Experiencing the Ocean

Travelled to the National Seashore with friends on two separate journeys. The first was to Assateague Island Maryland, then to Assateague Island Virginia, and finally to Cape Hatteras Lighthouse in North Carolina. Returned the second time to Assateague Island in both Maryland and Virginia. Sharing my experiences, which I trust will make your heart smile.

BARRIER ISLANDS
Barrier Islands are long, narrow islands that form when a sandbar has built up enough to break through the water’s surface. Along the eastern coast in the Atlantic Ocean lie these long narrow islands built from sand. They lie parallel and close to the mainland, protecting it from the powerful forces of wind and water. These islands are constantly being shaped by accretion (sand building up to create new island structures), and erosion (waves, currents, tides, storms).  

Currents and storms work to continuously reshape the land. Longshore currents transport sand south along the coast. In the winter, sand is pulled from dunes and beaches depositing it into offshore sand bars thus reducing beach width. This process is reversed during milder summer weather, as gentler wave action acts to restore the shoreline. As land is lost on the front side of the island. it is usually gained on the back side. The combination of these processes continually moves the island southwest.

MOVEMENT OF THE WATER
Ventured a little beyond ankle depth with balance support from a friend. The moving waves and shifting sand beneath my feet felt like a vertigo-type sensation causing me to periodically look toward the beach to regain my balance. Interesting experience!

STORMS
The islands move southwest a few feet each year. This is caused by the ever changing actions of wind and water. The most powerful agents causing island rollover (landward migration due to large storms transporting sand from sea to land)  are the storms. Most storms have surface winds ranging from 39-73 mph. A severe storm surface winds of 74 mph or greater is deemed a hurricane. Storm-induced waves that exceed the height of the dune are called overwash. Sand is transported over top of the dune and deposited inland in large layers called overwash fans.
EXPERIENCE
Stand ankle deep in the water. a. Describe what you are experiencing. Include both the water and the sand. b. How does what you are experiencing relate to movement of water and sand during a storm? … My feet sank in the sand with water swirling around. It was amazing to experience the awesome power of the ocean even at only ankle deep. There was quite a difference based on wave heights. The shallower waves moved the sand around my feet. The higher waves caused sand to wash over my feet akin to overwash during a storm event. It is no wonder that storms cause so much change when their power is unleashed on the land.

ISLAND ROLLOVER
The islands move southwest a few feet each year. This is caused by the ever changing actions of wind and water. Barrier islands move and change in response to ocean waves and currents. Over long time scales, barrier islands move slowly landward. This landward migration is called barrier island rollover.
EXPERIENCE
Stand ankle deep in the water. a. Describe what you are experiencing. Include both the water and the sand. b. How does what you are experiencing relate to island rollover? … My feet sank in the sand with water swirling around. It was amazing to experience the awesome power of the ocean even at only ankle deep. As the water flowed toward land, the grains of sand also moved landward akin to island rollover.

LITTORAL TRANSPORT
The islands move southwest a few feet each year. This is caused by the ever changing actions of wind and water. This movement is due to oceanic drift caused when waves approach a beach at an angle (longshore currents) resulting in lateral movement of sediment (longshore drift). Littoral drift is the combination of longshore currents and longshore drift within the surf zone. This zone is the region of breaking waves responsible for 80%-90% of littoral transport.
EXPERIENCE
Stand ankle deep in the water. a. Describe what you are experiencing. Include both the water and the sand. b. How does what you are experiencing relate to the necessity of moving the Cape Hatteras lighthouse? … My feet sank in the sand with water swirling around. It was amazing to experience the awesome power of the ocean even at only ankle deep. I had to work at keeping my balance otherwise I would have been moved toward shore. (westward migration of the islands). The sand was continually shifting akin to littoral drift.

READING THE WATER
CUT – gap on sandbar perpendicular to the beach. This is where rip currents form.
GUT – depressions between sandbars which run parallel to the beach. 
HOLE – deeper than sandbar. Breaking wave is on edges not over the hole.
EXPERIENCE
Stand on the beach and read the water.
Located sandbars indicated by the various waves.

ADDITIONAL OCEAN TERMS
BARRIER SPITS – depositional formations cause by littoral drift.
BEACH – exposed sandbars that become emergent and are built up by swash and wind-carried sand.
SANDBAR aka OFFSHORE BAR – long, narrow  submerged or partly exposed ridge of sand or coarse sediment built by waves. 
SHOAL – accumulation of sediment generally less than 33′ below water level at low tide. These are formed by the same factors that produce offshore bars. The difference is the depth below the water.
SWASH –  turbulent layer of water that washes up on the beach after an incoming wave has broken.
UNDERTOW – occurs everywhere underneath shore-approaching waves.

BLOG … Wild and Free – Miracle on the Beach
EARTHCACHES … Habitats – Beach – MD – VA – NC
Thank you Mike (Earthcache Reviewer) for your encouragement
with the MD-VA-NC Man vs Nature series
that led to the inspiration for this Experiencing the Ocean blog.