VIRGINIA BARRIER ISLAND BACKGROUND

Virginia's barrier islands are part of a barrier island chain extending 2,700 miles from Maine to

Texas. These thin strips of sand provide valuable habitat for wildlife, protect the mainland from

the storm-driven fury of the ocean, and attract thousands of vacationers in the summer. For these

varied reasons, the barrier islands of Virginia are important natural resources. If improperly

managed, these islands could be lost; therefore, they are an ecosystem that deserve our attention.

The Islands and Their Location

Virginia's barrier island system is composed of 13 islands stretching 75 miles along the

oceanside of the Eastern Shore. The southernmost island is Fisherman, at the mouth of the

Chesapeake Bay. Fisherman Island is the smallest of the barrier islands, only 1 mile in length.

Although crossed by the Chesapeake Bay Bridge Tunnel, the island is not generally open to

visitors. It is a national wildlife refuge managed for the benefit of nesting shorebirds that spend

the spring and summer there.

Smith, Myrtle, and Ship Shoal islands are the next three islands to the north of Fisherman. They

are owned by The Nature Conservancy, a private conservation organization. As part of the

Conservancy's Virginia Coast Reserve, these islands are maintained as undeveloped natural

areas. Although there are some restrictions, the islands are open to the public. Access is not easy,

however, because the islands are not connected to the mainland and the only way to get to them

is by boat. The purpose of keeping these areas undeveloped and of limiting public access is to

preserve a natural beach system for future generations to enjoy.

Wreck Island is owned by the Virginia Division of Parks. It is also maintained as an undeveloped

natural area with limited public access.

To the north of Wreck Island are Cobb, Hog, and Parramore islands. They are natural areas in the

Virginia Coast Reserve. These islands at one time had thriving communities, but were

abandoned when shoreline erosion began to take its toll. Domestic animals such as goats and

cattle, left behind by the residents, survived in the wild on the islands. Many of these animals

were finally rounded up and removed to the mainland by the Nature Conservancy. The domestic

animals were disturbing the natural habitats and native animal species on the islands.

In contrast to the islands of the Coast Reserve, Cedar is a privately owned island that has been

developed. Beach cottages line the oceanfront where grass-covered dunes would otherwise stand.

It resembles the resort beaches of the East Coast rather than its neighboring barrier islands.

Beyond Cedar Island is Metompkin, the northernmost island in the Virginia Coast Reserve. With

Metompkin, Parramore, Hog, Cobb, Ship Shoal, Myrtle, and Smith islands, the oceanfront

property managed by The Nature Conservancy totals 50 miles.

The other privately owned island in Virginia's chain is Assawoman Island. The Nature

Conservancy is working to purchase this island for the Coast Reserve.

Wallops Island is owned by the federal government and is used by NASA as a rocket-launching

area. Although a bridge to the mainland makes access possible, Wallops Island is off-limits to the

public because of the government activities there.

Assateague is the northernmost, longest, and probably the most well-known of the barrier

islands. It extends north to Ocean City, Maryland. Although 33 miles in length, only 14 miles lie

within Virginia's borders. The entire island is federally owned. Part of i t is designated a

national seashore. Most of the Virginia section is a national wildlife refuge. This

island is the most familiar to the public because it can be visited by car. The area is managed

with both the wildlife and the public in mind. The beaches, marshes, and woodlands that are

inhabited by a variety of flora and fauna are easily observed from .well-maintained trails

and roads.

Formation of the Islands

When and how did Virginia's barrier islands form? Scientists believe that the islands formed

within the last 18,000 years when the last Ice Age ended and sea level began to rise. They

propose several theories for the formation of the islands:

Beach ridges became islands when rising water broke through and flooded the area behind

them. The new islands remained above sea level by migrating westward as sea level

continued to rise.

Offshore sand bars became islands after being built up above sea level.

Spits became islands after being breached by storms.

It seems as if the barrier islands do not have a common origin; each island is unique. The islands

probably formed under a combination of conditions.

Present Morphology

However the barrier islands were first formed, they are all now shaped by winds, waves, and

currents. The wind sculpts dunes from sand deposited above the water line. Waves work the sand

at the beach face and are responsible for the onshore-offshore movement of sand. Gentle waves

push sand onshore, building up the beach and providing sand for the dunes. Rough storm waves

erode the beach, carrying sand offshore where it is stored as bars. When gentle conditions return,

the bars move back toward the beach. The longshore current is generated by the waves that break

on the beach at an angle. The current flows within the surf zone parallel to the beach and carries

sand suspended by the waves. Longshore transport of sand along the East Coast is generally to

the south.

As a result of the wind, wave, and current actions, Virginia's entire barrier island system

migrates south and west. Sand, transported by the longshore current, moves south through the

system barrier by barrier. Sand also moves west, pushed by the continually rising sea level.

