Generalities
These geological formations occur because the islands produce a refraction in the movement of the waves. Normally, this refraction of the waves is depositing the sand and the boulders in the area where they break. As the sea level rises, contributes to the sedimentation of all the materials deposited by the waves. These materials that have been pushed up are making a path like the ones we see in the case of Chesil Beach. This tombolo connects the Isle of Portland with Dorset reporting a boulder ridge along the coast.
Let's analyze the tombolo of the rock of Gibraltar. This rock is located in the extreme southwest of Europe on the Iberian Peninsula. It is nothing more than a limestone promontory with a height of 426 meters. This rock is well known for hosting around 250 macaques, the last primates in the wild in Europe. It also has a labyrinthine network of tunnels that, together with the macaques, make it a tourist attraction all year round. This rock is considered a natural reserve.
Tombolos are also called "tied islands" because they appear to have never completely separated from the coast. This formation can appear solitary or found in groups. When found in groups, the sand bars form an enclosure similar to a lagoon near the coast. These lagoons are temporary, as they likely fill with sediment over time.
How a tombolo is formed
Longshore drift occurs when waves push up sediment. This sediment can be composed of sand, silt, and clay. This sediment accumulates between the beach and the island, creating an accumulation zone that can be seen as if the island were tethered to the mainland. Longshore drift depends on wind direction. For it to form continuously, the wind must be in a prevailing direction. Otherwise, sediment cannot accumulate in the same direction.
Sometimes, If these formations occur due to coastal drift, it is not considered a true tombolo. A true tombolo is one formed by wave diffraction and wave fraction. Waves follow a dynamic governed by the strength and direction of the wind. These waves head toward the coast and slow down as they move through shallower waters. This slowing is due to the waves' friction with the ground. This frictional force decreases the speed at which the wave travels to the point where it breaks.
Well, when it reaches the islands that are close to the coast, Because the waves are moving at a slower rate than normal, they travel around the island instead of over it. As the water moves more slowly around the island, it picks up sediment along the way. The sediment is deposited and continues to accumulate until it creates the sand bar that connects the island to the beach. Obviously, this is a very long process. That is, this has to do with the scale of geological time.
The world's most famous symbols
Next, we are going to describe the main characteristics of the most famous symbols in the world. We started with the one in Chesil Beach. It is located in Dorset, southern England. It is characterized by being 115 meters high above sea level and have a beach that is 29 kilometers long and 200 meters wide. Such is the importance of this tomboy that it has been named a World Heritage Site by UNESCO.
Another famous tombolo is the Trafalgar tombolo. This formation juts into the sea, giving it the appearance of a tuna fish with fine sand. It creates a beautiful landscape with extensive beaches in a rocky area, offering spectacular panoramic views. The interest in this formation stems from the fact that it is the only example of a double tombolo in Andalusia. In this geological feature, we find that the sand has been carried by the tides, creating two tombolos that have joined the islet and the coast. This union has enclosed a small depression within it that floods when rainfall is higher than normal. However, This depression has its days numbered, since the materials will be buried and the depth will decrease.
As the sea receded, the wind created a dune system on the beaches south of the islet. Over time, erosion has contributed to the fossilization of these dunes. This entire dune system is now covered by plants such as junipers and mastic trees. It's also important to note that vegetation helps to bind the sand. For example, we find sea wallflower, sea lily, and sea marigold flowers that help bind the sand and form a colorful layer.
In the stabilized areas, we can find sea hornwort, artemisia, and sea sage. Meanwhile, in the floodplain, we find reeds that serve as a frequent perching site for bird species such as the gull, red-billed gull, and sandwich tern.
I hope that with this information you can learn more about what a tomboy is and how it is formed.