In oceanography, geomorphology, and earth sciences, a shoal is a naturally submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material, and rises from the bed of a body of water near to the surface. Often it refers to those submerged ridges, banks, or bars that rise near enough to the surface of a body of water as to constitute a danger to navigation. Shoals are also known as sandbanks, sandbars, or gravel bars. Two or more shoals that are either separated by shared troughs or interconnected by past or present sedimentary and hydrographic processes are referred to as a shoal complex.
The term shoal is also used in a number of ways that can be either similar or quite different from how it is used in the geologic, geomorphic, and oceanographic literature. Sometimes, this terms refers to either any relatively shallow place in a stream, lake, sea, or other body of water; a rocky area on the seafloor within an area mapped for navigation purposes; a growth of vegetation on the bottom of a deep lake that occurs at any depth; and as a verb for the process of proceeding from a greater to a lesser depth of water.
Shoals are characteristically long and narrow (linear) ridges. They can develop where a stream, river, or ocean current promotes deposition of V and granular material, resulting in localized shallowing (shoaling) of the water. Marine shoals also develop either by the in place drowning of barrier islands as the result of episodic sea level rise or by the erosion and submergence of inactive delta lobes.
Shoals can appear as a coastal landform in the sea, where they are classified as a type of ocean bank, or as fluvial landforms in rivers, streams, and lakes.
A shoal–sandbar may seasonally separate a smaller body of water from the sea, such as:
The term bar can apply to landform features spanning a considerable range in size, from a length of a few metres in a small stream to marine depositions stretching for hundreds of kilometers along a coastline, often called barrier islands.
Sandbars, also known as a trough bars, form where the waves are breaking, because the breaking waves set up a shoreward current with a compensating counter-current along the bottom. Sometimes this occurs seaward of a trough (marine landform).
Sand carried by the offshore moving bottom current is deposited where the current reaches the wave break. Other longshore bars may lie further offshore, representing the break point of even larger waves, or the break point at low tide.
Harbour and river bars
A harbor or river bar is a sedimentary deposit formed at a harbor entrance or river mouth by: the deposition of freshwater sediment, or the action of waves on the seafloor or up—current beaches.
Where beaches are suitably mobile, or the river's suspended or bed loads are large enough, deposition can build up a sandbar that completely blocks a river mouth and damming the river. It can be a seasonally natural process of aquatic ecology, causing the formation of estuaries and wetlands in the lower course of the river. This situation will persist until the bar is eroded by the sea, or the dammed river develops sufficient head to break through the bar.
The formation of harbor bars can prevent access for boats and shipping, can be the result of:
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construction up-coast or at the harbor — e.g.: breakwaters, dune habitat destruction.
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upriver development — e.g.: dams and reservoirs, riparian zone destruction, river bank alterations, river adjacent agricultural land practices, water diversions.
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watershed erosion from habitat alterations — e.g.: deforestation, wildfires, grading for development.
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artificially created/deepened harbors that require periodic dredging maintenance.
When the QEW was built between Built 1931 – October 14, 1956 They had a few obstacles to go around. 15, 16, 18 and 20 mile creek Instead of Building a bridge over the whole creek opening they dammed most of it and left a small stream for all that water to flow through a tiny stream (see image below 15 18 and 20 mile creek in photo gallery). This process caused The creek to backflood and also allowed the creation of the sandbar and shoal( a sandbar already existed but now the sandbar Is higher and does not allow water to flow over) This applies to all of the creeks in this area.
The former entrance of 16 mile creek
Logging requirements:
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Explain In your own words how this sandbar formed.
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Explain in your own words how the highway impacted the sandbar.
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Is this type of shoal a Harbour/river bar or a Shoal/sandbar
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Look for where you think the Water most recently spilled over the sand bar( hint: It might not always be where the map shows!) tell me where that is
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Go to stage 2( this is where the creek formerly entered lake Ontario) What Is the major feature that Indicates the creek was formerly here. Is there any remaining evidence of a sandbar?
Good luck!!!
Congrats to Carni, WC65, KL52 and NFJK for FTF
