Sands have a story to tell

Commonly perceived as a beige, grey, white or black pleasantly soft playground for summer pastime, sand is much more. Looked at more closely on this varying mixture of mineral grains or tiny rock fragments, sand of all environments, seashores, lakesides, river banks and deserts alike, reveals a microcosm of geomanifestations reflecting various geological processes, and disclosing vast variety of structures, textures, colours and compositions. Originating from the disintegration of solid rock by weathering and erosion, on transport by fluviatile (water), glacial (ice) and aeolian (wind) processes the rock fragments are grind, separated, rounded and sorted and finally deposited in environments of decreasing strength of flow. As the ultimate destination of fluvial transport seas, lakes and alluvial plains accumulate sediment over time. Slipstreams at obstacles like hills or vegetation act likewise for aeolian processes thereby forming dunes and nabkhas.

However, all those sand accumulations are highly dynamic formations. The action of waves and wind continuously shifts and reworks the sand deposits, further separating and sorting, in the surf zone of littoral accumulations also grinding and rounding the terrigenous material and mixing it with biogenetic material originating in the body of water.

Common in both, arid continental as well as littoral environments but also occurring in windswept subglacial landscapes and in or along mountain ranges, the wind crimps the surface of sand accumulations forming ripple structures and heaps up the sand into regular aggregations known as dunes. On shores, the wave action and tide currents shape remarkable swash and backwash pattern, combined with natural flotation processes that lead to gravity separation of distinctively coloured mineral grains of different density, leaving behind colourful geometric pattern – until the next wave washes it away, forming new pattern.

However, all this artwork of nature can be observed at unspoiled river banks and beaches only, and, in times when enormous amounts of plastic pollute the oceans, may be mingled with or buried under layers of seaborne trash. On the other hand, mechanical beach cleansing, likewise beach nourishment, bulldozing or costal engineering, or even worse, beach mining for construction aggregate or heavy minerals recovery from placer deposits impede such artwork of wave action. Aeolian sand usually is too small-grained for concrete aggregate thus desert dunes are rarely mined. Still, except for very remote places, the fragile ecosystem of dune fields is endangered by strange and embarrassing pastime like “dune bashing”, unless protected by strict nature conservancy.

Click on the collage below to explore the picture stories and hidden treasure of sands.
However, just in case these pictures awake your enthusiasm for sands, be aware that removal of sand souvenirs is prohibited in protected areas and in some countries in general, thus may be subject to severe punishment. Better just take photographs.

Gerold Diepolder
Bavarian Environment Agency (LfU) – Geological Survey

Nina Rman
Geological Survey of Slovenia (GeoZS)

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