Table of Contents

WHAT IS THE DEPARTMENT OF THE INTERIOR AND THE MINERALS MANAGEMENT SERVICE?......1

WHAT IS INTERMAR AND WHY IS ITS WORK IMPORTANT? ....................................................................................1

WHAT IS SAND AND GRAVEL?......................................................................................................................2

WHY DO WE NEED SAND AND GRAVEL? ....................................................................................................3

WHAT IS A BEACH?.........................................................................................................................................5

WHAT IS EROSION? ........................................................................................................................................7

TYPES OF EROSION:..........................................................................................................................................7

Water Erosion .............................................................................................................................................7

Glacial Erosion............................................................................................................................................8

Wind Erosion...............................................................................................................................................8

Coastal Erosion...........................................................................................................................................8

WHAT CAUSES COASTAL EROSION? ..........................................................................................................9

WHAT CAN BE DONE TO RESTORE BEACHES AND CONTROL EROSION ................................................................9

STUDENT ACTIVITIES: BEACH PROFILING AND BEACH EROSION ......................................................11

EXAMINE SAMPLES OF BEACH SAND - PRIMARY.................................................................................................11

MAKE A BEACH PROFILE - PRIMARY.................................................................................................................11

ANALYZE GRAIN TYPES - PRIMARY ..................................................................................................................12

DO A SAND SIZE ANALYSIS - PRIMARY .............................................................................................................12

EXERCISE: ANALYZING SEDIMENT SIZE DISTRIBUTION - SECONDARY ...............................................................13

WHAT ENVIRONMENTAL CHALLENGES DOES MMS FACE IN DEALING WITH SAND AND

GRAVEL/BEACH EROSION?.........................................................................................................................16

SHIPWRECKS ..................................................................................................................................................16

SEAFLOOR CREATURES...................................................................................................................................16

FISH ...............................................................................................................................................................17

EFFECTS TO WAVES........................................................................................................................................17

RECOMMENDED INTERNET SITES..............................................................................................................18

www.mms.gov
1

What is the Department of the Interior,

and the Minerals Management Service?

The Department of the Interior is the

Nation’s principal conservation

agency and has responsibility for

most of our nationally owned public

lands and natural resources. This

includes ensuring good use of our

land and water resources; protecting

our fish, wildlife, and biological

diversity; preserving the

environmental and cultural values of

our national parks; and historical

places, and providing for the

enjoyment of life through outdoor

recreation. The Department

assesses our energy and mineral

resources and works to ensure that

their development is in the best

interests of all our people. The

Department also has a major

responsibility to Native Americans

and for people who live in island

territories under U.S. administration.

The Minerals Management Service

(MMS) is part of the Department of

the Interior. The MMS manages the

mineral resources located offshore

and collects revenue from the

minerals developed from offshore

and onshore Federal and Indian

lands and distributes those revenues

to states, Native Americans and to

the U.S. treasury.

What is Intermar and Why is its

Work Important?

Intermar (International Activities and

Marine Minerals) is a program within

the MMS that helps states who need

sand for their coasts. Intermar’s job

is to help the states find the sand on

the ocean floor to place on beaches

when storms and hurricanes destroy

them. We call this beach

nourishment. The sand along the

state’s coastlines out to 3 miles is

state property and can be used by

the states to put sand on the beach. 

When there is not enough sand in

state waters, then the state comes 

to Intermar to get sand for their

beaches. The MMS has

responsibility for the sand beyond 3

miles from a state’s coast and this is

known as the Outer Continental

Shelf (OCS). As more sand is

needed, we will use more OCS sand.

Most beaches need 1 to 2 million

cubic yards for one beach

nourishment project. The MMS has

provided over 14,600,000 cubic

yards of OCS sand to coastal states.

The communities whose beaches

have been destroyed by erosion or

storms write to Intermar to start a

sand project. Intermar makes sure

the environment is protected when
2

states receive sand for their

beaches. Intermar has done dozens

of scientific studies to find sand in

federal waters beyond 3 miles in the

ocean.

WHAT IS SAND AND GRAVEL?

Sand is a small rock fragment

commonly made up of quartz (beach

sand). Sand comes from the

weathering of rock fragments by

wind and water. 

