Because Bowen’s shores are so rocky, beaches are limited to pockets at the heads of bays. But islanders value them as places to access and enjoy the natural, wild beauty of Atl’ka7tsem/Howe Sound. It is here that we are most likely to encounter the water’s teeming wildlife, enjoy the salty aroma of ocean waters, and savour the refreshing coolness of a swim on a hot summer’s day.
Kwilákm has two significant beaches: Sandy Beach and Pebbly Beach, and one small pocket beach: Mothers’ Beach (see map).
How Beaches are Formed
The beaches of Kwilákm are associated with small streams (Terminal Creek for Sandy and Mother’s Beaches and a small unnamed stream for Pebbly Beach). For thousands of years, these streams have have eroded sand and gravel deposited by Ice Age glaciers across Bowen Island and carried them to the shore where they are deposited. Wave action holds the coarse sediment close to shore and spreads it laterally, while fine muds drift away to settle off shore in deeper water.
Because waves and tides tend to move sand and gravel out to sea, our beaches require a constant supply of new sand and gravel. Sandy Beach and Mother’s Beach receive new sand and gravel eroded from the banks of Terminal Creek. Pebbly Beach receives new materials from a small un-named stream and from gravels eroded by rain and waves along the shore.
A local geologist has observed that is likely that the construction of the Causeway in the 1920s changed the dynamics of beach building in Kwilákm.
Before the Causeway was built, Terminal Creek flowed directly into the Bay, regularly adding new sand and gravel to Sandy and Mother’s Beaches. Now Terminal Creek dumps its load of sand and gravel at the head of the Lagoon, filling the Lagoon rather than the Bay. As a result, little new sand is added to Sandy and Mother’s Beaches. Eventually both may be eroded by wave action and disappear.
Life on the Beach
Many who visit beaches for recreation conclude that beaches are lifeless deserts. The sand and gravels are hot and dry in summer, cold and damp in winter, and tide and wave action will wash any small plant or creature out to sea. But any small child who has spent time exploring a beach will tell you otherwise. In fact, Kwilákm’s beaches are teeming with life forms, each specially adapted to the beach zone it inhabits.
The beaches of Kwilákm can be divided into four zones. Each has different conditions that affect life within it. Each is a great place to explore for signs of life when visiting a beach.
Located above highest storm level. Vegetation casts cool shade on other zones of the beach, providing relief from direct sun.
Located above high tide level except during storms. Conditions are hot and dry in summer and cold and damp in winter.
This zone often includes a wrack line, composed of decaying seaweeds and marine creatures washed ashore by wave action
Dry Beach Creatures
Consists of logs thrown onshore by winter storms, located at high edge of the beach
High Tide Line
This is the upper level of tides that come ashore twice daily. High tide levels vary over the month depending on the moon’s gravitational pull.
Low Tide Line
This is the lower level of tides that retreat from shore twice daily. Low tide levels vary over the month depending on the moon’s gravitational pull.
This is a zone of seaweed and floating debris washed ashore by waves at high tide. This area of nutritious decaying seaweed attracts a whole community of tiny specialized creatures adapted to make use of this abundant food source.
This is the area below the low tide zone. It is exposed only during very low tides that occur only a few times each year. Creatures living here have few adaptations to being exposed to the air.
These are depressions in the beach where water from the retreating tide remains. It is home for many kinds of hardy marine creatures that can handle high water temperatures and low oxygen levels until high tide brings in fresh seawater.
Located between the high tide and low tide lines. Each day at low tide, the sea floor and creatures living here are exposed to the hot drying sun in summer and cold air in winter. Most intertidal beach creatures burrow into the sand to avoid these harsh conditions
Rotate your device to view diagram.
Beaches Are Ever-changing
Bowen’s beaches appear to be stable, never-changing entities of mud, sand, gravel, and pebbles. However, a keen observer can see that they are in a state of constant change.
The materials that make up beaches are constantly rearranged by winds, tides, and waves. Changes in beaches can be most clearly seen seasonally.
Summer is when Bowen’s beaches increase in size. Winds are less strong, producing smaller widely-spaced waves that move sand and gravel from deeper water landwards and deposit it on the beach front.
Winter is a time of storms. Waves are larger and taller, and tend to move the sand accumulated on a beach seaward, leaving behind cobbles and boulders. Winter beaches are smaller. Some even disappear completely.