Les Blanches Banques EarthCache
Hidden : 7/25/2017
Difficulty:
2.5 out of 5
Terrain:
2.5 out of 5

Size: Size: other (other)

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Geocache Description:



Les Blanches Banques
 Bassata Dunes  bass 2
bass cam  bass ripp

The sand dunes of Les Blanches Banques, a very interesting biotope complex in the western coastal area of Jersey, are among the most important in Europe and because of their ecological value they were designated a "Site of Special Interest" in 1996.
 
The dune plain system (the lower, seaward area) overlies Neoloithic peat, which suggests the dunes have formed over the last 2000 years. The dunes of the high plateau are thought to be considerably older. Marram grass (Ammophila arenaria) is the most common species at Les Blanches Banques. It enjoys the calcium-rich environts of sand dunes, and also helps to form them. Its tough spiky foliage acts as a barrier to wind blown sand causing millions of grains to accumulate around the base of the plants and the rhizomous root system helps bind the sand. This interaction is fundamental to dune development.

Flora

The diversity of plant life among the dunes explains the reason for Les Blanches Banques being designated a "Site of Special (Ecological) Interest". Over 400 species of plants have been identified here, 16 of which are recorded in the "British Red Data Book" - the national list of rare or endangered species.

Fauna

The dunes provide an ideal habitat for Jersey's Green Lizard (Lacerta bilineata). This large lizard prefers a habitat of thick vegetation for cover and the margins of sandy footpaths from which to bask. Rabbits are the largest of the mammals found on the dunes. They provide a natural management system by cropping the grasses and providing the right conditions for smaller plants that would otherwise be overwhelmed. The dunes are also rich in insect life, particularly butterflies and a variety of grasshoppers, including the rare Blue-winged Grasshopper. 

Coastal dunes

In physical geography, dunes are hills of loose sand built by wind or the flow of water. Dunes occur in different shapes and sizes, formed by interaction with the flow of air or water. Most kinds of dunes are longer on the windward side where the sand is pushed up the dune and have a shorter "slip face" in the lee of the wind. The valley or trough between dunes is called a slack. A dune field is an area covered by extensive sand dunes. Dunes occur, for example, in some deserts and along some coasts.

Some coastal areas have one or more sets of dunes running parallel to the shoreline directly inland from the beach. In most cases, the dunes are important in protecting the land against potential ravages by storm waves from the sea. Although the most widely distributed dunes are those associated with coastal regions, the largest complexes of dunes are found inland in dry regions.

Coastal dunes form where the beach is wide enough to allow for the accumulation of windblown sand, and where prevailing onshore winds tend to blow sand inland.
As a coastal dune forms, plant succession occurs. The conditions on an emryo dune are harsh, with salt spray from the sea carried on strong winds. The dune is well drained and often dry, and composed of calcium carbonate from seashells. Rotting seaweed, brought in by storm waves adds nutrients to allow pioneer species to colonize the dune. These pioneer species are marram grass, sea wort grass and other sea grasses. Their deep roots bind the sand together, and the dune grows into a foredune as more sand is blown over the grasses. The grasses add nitrogen to the soil, so other, less hardy plants can then colonize the dunes. Coniferous forests and heathland are common climax communities for coastal sand dune systems.

Young coastal dunes are called yellow dunes and dunes which have high humus content are called grey dunes. Leaching occurs on the dunes, washing humus into the slacks, and the slacks may be much more developed than the tops of the dunes. It is usually in the slacks that more rare species are developed. If the dune slacks soil is waterlogged, marsh plants can survive.

Thanks to State of Jersey Environment for permission to place this EarthCache. There is no need to leave the paths for fulfilling the tasks of this EarthCache, so please, always stay on the paths! 


Your task to log this EarthCache as found:

Answer the following questions in your own words and send me the answers via message to my profile:
1.) Walk to Waypoint 1 (header coordinates). What do you think, is the point where you stand within the area of the yellow dunes or within the area of the grey dunes?

2.) What do you think, are the dunes at this point still moving or are they fixed? Explain your decision with your own words!

3.) Walk along to Waypoint 2. Looking to the area eastern of this point, can you observe any differences between this area and the area you have seen around waypoint 1? Is the sand still moving at this point?

4.) Walk along to Waypoint 3. Take a closer look to the sand! Describe it - its colour, the size of the grains...

5.) Optional: If you like, you are warmly invited to add a picture of you / your GPS at the location to the log!
You can log immediately after you sent me the answers! There is no need to wait for a log permission! I'll contact you if there's something wrong.
Have fun and enjoy!

Sources:

Bagnold, R. (2012): The physics of Blown Sand and Desert Dunes.
information boards near the earthcache location
Pye, K. & Tsoar, H. (2009): Aeolian Sand and Sand Dunes.
wikipedia.org
www.geography-site.co.uk/pages/physical/coastal/dunes.html

All pictures were taken by the author.

The most exciting way to learn about the Earth and its processes is to get into the outdoors and experience it first-hand. Visiting an Earthcache is a great outdoor activity the whole family can enjoy. An Earthcache is a special place that people can visit to learn about a unique geoscience feature or aspect of our Earth. Earthcaches include a set of educational notes and the details about where to find the location (latitude and longitude). Visitors to Earthcaches can see how our planet has been shaped by geological processes, how we manage the resources and how scientists gather evidence to learn about the Earth. To find out more click HERE.

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