Silt is a fine rock fragment smaller

than sand and larger than clay. This

is the smallest sand size visible to

the human eye.

Gravel consists of loose rock

fragments that are generally larger

than sand fragments - usually 1⁄2 inch

in length.

This is Surfside Beach, South Carolina before

it was nourished with sand.

This is Surfside Beach, South Carolina after it

was nourished with sand.

The upper 3 circles show coarse, medium, and

fine grains that are well sorted (most sand grains

are about the same size). The lower circles show

poorly sorted grains (a mixture of grain sizes and

types including grains of gravel).
3

WHY DO WE NEED SAND AND GRAVEL?

Sand and gravel play an important

role in the quality of life for all

Americans. In the early years of our

country, sand was used to make

plaster, bricks, and mortar - the

cement that holds bricks in place.

Gravel was used for making

concrete and as a pavement for

early roads and streets. Sand is

highly resistant to weathering and is

the main ingredient used in mixing

concrete for the construction of our

nation’s buildings and highway

system as well as for nourishing our

beaches.

Before the middle 1800’s, all mining

and construction work was done with

hand tools and animal power. With

the advent of steam engines,

construction progressed more

quickly. Moving construction

materials to building sites was

difficult at first, limiting the amount of

construction that could be done.

Prior to use in construction, sand

and gravel must be processed.

Machines are also needed to haul

sand and gravel from a pit or quarry

to a processing plant where the

material is crushed, washed, and

sorted into various sizes. In some

cases, sand and gravel are dredged

from the bottom of lakes and rivers

and moved by barge to a processing

plant and storage site. Once the

materials are processed, they must

be delivered to a construction site or

factory where they will be used.

Today, about 85 percent of all sand

and gravel moves by truck; the rest

goes by railroad or barge. 

As technical methods for mining

improved and more sand and gravel

became available, more materials

could be made from

sand and gravel. The

development of highstrength concrete and

asphalt enabled us to

make bridges,

highways, and

buildings bigger than

ever. These new structures use

large amounts of sand and gravel.

Asphalt pavement is made up of

more than 90 percent of sand and

gravel and concrete is over 80

percent sand and gravel. Nearly

20,000 tons of sand, gravel, and

crushed rock are needed to build 1

mile of a four-lane highway, and an

average of 120 tons are required to

build a new house in the United

States. Most of this goes into

concrete for foundations; basement

walls and floors; bricks; blocks; and

pavement for driveways, sidewalks,

and parking areas. 

Sand and gravel is in other things

too - paint, paper, vinyl, plastics,

roofing materials, glass, wallboard,
4

linoleum flooring,

and carpeting. All

of these things

require significant

amounts of sand

and/or gravel. Most indoor plumbing

and wiring products

contain vinyl, which also

contains sand. Sand

and silt (material

smaller than sand

grains) are also used as

fillers in many products

we use everyday such

as toothpaste,

medicines, rubber, and cardboard.

Each American uses

about 21,000 pounds

or 10.5 tons of sand,

gravel, and crushed

rock each year. At

an average weight of

3,000 pounds per

cubic yard, this

amount of material

would equal a cube 6

feet square at the base and 6 feet

tall.

Another big use of sand is to restore

beaches. Parts of many beaches

are lost each year as severe storms

cause waves to pull the sand out so

far into the sea that it cannot return

to the beach. When beaches lose

large amounts of their sand, they

become prone to breaching (when

the sea creates an inlet across the

beach) and are then unable to

protect the land and property behind

the beach. To fix this situation,

beaches must be nourished with new

sand to maintain their proper width. 

Here is a list of things from our

everyday life that contain sand and

gravel to give you an idea of how

important they are:

1. water glass or glass bottle

2. piece of asphalt pavement (look

for a pothole in a street - with

parent - there are usually small

pieces of pavement)

3. piece of asphalt shingle

(hardware store)

4. piece of concrete

5. piece of vinyl plastic or carpeting

6. Tums or a Rolaids pill

7. toothpaste

8. bottle of acrylic paint
5

WHAT IS A BEACH?