Overwash during storms carries the sand to the backside of the islands, allowing them to migrate

to the west.

Valuable Coastal Buffers

Barrier island systems are dynamic. Sand comes and goes, and the islands migrate; yet, they

maintain their identity above sea level. Because of their ability to withstand the power of the

ocean, barrier islands are valuable coastal buffers. They protect the mainland from the full

impact of storm winds, waves, and tides.

Valuable Coastal Habitats

Barrier islands provide habitats for wildlife. Because the islands have often been inaccessible to

man, the animals have been left undisturbed, which is particularly important during nesting

season. A walk across an island will take you through several habitats:

1. Beach

The beach is not an easy place to live. It can be quite hot during the day and cold at night. The

waves stir the sand, preventing rooted plants from growing. Salt in the water and in the air has an

adverse effect on many organisms. To survive here, animals must protect themselves from the

waves and tolerate salt water. Mole crabs and coquina clams are well adapted to life here. Their

streamlined shapes allow them to burrow quickly when a wave approaches. Other creatures live

higher up on the beach away from the waves. They protect themselves from the heat by hiding

under debris or by being more active at night. Ghost crabs are common inhabitats of the beach at

the base of the dunes. Many animals visit the beach to feed. Gulls, terns, and shorebirds eat crabs

and fish, or scavenge debris. These birds also nest on the beach.

2. Dunes

The dunes are far enough from the water that they are not normally worked by waves; therefore,

rooted plants can grow there. In Virginia, the common dune grasses are sea oats and American

beach grass. More animals can live in the dunes where they are protected from the waves and salt

water and can find shade among the grasses. Insects dominate the animal community in the

dunes. On the backside of the dunes shrubs such as wax myrtle and live oak appear. Perching

birds and small mammals inhabit the shrub thicket.

3. Swales

Swales are low areas between dune lines on a barrier island. Swales are often filled with fresh

water, creating a pond habitat where freshwater plants and animals live. The ponds are important

sources of fresh water for the animals that live in an environment otherwise surrounded by salt

water.

4. Maritime Forest

The maritime forest grows behind the dunes and the shrub thicket. The trees need as much

protection from salt spray as possible. In Virginia, loblolly pines, live oak, yaupom holly, and

black cherry grow in the maritime forest.

5. Marsh

Marshes are found along the backside of barrier islands. They fringe the shoreline of the sounds

that separate the islands from the mainland. The marsh grasses such as big cordgrass and

saltmarsh cordgrass can take root in the quiet waters of the sound. The grass provives food and

protection for many small animals. About 95% of the commercial fish and shellfish species in

Virginia spend some part of their lives in a marsh.

Man's Influence on the Barrier Islands

The Indians used the barrier islands as places to gather food. They recognized the potential

hazards of living on the open coast and only made seasonal hunting trips to the islands. When the

colonists arrived in Virginia, they did not initially settle on the islands. They were used by pirates

as hide outs and staging areas for raids. People who needed to escape from the growing society

found refuge on the barrier islands. Eventually, small communities, often founded by victims of

shipwrecks, popped up on some of the islands. These early inhabitants recognized the dynamic

nature of the islands and would simply pick up and move if the settlement were threatened by the

encroaching beach. Many settlements were completely abandoned when residents moved back to

the mainland.

In more recent times, the barrier islands have been viewed as ideal vacation spots. As the pace of

daily life increased, people went looking for an escape. Barrier islands, offered not only peace

and quiet but a variety of recreational opportunities, the perfect place to build a vacation home.

But, there was a catch to all of this - beach migration. Barrier islands are not stable. They are in

dynamic equilibrium with the present set of wind, wave, and current conditions. Although an

island looks the same from day to day, it has actually moved. The movement is imperceptible in

the short term, but is very obvious year-to-year or after a storm. This movement is natural beach

migration, but, to the oceanfront landowner, it is beach erosion!

What does the landowner do? Suddenly finding the ocean at the doorstep, the landowner wants

to protect and preserve the home. Barrier island residents of the past would move inland or back

to the mainland, but this resident thinks he or she has too big an investment to abandon the

property. So, groins, bulkheads, or riprap are installed. These structures may provide temporary

relief for the immediate area, but they are not a long-term solution. In fact, is there any longterm

solution? Remember, the culprit behind beach migration is the continuing rise in sea level. So

far, man has been unable to halt this force.

Most attempts at stabilizing the barrier islands for the sake of private homes have come at the

expense of the islands themselves.. Structures placed on the beach and in the dunes for

stabilizing the sand interfere with the natural onshore-offshore and longshore movement of sand

that maintain the islands against the forces of the ocean. When that system is interfered with, the

result is often a net loss of sand. The island can no longer maintain its identity in a steadily rising

sea and begins to disappear.

