated rock is called the ____.

Water Table

When liquid water from oceans, lakes, and other bodies of water absorbs heat energy from the Sun, it changes into ____.

Water Vapor

Water Cycle

Water constantly moves among the oceans, the atmosphere, the solid Earth, and the biosphere. This unending circulation of Earth's water supply is known as the _______.

Heat speeds up most chemical reactions. Why then does chemical weathering happen slowly in hot deserts?

Water is the most important agent of chemical weathering, there is no water inside of a desert.

What is the name for the land that is drained by a river system?

Watershed

A hole dug below the water level in order to bring water to the surface is called a(n)...

Well

The ability of a stream to erode and transport material depends largely on its...

Width

How would you determine the texture of the soil in your area?

You would determine the texture of your soil in your area by looking at the particle sizes.

A stream that flows swiftly through a steep valley is a ____ stream.

Young

Youthful or Mature → *Fast-moving water*

Youthful

Youthful or Mature → *Narrow, V-shaped valleys*

Youthful

Youthful or Mature → *Rapids*

Youthful

Youthful or Mature → *Waterfalls*

Youthful

The aquifer zone that lies between the water table and Earth's surface is called the...

Zone of aeration