Beaches are made up of sand at the

edge of a body of water. Beach

sand comes from streams and rivers

that bring eroded materials to the

shore and from waves that

constantly hit the shoreline.

Beaches range in length from small

ones on lakes and rivers to ones

hundreds of miles long, like on the

Atlantic coast of the U.S. The width

of beaches ranges from a few feet

on rocky coasts to hundreds of feet

on some flat, low-lying coastlines. 

Beach length and width depend

upon sediment (mineral grains

deposited by water or air), its supply

(where its coming from), and its

stability (ability of the coast to

withstand erosion). If large amounts

of sediment are available and wave

energy (power of the waves) remains

low, a wide beach will form. The

beach will maintain its shape and

size if sediment supply and wave

energy remain about equal. 

The sediment that makes up a beach

can vary from large pebbles and

rocks to fine sand and even mud.

Many beaches in warm climates are

made from pieces of coral and shell

from nearby reefs. If sediments are

rapidly brought to the beach, such as

from the collapse of cliffs, the beach

will consist mainly of rock and gravel.

When sediments are brought slowly

to the shore and have more time to

break down into smaller pieces, a

sandy or muddy beach will form.

The color of a beach also depends

on the sediment supply. White sand

beaches are usually made of coral

and shell. Tan, brown, and gray

beaches are made from rivertransported sand or the erosion of

sandy cliffs. Beaches can even have

unusual colors such as the black and

green beaches in Hawaii (from

volcano sediments), orange and

yellow (from colored quartz and

clays), and pink (from pink 

Goat Island beach near Leigh, New Zealand.

The sand on this beach is made up of rock

and shell fragments.
6

coral). There are also beaches with

gold (Nome, Alaska), tin ore

(Indonesia), and diamonds (Namibia

and South Africa) sediments.

Pakiri Beach near Hahei, New Zealand. The

sand consists of coarse quartz, with a few

shell fragments.

This is a famous surfing beach at Raglan, New

Zealand. The beach consists of rocks and

boulders.

This is a picture of a beach that has many

shells. This occurs in sheltered places,

bordered by muddy bottoms. The shells can

be washed up easily.
7

WHAT IS EROSION?

Erosion is a natural process by

which rock and soil are broken loose

from the earth's surface at one

location and moved to another.

Erosion changes land by wearing

down mountains, moving shorelines,

filling in valleys, and making rivers

appear and disappear. It is usually a

slow process occurring over

thousands or millions of years. But

unusually large storms and human

activities such as farming, mining

and construction can speed up

erosion.

Erosion begins with a process called

weathering. The causes of

weathering include chemicals; living

organisms; the movement of air, ice,

and water; and heat from the sun.

These are called environmental

factors. In this process,

environmental factors break rock and

soil into smaller pieces and loosen

them from the earth’s surface. The

biggest cause of erosion is the

formation of ice. As water freezes, it

expands with great force. So when

water freezes inside tiny cracks in a

rock, it can break the rock apart.

After weathering has loosened

materials, they are moved to new

locations. For example, winds lift

particles from the earth's surface and

can carry them over great distances.

Glaciers transport materials trapped

inside their ice. Raindrops splash

against sloping land and move small

pieces of soil downhill. Water

currents carry materials down a

riverbed and out to sea. Ocean

waves crashing on the beach move

sand from one beach to another

beach, even those that are great

distances apart. 

Types of Erosion:

There are many different types of

erosion that occur in many different

places.

Water Erosion: Water plays an

important role in erosion by carrying

away material that has been

weathered and broken down. When

an area receives more water (in the

form of rain, melting snow, or ice)

than the ground can absorb, the

excess water flows to the lowest

level, carrying loose material with it.

Gentle slopes are subject to sheet

erosion (when rain washes away a

thin layer of top soil) and rill erosion,

(small closely spaced cracks caused

by running water cutting into surface

soil). In dry desert areas that have

little vegetation to absorb water,

runoff can leave a pattern of small

valleys and long narrow cracks

called gullies. 
8

Home threatened by coastal erosion.

Water can erode solid rock,

especially along streambeds when

the stones that are carried by the

water rub against other stones and

cause them to break apart. Every

year, rivers deposit about 3.5 million

tons of eroded land material into the

oceans.