Developers see the islands as prime oceanfront property for resort and residential development.

Conservationists see the islands as unique biological and geological systems that should be left in

their natural state. How should the barrier islands of Virginia be managed?

Cross-section of a Barrier Island

Beaches, Sand, and Currents

The United States coast from New Jersey to Florida has many sandy beaches. But these

beaches are not all alike. Where wave action against the beach is heavy, the sar.d grains are

large. The beach itself slopes sharply into the sea. Less exposed beaches tend to have wide,

shallow shores with gentle slopes.

The most common mineral in sandy beaches is quartz, which comes from Inland on the

continent. Rock fragments are eroded away by rivers and carried down to the ocean. When these

pieces of rock reach the ocean, they are pounded into tiny grains by the movement of waves

against the shore. Other sources of materials for sand are rock outcroppings along the shore and

the shells of marine animals. Along the coast of North Carolina, for example, as much as 10% of

the beach materials are ground-up shells. Farther south the sands are made from weathered rocks

carried by rivers from the Appalachian Mountains. Still farther south the eastern beeches of

Florida can be almost pure quartz or quartz mixed with shell and coral.

Some of the most beautiful and valued beaches in

this region are on barrier islands. These are islands

of sand built up by the ocean and parallel to the

mainland. Barrier islands are formed along gently

sloping sandy coasts where the water remains

shallow far from the shore. Their name comes from

the fact that these stretches of sand are between the

ocean and the mainland. Figure A shows barrier

islands, the lagoon behind, their inlets, and a river

that empties into the lagoon.

Once formed, barrier islands are far from

permanent. Giant winter storms with their huge

waves can form new inlets or close older ones. During these storms, lave amounts of sand can be

dug from one place and deposited elsewhere along the beach. Even during the calmer weather of

summer, the ever-present surf is constantly reshaping the islands. Breaking waves carry sand

wish them as they run back into the sea. Longshore currents pick up this sand and move it down

the coast Since the Longshore Currents in this area usually move southward, they are slowly

carrying the barrier islands in that direction. Where there is an arm of land into the ocean or an

Inlet, sand is deposited on the north side and eroded away on the south side. This constant

migration of sand can cause entire sections of beach to disappear or the mouths of inlets to move

as much as 25 meters a year.

Because barrier islands are such splendid areas, many

people want to live and work on them. To do so, they try

to change the Island to fit their needs. Figure B shows

how the people who live In Fishville plan to change Blue

Inlet. They want to stop the migration of the inlet by

putting in jetties, or walls, along the inlet. Should this

plan be carried out? Look at the diagrams and the

information, and then answer the following questions.

BARRIER ISLAND STUDY

Objective

Analyze the natural and political forces that may influence the existence of barrier islands and

beaches

Background Information

Sea level was much lower during the last ice age, so deposits of sand on the continental shelf

were exposed to the action of wind and waves. Blown by the wind and moved toward shore by

the waves, the sand was piled up into large dunes. Submerged sandbars broke the surface and

moved toward shore as barrier islands. Some merged with the mainland while others formed

islands offshore.

Severe storms cause 'washover' on the barrier islands carrying sand into the bays on the landward

side. As sand is removed from the ocean and deposited into the bay, the island migrates slowly

landward.

Barrier islands also move parallel to the coast due to the longshore currents, in the direction that

the current is moving. One side of the barrier builds up while the other is eroded-both due- to the

movement of the long shore currents.

Vocabulary

Shoals – submerged sandbars

Lagoon – quiet body of water separating barrier islands from the mainland

Longshore current – current moving parallel to the shore caused by waves striking the beach at

an angle

Materials

Student copies of Barrier Island Study Map of Virginia’s Eastern Shore

Procedure

A. Using the background information and the map provided, answer the following questions:

1. Why are the Virginia barrier islands a valuable natural resource

2. Are all barrier islands formed in the same manner?

3. What shapes the barrier islands today?

4. Where does the Virginia’s barrier island migrate?

5. Label the missing parts of a beach in diagram 1. Then label the different zones in

diagram 2.

6. What are 2 reasons that barrier islands are so valuable?

7. Explain your trip over a barrier island starting at the beach and working your way bact

into the bay.

8. What is the most common mineral in a sandy beach?

9. How far can an inlet move each year? Why?

10. Complete the analysis questions. Yes you have to think- these may be your opinion!

Analysis

1. How does the Blue River contribute to the formation of barrier islands?

2. Why do you think people at Fishville are concerned about the movement of Blue inlet?

3. If you were the State Park Director how would you react to the plan? Why?

4. If you were in charge of the Coast Guard Station explain how would you react to the plan?