Sand dunes

In physical geography, a dune is a mount of sand built by eolian (wind-related) processes. Bare dunes are subject to changing location and size based on their interaction with the wind. The "valley" or furrow between dunes is called a slack.

Some coastal areas have one or more sets of dunes running parallel to the shoreline straight inland from the beach. In most such cases the dunes are important in caring the land against potential ravages by storm waves from the sea. Although the most broadly distributed dunes are those associated with coastal regions, the largest complexes of dunes are found inland in dry regions and associated with ancient lake or sea beds.Dunes also form below the action of water flow (Alluvial processes), on sand or gravel beds of rivers, estuaries and the sea-bed.

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Sunglasses

Sunglasses may be made with either prescription or non-prescription (i.e. plano) lenses that are darkened to offer protection against bright visible light. Good quality sunglasses should also protect against ultraviolet light. Due to changes in the atmosphere, ultraviolet levels are much elevated than in the past and ultraviolet protection for eyes and skin is even more important. It is possible to have lenses that seem very dark and yet offer little ultraviolet protection. Sunglasses fluctuate greatly and many offer more style than protection.

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Railway

A railroad or railway is a guided means of land transport, designed to be used by trains, for transporting both passengers and goods. It consists of two parallel rails, usually made of steel, and wooden or concrete sleepers or ties that hold the rails accurately at the proper distance from each other. Rail transport is one of the most energy well-organized means of mechanised land transport known. The rails offer very smooth and hard surfaces on which the wheels of the train may roll with a minimum of friction. This is added comfortable and saves energy. Trains also have a tiny frontal area in relation to the load they are carrying, which cuts down on air resistance and thus energy usage. In all, under the right situation, a train needs 50-70% less energy to transport a given tonnage of freight (or given number of passengers), than by road.

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