Glacial Erosion: Glaciers are an

important part of erosion. Although a

glacier moves slowly, it does remove

all the loose material from the

surface over which it travels, leaving

bare rock surfaces when the ice

melts. Besides removing loose

material, glaciers actively erode the

solid rock over which they travel.

Rock fragments that become

embedded in the bottom and sides of

the moving ice mass act like giant

teeth grinding and scouring the

bedrock (solid rock usually

underlying soft sediment above) that

forms the walls and floors of

mountain valleys.

Wind Erosion: Wind is another

active agent of erosion, especially in

dry climates with little vegetation.

Wind blowing across bare land lifts

particles of sand and silt but leaves

behind larger pebbles and rocks.

Eventually, a surface layer of closely

packed stones, called a desert

pavement, is formed as the sand and

silt are removed. The removal of

large quantities of loose material is

called deflation. Deflation lowers the

landscape slowly, usually less than a

meter (3 ft) in a thousand years.

However, deflation can occur more

rapidly, as it did during the 1930’s in

the southern parts of the Great

Plains of the United States. This

was called the Dust Bowl. Winds

may sometimes deposit sand in

large piles known as sand dunes.

Coastal Erosion: When sand moves

away from beaches it is called

coastal erosion. Coastal erosion of

rocky cliffs and sandy beaches

results from the action of ocean

waves and currents. The constant

removal and replacement of sand

permanently changes the size and

shape of beaches. Sand may be

moved to dunes on the beach,

carried out to sea, or moved to

other beaches. This is especially

true during severe storms. In many

parts of the world, the loss of land

due to coastal erosion is a serious

problem because many buildings

and homes are built along the beach.
9

WHAT CAUSES COASTAL EROSION?

Coastal erosion results from the

beach interacting with the ocean.

The beach system is one that is

considered to be in dynamic

equilibrium. This means that sand is

moved from one location to another

but it does not leave the beach

areas. For example, winter storms,

which generate large waves, may

remove significant amounts of sand,

creating steep, narrow beaches. In

the summer, gentle waves return the

sand, widening beaches and

creating gentle slopes. 

It is the energy in the wave that

determines the size and the amount

of sand that will move and how far it

will go. The energy in the wave

depends on the speed of the wind,

how long the wave travels, and if

there is anything to block the wave

as it moves toward shore. Gentle

waves move fine sand, but stormgenerated waves can move rocks

and boulders. Materials picked up

from shoreline areas are deposited

wherever the water is slowed down.

Because there are so many things

that can affect coastal erosion

(including human activity, sea-level

rise, weather conditions and climate

change), sand movement will not be

consistent year after year.

Coastal erosion poses many

problems to coastal communities

because valuable property such as

businesses and homes can be

destroyed by waves if too much sand

is removed from the beach. Beach

erosion can also destroy the nesting

habitat of many threatened or

endangered sea turtles and birds.

Many coastal communities must

make decisions about whether to

and how to control erosion and

restore their beaches. 

What Can Be Done to Restore

Beaches and Control Erosion

When beaches shrink in size, it is

called the starving of sediment. This

happens when manmade features

like dams have been built to prevent

floods on rivers or other bodies of

water that stop new sand from

naturally nourishing the beach. 

One way to restore eroded beaches

is through beach nourishment. In a

A deck collapsing as a result of coastal

erosion.
10

typical beach nourishment project,

sand is collected from the ocean

bottom several miles from the shore

by a dredge, a large floating machine

used for scooping up sand and

gravel from the ocean floor. The

dredge then pipes the sand and

gravel to the beach. A mixture of

sand and water exits the pipe on the

beach, and as water drains away,

sand is left behind. Bulldozers move

this new sand on the beach until the

nourished beach matches the beach

before erosion. 

The rate at which new sand must be

added depends on how large the 

grains of sand are compared to that

of the original beach sand. The new

sand should be perfectly matched,

but this is almost impossible. If the

sand size is larger than the original

sand, the beach erodes more slowly.

If it is smaller, it erodes more quickly. 

Beach nourishment is a temporary

solution to the problem. If any

buildings and homes along the

beach are not moved out of the way

of the eroding beach, the beach will

have to be nourished again. The

amount of time between

nourishments depends on how fast

the beach is eroding. 

