Skrivnost nastanka namibijskih sipin

Na mojih FotoPOTEPih se ne ukvarjamo le s fotografiranjem – vedno se trudimo tudi kaj novega naučiti. Tokrat razkrivam, kako nastajajo in se še danes širijo znamenite sipine v najstarejši puščavi na svetu Namib, ter zakaj imajo tisto značilno rdečkasto barvo, ki jih dela tako fotogenične. Razlago nam v videu poda Ben Braynard, lastnik lokalne agencije Sand Waves, s katerim že več let sodelujem pri organizaciji izletov v sipine pri Sandwich Harbourju (članek: Sandwich Harbour – kjer se puščava zlije z oceanom) – na izjemno območje, kjer se puščava dobesedno sreča z oceanom.

Video z razlago.

Izvor peska

Večina peska, ki sestavlja sipine ob atlantski obali Namibije, izvira iz reke Orange. Ta reka, ena najdaljših v Južni Afriki, izvira v goratih predelih Lesota in teče proti zahodu, kjer se izliva v Atlantski ocean na meji z Namibijo. Pravzaprav reka Orange predstavlja naravno mejo med Južno Afriko in južno Namibijo.

Med potjo reka erodira in zbira sedimente, predvsem iz starodavnih kamnin Kaapvaalskega kratona. Kaapvaalski kraton ni vidna pokrajinska enota, kot planota ali gorovje, temveč geološka enota v notranjosti kontinenta, ki se skriva pod površjem in ima izjemno staro, trdno in stabilno zgradbo. Ta kraton je bogat z železovo rudo, kar pomeni, da je pesek, ki ga Orange odnaša, pogosto poln železovih oksidov.

Ko reka doseže morje, naplavi velike količine peska v ocean ob južni obali Namibije.

Vloga Benguelskega toka in jugozahodnih vetrov

Tu vlogo prevzame tok Benguele – hladen, močan morski tok, ki prihaja iz smeri Antarktike in potuje vzdolž zahodne obale Afrike proti severu. Ta tok postopoma prenaša pesek proti severu, vse do območja okoli Walvis Baya in Sandwich Harbourja, kjer se pesek začne odlagati na peščeni obali.

Od tam pa ga naprej prenašajo stalni jugozahodni vetrovi, ki ta sediment dvigajo in pihajo v notranjost. Tako nastajajo različne oblike sipin – vzdolžne, prečne in zvezdaste, značilne za Namib, ki imajo več krakov in so pogosto zelo visoke in stabilne.

Železo kot sidro sipin

Pomembno vlogo pri stabilnosti in videzu sipin ima prav železo v pesku. Sčasoma se železovi minerali oksidirajo, kar daje pesku značilno rdečkasto barvo. A še pomembneje – železo pesku povečuje gostoto in težo, zaradi česar ga veter težje raznaša. To pomeni, da se sipine, čeprav se premikajo, ne razpršijo – ostajajo oblikovane in obstojne, kljub močnim vetrovom.

Zaključek

Oblikovanje sipin pri Sandwich Harbourju je rezultat več naravnih procesov:

• dovod peska iz reke Orange, ki tvori mejo z Namibijo,

• transport sedimentov s hladnim tokom Benguele iz smeri Antarktike,

• stalni jugozahodni vetrovi, ki pesek pihajo v notranjost,

• in vsebnost železa, ki pesek barva, a tudi stabilizira obliko sipin.

Sandwich Harbour je tako naravni čudež, kjer narava ne oblikuje le čudovitih vzorcev za objektiv, temveč nam ponuja vpogled v milijone let geoloških procesov. Za fotografa pa to pomeni edinstveno priložnost: ujeti svetlobo, linije in barve v pokrajini, priložnost, ki se nikoli ne ustavi.

Članek: Sandwich Harbour – kjer se puščava zlije z oceanom

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How the Dunes at Sandwich Harbour Form and Endure

On my PhotoTRIPS, photography is just one part of the experience – we always aim to learn something new along the way.

This time, we explore how the iconic dunes of the Namib Desert form, continue to grow, and what gives them their distinctive reddish hue that makes them so photogenic.

The explanation in the video comes from Ben Braynard, owner of the local agency Sand Waves, with whom I’ve been organizing tours into the dunes near Sandwich Harbour for many years – a truly exceptional place where the desert quite literally meets the ocean.

Explanation - How the Dunes at Sandwich Harbour Form and Endure

Origin of the Sand

Most of the sand that makes up the dunes along Namibia’s Atlantic coast originates from the Orange River.

This river, one of the longest in Southern Africa, rises in the mountainous regions of Lesotho and flows westward, where it enters the Atlantic Ocean near the border with Namibia.

In fact, the Orange River marks the natural border between South Africa and southern Namibia.

Along its course, the river erodes and gathers sediments, primarily from ancient rocks of the Kaapvaal Craton.

The Kaapvaal Craton is not a visible geographical feature like a plateau or mountain range – it’s a deep geological formation hidden beneath the surface, incredibly old, stable, and solid.

It is rich in iron ore, meaning the sand carried by the Orange River is often full of iron oxides.

When the river reaches the ocean, it deposits vast quantities of this sand into the sea along Namibia’s southern coast.

The Role of the Benguela Current and the Wind

Here, the Benguela Current comes into play – a cold and powerful ocean current flowing from Antarctica, moving northward along the west coast of Africa.

It gradually transports the sand north to the area around Walvis Bay and Sandwich Harbour, where it begins to accumulate along the sandy coastline.

From there, persistent southwesterly winds take over, lifting the sediment and carrying it inland.

This results in the formation of various dune types – longitudinal, transverse, and star-shaped dunes, typical of the Namib, many of which are large and remarkably stable.

Iron – The Anchor of the Dunes

Iron plays a crucial role in both the appearance and stability of the dunes.

Over time, iron minerals in the sand oxidize, giving the dunes their characteristic reddish color.

More importantly, the iron increases the sand’s density and weight, making it more resistant to wind erosion.

This means that although the dunes shift and move, they do not simply blow away – they remain well-shaped and persistent, even under strong winds.

Conclusion

The formation of the dunes at Sandwich Harbour is the result of several natural processes:

• the supply of sand from the Orange River, which forms the border with Namibia,

• the transport of sediments by the cold Benguela Current from Antarctica,

• constant southwesterly winds that carry the sand inland,

• and the presence of iron, which gives the dunes their color and anchors their shape.

Sandwich Harbour is a true natural wonder – a place where nature not only sculpts stunning landscapes for the camera but also offers a glimpse into millions of years of geological history.

For a photographer, it’s a unique opportunity: to capture light, lines, and colors in a landscape that never stands still.