Formation
Most beach sand comes from glacial erosion. Eroding forces break down rocks into smaller particles. In the past, during glaciation, glacial rivers transported sand to the coast. Today, headlands and cliffs are eroded and sand is formed. Looking at the colour of the sand can be a clue as to where the sand originates from. In Prince Edward Island it is easy to determine.
The sand is red as the red sandstone that is seen exposed everywhere along the coast. In Nova Scotia there are white beaches, whereas the beaches in northeastern Atlantic Canada are darker in colour. Sand is constantly on the move. In the summer, beaches are built and sandbars eroded; in the winter, the reverse happens. Wind and water sort the sand
Dunes are formed wherever large quantities of dry sand are exposed to wind. Dunes have a tendency to wander. Wandering dunes are called 'active dunes.' As they move they can even cover roads or buildings. When they are unstable, little vegetation grows on them. It is too difficult for plants to get established.
The 'foreshore' is the sloping portion of the beach between high and low tide. A 'berm' is nearly horizontal and is formed when the waves deposit sand. A storm berm can mark the highest limit of storm waves. Several berms can occur at spring and neap tide levels. The 'back beach' or 'backshore' is rarely touched by wave action and ends at the edge of the first dune.
The 'active dune' or 'primary dune' is the first dune. A 'swale' is the hollow between dunes, often close enough to the water table so that marsh plants or peatland plants can get established. Stagnant freshwater pools can develop. 'Fixed dunes' or 'secondary dunes' can follow, sometimes in great numbers. 'Blowouts' are holes in the dune scooped out by wind and/or water.
Physical Characteristics
Currents
Currents on the beach act as agents of erosion and rebuilding. They carry sand and nutrients from one spot to another. The shape of the beach front is influenced by different currents. The most common are longshore (along the beach) currents, refractive, and rip currents.
Ice
Unusually heavy winter ice cover can change or erode dunes and alter the shape of the beach, or it can protect the beach from the influence of wind and waves.
Freshwater
On the beach most freshwater percolates rapidly down into the substrate. Thus the surface is always dry. Evaporation on the surface can be rapid.
Ripples and dangerous currents
Ripples are a feature well known on beaches and sandflats. They are the result of an oscillation of the sand, created by wave action and tides. The ripple crests are transverse to the current direction. The 'drag' on the ocean bottom that can be felt by swimmers is caused by rip currents. They are narrow currents moving at right angles away from the beach, after having been heaved against the shore. They can pull swimmers out to the open ocean.
Salt
The salinity in the inundated area of the beach varies only slightly. In depressions at the beachfront, when sea-water collects, salinity can rise sharply as the water evaporates. Plants are constantly exposed to the wind. The wind carries salt spray and deposits it further inland on the plants. The exposure to salt prevents many organisms from living at the beach.
Sediment
Waves move and shift sand around to form a beach. The interaction of sediment and waves forms beaches. The interaction of sediment and wind forms dunes. Sediments are transported to different places by water and wind depending on their size and density. Sand shifts constantly. It can vary in colour dramatically, from the red beaches of Prince Edward Island to the almost white beaches of Nova Scotia. The colour of the sand can also affect the kinds of organisms that live on a beach, because they have to be camouflaged from their predators. Most organisms have some adaptability. Those that do not simply bury themselves.
Sand
Young (geologically speaking) sand usually consists of sharper particles not yet rounded off by wind and water as is the case with old sand. Airborne sand rounds more than water-borne sand. Fine sand is carried away easily and compresses well. There are few spaces between particles. Once they settle they do not shift as readily. Coarse sand stays behind and does not compress well. There is lots of airspace between particles for organisms to live in, but this sand shifts constantly. Irregularly shaped particles have large pore spaces in between and thus more surface area.
When creatures die the skeleton that remains is broken up. These parts consist mainly of calcium carbonate. Some sands consist mainly of calcium carbonate particles. Sand can be made of small particles originating from erosion of rocks through water, chemicals, and temperature. Quartz sand is the most common on the East Coast, a result of the breakdown of granite or sandstone.
Some sand particles 'sing' when blown over the beach by high winds. Singing sands are a feature of the Basin Head sand dune system in eastern Prince Edward Island.
Temperature
Along the beach shoreline the temperature changes with the tides and the seasons. Without shelter from plants the sand can get so hot that people cannot walk on the beach with their bare feet. Below the surface the sand becomes cold quickly. At night the sand cools off rapidly due to the lack of a protecting plant cover. On hot days the temperature can be high enough to coagulate blood proteins of organisms such as insects. As a result some beach creatures are nocturnal to avoid the heat of the day. Others spend most of the day in deep sand, where the temperature doesn't get too hot.
Tides
The tidal range determines the area of shore that is exposed to the air at any low tide. In the intertidal area, where the sand is subject to the ebb and flow of the tides, the sand remains moist. In the upper range of the intertidal area, the sand may dry out and blow inland. Spring tides reach high up on the beach. When they are combined with strong waves, they can cause wash-outs or breaches in the dunes.
Waves
The strongest waves on the beach are the ones that break on the surface (surf). They shift and sort the sand. Shifting sand hinders plants and animals from anchoring themselves. Storms with high waves can cause blowouts (breaches). They can destroy parts of dunes, making the beach more unstable. However, this is a natural process. Where the sea-levels rise, there is a landward migration of the beach/dune system.
Large, high-energy waves in the fall and winter have a completely different influence than the low energy waves of summer. Storms in late summer and fall hurricanes contribute to the longest waves. In the fall and the winter waves are even more damaging. In the fall they cause erosion of the beach and dunes. In the summer the waves actually help the beach by bringing in more sand.
Wind
The wind is a mechanism for the transfer of energy.
Dunes are formed by the interaction of sand and wind.
Miscou Island dune system
On the west coast of Miscou Island in northeastern New Brunswick a unique dune system has formed, with more than 30 parallel dunes. The area is called Grande Plaine by residents and is a perfect place to study dune systems. The dunes have different heights and are not regularly spaced. They were first noted in 1905 by W.F. Ganong, a New Brunswick naturalist, who wrote several articles on the phenomenon.
On the Grande Plaine, succession in the dune system can be observed very well. There is a definite transition from open grass dunes to dunes that are even covered with forest, interspersed with hollows that show a different plant composition. Rare plants have been reported here, and the area is well known to botanists throughout New Brunswick. The dunes also provide evidence that the dune systems have moved toward the ocean. Remnants of Walrus, a once abundant species in northeastern New Brunswick, have been found in an area far away from the shoreline. Proof can also be found for rising sea-levels. You can observe the characteristically steep cliffs where the beach has been cut and forced to retreat.
There are good examples of well-developed and successive dune ridges throughout the Maritime provinces. In Nova Scotia, Pomquet Beach in Antigonish County has one of the best examples of dune ridges in the province with up to seven. Bouctouche spit in New Brunswick also has good examples. In Prince Edward Island, one of the largest and best-developed dune systems can be found at the Greenwich sand dune system on the north shore.
Rising sea-level
Ice, storms, and wind are not the only forces eroding and changing beaches. The rising sea-level causes a more frequent overwash and a gradual landward migration of the entire beach system. Global warming has an accelerating effect on how much the sea-level rises. The ocean absorbs the increased heat in the atmosphere and warms up slightly, increasing the volume of water. Snowfields and glaciers melt, the amount of sea-water increases. A beach made up of loose sediment will move landward by 0.15 m per 1 mm rise in sea-level on, for example, the Northumberland shore.