Nourishment sand provides three

important beneficial effects. 

1. Beach nourishment sand directly

protects the natural dune-bluffs (a

hill or ridge of windblown sand)

from wave attack by acting as a

buffer or protective zone between

the waves and the eroding natural

coast.

2. Beach nourishment reduces

erosion on nearby properties by

supplying sand to the regional

beach and sand bar system. Both

the beach nourishment site and

the shoreline benefit from the

added sand. 

3. Beach nourishment restores

beaches that continue to be used

for recreation and tourism.

Beach Nourishment Project at Patrick Air

Force Base, Florida 2001.

Offshore Dredge used to pump sand to

the Patrick Air Force Base, Florida 2001.
11

Student Activities: Beach Profiling

and Beach Erosion

Before nourishing a beach, a number

of things must be checked to see if

the project can be done correctly.

You need to find sand that matches

the size and color of the beach and

see if the shape of the original beach

can be maintained. You also need

to make sure that the environment

on the beach and the offshore shoals

(a mound of sediment on the ocean

floor that is higher than the area

around it) are protected. One of the

ways to study beach sand is to do a

grain size analysis (measuring grains

with a set of sieves with different

sized holes), to decide whether the

sand you want to use to nourish the

beach is about the same size as the

beach’s original sand. Finally, you

look at the grains under a

microscope to see the shape and

color. Once new sand is placed on

the beach, the beach is watched or

monitored to see if it is holding its

correct shape and if most of the sand

is staying on the beach.

Examine Samples of Beach Sand

– Primary

1. Using a magnifying glass, look at

the different sizes of sand grains.

Can you tell the difference in the

grain sizes?

2. Look at the color of the sand

grains. Grains that are clear and

glassy-looking grains are quartz.

Usually most yellowish-looking

grains are quartz also. Black and

dark brown grains are mostly iron

minerals or bits of other metals.

Light brown, tan, and pinkish

grains are usually a mineral called

Feldspar, which comes from

granite. Gray colored grains are

quartz or flint. See if there are

pieces of solid whiter grains,

which are parts of seashells or

other marine organisms. 

3. Place a handful of sand on a

sheet of white paper and make

the grains move around the paper

by tilting it from side to side. Note

how some of the similar colored

and similar sized grains seem to

stick together, such as the largest

grains and the darkest colored

grains. This is similar to what

happens when a wave hits the

beach and moves the sand

around.

Make a Beach Profile - Primary

To make a beach profile (a “picture”

of the area starting at the sand

dunes, moving across the beach,

ending at the sea floor) you will need

a string, a yardstick, and a small

level.
12

1. Start at the water’s edge and go

to where you see the vegetation

or the dune edge.

2. Using a cup or jar, gather

sediment samples from several

different sites in each of these

areas.

Analyze Grain Types - Primary

(This can also be done with sand

collected from a lake shore or

riverbed) 

1. Use a magnifying glass to

analyze grain types for several

small samples of beach sand you

collected.

2. Separate and count the number

of clear grains, light colored

grains, dark colored grains and

pieces of shell. These different

colors represent different types of

minerals in the grains.

Do a Sand Size Analysis -

Primary

The various sizes of grains that

make up a sand deposit can be

separated into groups of grains that

are about the same size. In this

way, sand can be described as being

of a certain average grain size,

which determines whether or not it

can be used for a given purpose. 

1. Start with as many different sizes

of kitchen strainers from coarse

size (largest openings) to fine

strainers (smallest). You can also

make paper sieves from cones

rolled by making pin pricks in a

large circle of printer paper.

Make large and small holes for

different size grains.

2. Weigh one of the samples you

took from one part of the beach,

or estimate volume with a

measuring cup.

3. Pass your sample through the

coarsest strainer, saving the

material that does not go through

in one jar.

4. Take the material that does go

through and put it through the

next smallest size strainer and so

on.

5. Save the last or final sample that

passes through the smallest size

strainer.

