Bar Island [Every Thing You Have To Know]



Bar Island


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Bar Islands are a popular summer destination for tourists and locals alike. These islands are formed when a river or stream clogs up with sediment and sand and builds up a barrier across its mouth.

As the water flow slows down and the sediment builds, the river or stream forms islands. The process of forming an island is called accretion.

There are different types of bar islands, including sand bars, gravel bars, clay bars, and cobble bars. Cobble bars are the most common type and are formed from river stones that have been smoothed by the current.

Bar Island

How bar islands form

How bar islands form

Bar Islands form from conditions in the stream or river where two unequal currents (fast and slow) work together to crush sediment into a cohesive ridge.

Natural erosion of bedrock gradually chisels out this rock,creating meandering channels through which water must flow. As small pools accumulate from these erosional pathways—on its way down the channel—the fast current collects fine material into a concentrated point downstream known as a sand bar).

The slow current then rushes in to fill the fast channel, and as it does so it carries with it fine sediments from upstream (usually cobbles).

When this slow flow meets the rapid flood-waters of a lake or larger reservoir, these tumbling pieces of bedrock can be thrown up onto an island that was previously buried by sediment.

After some time the intense water pressure crushes flat the stone against other stones and debris on shore.

The various processes of river/lake erosion and deposition will slowly move rock to create sand bars or bar islands over many years, as well as re-writing the contours of alluvial plain.

The usual process is:

Most natural seeps form the kind of pools called clay cones. They are usually two or more tiers deep and thin out gradually so that in some places they are less than a foot high when seen from above ground level; however.

What makes Cobble bars the most common type of bar island?

What makes Cobble bars the most common type of bar island?

The Cobble bar is formed from the bottom of streams or rivers, where a diagonal channel passes along it’s length.

The reason for the name ‘cobbles’ in connection with these bars is due to their appearance as ou cob stones created when flat-lying rocks are pressed against each other by water flowing through them at high speeds—approximately 60 miles per hour (100km), depending on the river.

The constant motion and forces exerted on the rocks cause them to chip and crack into cobbles, which in turn bed down against each other as they move downstream. Cobble bars are typically at least 10 feet (3m) across and 50-60 yards long whilst definitely not large enough to build a house on.

The word is believed to come from an Old Norse word meaning rocky bottom or block of wood. Other possible derivations include OIr ‘klanda’, a block of wood; or from ‘koble’, an old Norse word for what is now the Norwegian dialect word “knull”.

Unlike the local names such as Bys and Strid, Cobble bars are found all over Europe, although they exist only in small numbers compared to other types. On any given journey it would be rare for someone not to come across at least a couple within their travels. The main reason that cobbles.

Which rivers and streams create cobble bars?

Which rivers and streams create cobble bars?

Foraged cobble bar island locations are found in the most diverse set of rivers and streams from Scotland, down to northern England. They form wherever there is a channel running along the site; usually within driven gravel at low water depth but more often below man-made river deposits such granite stair platforms for crossing or maintenance vehicles

In what was once considered to be a very poorly charted area – The Forth & Clyde Canal has many disused canalised sections containing some of the most interesting barbed point features.

The Clyde river from Glasgow to Busan, Japan was used for transhipment since 1936 and is a large and deep channel connecting several major bodies of water including Loch Long in Scotland, Lagan Water North Channel which leads into Belfast Loughs & Armagh Strangford estuary .

What are the different types of sandbars?

What are the different types of sandbars?

The most common sandbars tend to fall in the two category. Firstly, smaller around 1 foot (30cm) across and just over 2 feet (60 cm) deep; commonly found within some rivers and streams.

Secondly are larger cobble bars that typically measure 4–25 meters wide by 30 – 100 meters long. Commonly called ‘cobles’ these can be up to 10 meters deep  and are generally located close to the shore or in a channel between two large banks of gravel. These cobles can have steep sides and people readily underestimate their danger especially driving alongside them.

Cobble bars are also found at lakeside, where they form low-lying islands on either side of wide channels choked with water to about 4– 5 inches deep The leading theory for these is based upon streams turning into small rivers and then deteriorating over time due to lack of

Why are clay bars different than other types of sandbars?

Why are clay bars different than other types of sandbars

Clay bars are typically elongated linear features that form on the banks of streams and rivers. Clay bars appear as a series of parallel ribbons along the bank most commonly cut by water erosion, however they can also be quite steep slabs up to several meters deep – some even subdivided into many smaller fragments.

Unlike cobble banks though clay is much more stable which makes it safer for wading and walking since animals prefer sand over clay unless digging or digging their nests.  

It is believed that clay starts as a thin veneer of mud covers existing sand to form geologically cohesive layers across the riverbed on which subsequent erosion takes place, this creates elongated linear features in the beds whereas cobble are reformed by t whilst retaining fragments similar to cobblestone only smaller around 1 foot (30 cm) large & 2 feet (60cm) deep.  Why aren’t these.


The above explanations are only a brief highlights into the importance and distribution of alluvial deposits. Also, sedimentary geology is relatively new in South Africa compared to other African countries where educational syllabus exist integrated with geological knowledge base already.

As typically information extends more readily in European languages whilst Arabic can be somewhat harder to access & understand depending on translation quality while literature may not necessarily include detail rarely explained on international forums ( often abbreviated) due delays,


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