6. Weigh each of the separate grain

size groups or measure each in

the cup and then determine the

percentage of each size vs. the

whole sample. This is called a

sediment particle size distribution.
13

Exercise: Analyzing Sediment Size Distribution - Secondary

Required Materials:

Set of sieves (available from scientific supply stores)

Ruler

Scales (for weighing sediment) 

Collecting pan (plastic tray or baking pan)

Magnifying glass 

Paper Plates

Pencil and graph paper 

Several sediment samples (collected from the beach, river,

sandbox, etc.)

1. Stack the sieves inside the collecting pan from fine (smallest mesh) to coarse (largest mesh). If

done correctly, the sieve with the largest mesh size should be on top and the sieve with the

smallest mesh size should be on the bottom sitting inside the collecting pan. The collecting pan is

used to catch the very fine sizes of sediment including any silts and clays.

2. Using a scale or mass balance, measure and record the weight of the sediment sample in table 1.

Next, weight and record weight of an empty paper plate. Then pour the sample into the top of the

stacked sieves. Cover with a paper plate and shake the sieves gently for several minutes. Be

sure to hold the sieves snug as they may try to come apart during shaking. 

3. Take the nest of sieves apart and place them in order from coarsest to finest. Repeat the following

process for each sieve. Gently tilt one side of the sieve and tap the sides until all the sediment

moves to the bottom of the sieve. Carefully pour the sediment onto a paper plate by flipping the

sieve over and tapping the sides gently. Weigh the sediment. Record the weight of the sediment in

the box that matches the sieve size in table 1. 

4. Use the following to construct a chart that will show the percentage of each of the grain sizes to

the whole sample. This is called a Histogram. 

An example of a sand histogram is shown on page 15.

Table 1. Weight percent of grain sizes.

Grain

size

(mm)

Weight of

sample and

paper plate

Weight of

paper plate

Weight of total sample

(this number will be

the same for all)

Percentage

of total

0.05 - y x 100 =

0.10 - y x 100 =

0.25 - y x 100 =

0.50 - y x 100 =

1.0 - y x 100 =

2.0 - y *100 =
14

Construct a block diagram, or histogram on the graph below using the information you obtained from

sieving the sediment. The “x” axis represents the various sizes of the sediment, ranging form very fine

to very coarse. The “y” axis represents the weight in percent that you calculated above. For example,

if no sediment as found in the 0.10 mm sieve, then the percent of fine sediment in the entire sample

would be 0. If half the weight of the entire sample were found to be in the 0.25 mm sieve, then the

weight percent for medium sand would be 50%.

Table 2. Sediment Size Distribution Histogram

Wgt

%

100

90

80

70

60

50

40

30

20

10

00

0.05 mm 0.10 mm 0.25 mm 0.50 mm 1.0 mm 2.0 mm

Very Fine Fine Medium Coarse Very Coarse

Y-Axis

X-Axis

Topics for discussion:

Which sample shows the most sorting (more similar grain sizes)? 

Which sample shows the least sorting (more different size grains)?

Where might you find these types of sediments? Think back to older versus younger sediment

discussion (previous page).
15

Sediment Size Distribution Analysis Example

Grain

size

(mm)

Weight of

sample

(in grams)

Weight of

paper plate

(in grams)

Weight of

sample

(in grams)

Weight of

total

sample

(in grams)

Percentage of

total

0.05 2.2 - 0.2 2.0 y 22 x 100 = 9.0

0.10 5.2 - 0.2 5.0 y 22 x 100 = 23.0

0.25 10.2 - 0.2 10.0 y 22 x 100 = 45.0

0.50 3.2 - 0.2 3.0 y 22 x 100 = 14.0

1.0 2.2 - 0.2 2.0 y 22 x 100 = 9.0

2.0 0.2 - 0.2 0 y 22 x 100 = 0

Table 4. This is an example histogram of very well sorted sediment. This is the type of sediment you

might find on beaches such as Virginia Beach, VA, Ocean City, MD, or Huntington Beach, CA.

Wgt %

100

90

80

70

60

50

40

30

20

10

0.05 mm 0.10 mm 0.25 mm 0.50 mm 1.0 mm 2.0 mm

Very Fine Fine Medium Coarse Very Coarse

Y-Axis

X-Axis

Remember: Because of the energy generated by ocean waves, beach sands are typically better

sorted than river sands.
16

What Environmental Challenges Does MMS Face in

Dealing with Sand and Gravel/Beach Erosion?

 Shipwrecks

Some of the sand deposits being

considered for beach nourishment

contain shipwrecks. Some of these

wrecks are historic, others are not

but may be used by sport divers for

recreation and sport fishing. 

In order to make sure that dredging

for sand does not damage

shipwrecks, the MMS requires that

the area be surveyed to see if there

are any shipwrecks in the borrow

area, the area on the sea floor from

which the renourishment sand is

removed (usually a sand mound).

The sand material in the borrow

site is similar to the beach that is

being renourished. 

In order to protect valuable

shipwreck areas, the MMS may

establish a buffer zone in areas

where shipwrecks are known to be. 

Seafloor Creatures 

Creatures that live on and in the

sand on the ocean floor are the

most directly impacted by beach

nourishment activities. Many of

these communities rely on ridges,

long narrow, and low mounds of

sand, and shoals, shallow areas in

the ocean surrounded by deeper

water usually made up of sand, as

habitat. When dredging occurs on

the seafloor, the sandy bottom is

pulled through the dredge pipe

along with the creatures living

there. Most of the creatures either

cannot move or move too slowly to

escape the path of the dredge. If

they don’t escape they are

destroyed.

The type and size of the sediments

on the seafloor is important in

determining what creatures can

survive there. For instance, small

worms called polycheates tend to

reside in sediment that has fine

grains, but a type of shellfish called

a surfclam tends to like coarser

sand.

If dredging changes the types of

sediments on the seafloor

significantly, the creatures that live

in that area will change. Since

these creatures are a food source

for fish, the types of fish feeding in

that area may also change. 

The MMS always conducts sand

surveys to see what kinds of

creatures live in the area and sets

limits on how deep a dredge can

dig. We do this to help make sure

that seafloor creatures that move

back into the area will tend to be
17

the same type as those before the

dredging, because the area is not

significantly changed. 

 Fish

Another issue that MMS must

consider and study is the impact of 

dredging on fish and fishermen.

Sand shoals that are used for

beach restoration tend to be

favorite feeding places for fish as

well. Fish use the shoals as

sources of food, feeding on

creatures that live on the shoal.

They use the shoal for protection

and as a place to stay during winter

months when water temperatures

drop and storms are more frequent.

They also use the shoal to lay their

eggs. Since dredging removes part

of the shoal, fish populations can

decrease.

One way to address this problem is

to make sure that the dredging

leaves the shape of the shoal the

same. This helps to make sure that

the shoal can still be used by fish

as a feeding and resting place, as

well as a place to lay eggs. 

Effects to Waves

Another important effect of dredging

that MMS must study is deciding

whether or not dredging an offshore

shoal will increase erosion along the

shore. If it does, then dredging in

that area will only make the erosion

worse. However, for the most part,

OCS sand deposits are too far

offshore to cause a change in wave

patterns that would cause additional

erosion at the coastline. 
18

Recommended Internet Sites

The following is a list of internet sites that have information about sand, beaches, and beachrelated organizations.

www.mms.gov The U.S. Department of the Interior Minerals Management Service 

www.geology.com Great site to begin to learn about geology 

www.usgs.gov The U.S Geological Survey

www.fossilguy.com An interesting site about beaches and fossils in southern Maryland

and other areas 

www.usace.gov The U.S. Army Corps of Engineers

www.geosociety.org The Geological Society of America

www.assg.org The American Association of State Geologists

www.agiweb.org American Geological Institute

www.asce.org American Society of Civil Engineers

www.sme.org Society of Mining Engineers

www.noaa.gov National Oceanic and Atmospheric Administration

www.worlddredging.com World Dredging Magazine

www.esri.com Environmental System Research Institute (GIS and ArcGIS)

www.csc.noaa.gov Coastal Services Center

www.coprinstitute.org Coasts, Oceans, Ports & Rivers Institute of the American

 Society of Civil Engineers

www.geoinstitute.org The Geoinstitute of the American Society of Civil Engineers

www.aeg.org Association of Engineering Geologists

www.asbpa.org American Shore & Beach Preservation Association