Why do deserts form?

 

Last week we spoke of sandy beaches along the vast seas… And today we take a look at a different kind of oceans, the endless expanse of dunes we know as desert.

Much like on the beach, in the desert sand due to erosion, inheriting the colour of the rocks and soil and varying in consistency according to the extent of weathering. Unlike our favourite summer destination, however, deserts are the last thing we want to spend our vacation in unless it’s to see the pyramids or the spring blooms.

Photo by Winfried Bruenken

Photo by Javier Rubilar

Deserts can be cold or hot and equally unfriendly to the majority of living beings, but how do they form and conquer so much land?

A variety of conditions and reasons lead to the formation of deserts but by far the most important are distance from the ocean and the presence of natural barriers such as mountains. The further we get from the seas, the dryer the air becomes as moisture is absorbed by the land and plants along the way leading to little or no rainfall in the inner areas. Mountains, like the Andes or the Himalayas, are also excellent shields against moisture, trapping clouds to one side and leaving the other dry.

Desertification also depends on the winds, dryer, hotter winds in the equatorial zones can slowly erode the land into finer and finer sand. These winds prevent the formation of clouds and the dryer the area becomes, the fewer the plants keeping the soil together. The more sand is formed due to erosion, the stronger the wind erosion becomes as sand is carried on, grinding down hills and suffocating plant life.

Or at least that’s the simple version. Deserts may be hot or cold, covered in sand, pebbled stone or even ice, they can have little to no vegetation or a cover of low grasses, what they all have in common is the aridity. Whether no rain falls, or the land and air are unable to preserve moisture, the lack of surface water leads to scarcity of plants and large empty planes of sand or ice dunes.

References and additional reads:

National Geographic Encyclopedia: Desert

Bright Hub: Learn How Deserts Came Into Existence

St. Mary College Media: How are deserts made?

Geology Class: The Geology of Deserts

Wikipedia: Desert

Vikings

Today we depart for the frozen wastelands in the far north. To a treacherous landscape dotted with forests, beasts and danger that gives birth to the toughest of marauders and warriors: Vikings. A historical drama about, well Vikings.

The plot is relatively simple, it’s about Vikings, their society, laws, customs and beliefs. We follow Ragnar Lothbrok, played by Travis Fimmel who, tired of constant raids to the east, embarks on a trip west in search for richer lands and loot.

However historically accurate the show is, it’s engaging enough, though it can be too dramatic at times which can slow down the action quite a bit.

As expected and demanded from such series the props, make up and fight scenes are good, everything well made and choreographed. The acting is decent too, and the series is shot well and on location in Ireland.

Overall I’d give it a watch, especially if you like hardcore historic dramas about people struggling to make a living in a harsh world riddled with battles, political, social or actual.

Without further ado, Vikings episode one: Rites of Passage.

We open in the Eastern Baltic Sea, sometime early AD. Or so the caption tell us before panning to a tree being struck by a lightning and the face of a bloody viking, Ragnar. It’s the aftermath of a battle and the winners are culling the fields for any survivors. One of the victors looks over the land littered with corpses and perhaps it’s his fatigue playing tricks on him but he sees the figure of death strolling among the bodies accompanied by crows. He blinks and a vision of valkyries descend for the souls of the warriors.

Unspecified time later, in Scandinavia, two women are fishing in a shallow body of water. It’s Ragnar’s family, his wife and daughter fetching dinner while he trains his son with the sword. A perfect picture of normalcy.

The next day the father and his son depart for the annual gathering, and no sooner is he gone that two vile looking men invade his house. His wife offers them drinks or food if they’re in need, but they desire other things. However, viking women are no pushovers and Lagertha, played by Katheryn Winnick, shows them the right way to use a heated hearth poker.

Every summer the men are sent at sea to raid for resources in foreign lands. Usually, they’re sent east, but the people there are as poor as them so our protagonist intends to argue for sailing west. His confidence comes from a sundial/compass he received from a wanderer but the lord isn’t easily swayed by the offer, instead taking offence in his meddling.

We also see the viking court of law in action and the preciousness and political struggles for farmland, the lord rules, the people rule, and the criminals are punished.

After the refusal, Ragnar finds himself at a loss so he consults the oracle of the gods. But like any other prophet, he grants him a cryptic answer. With the oracle being no help, Ragnar goes to talk to Floki, played by Gustaf Skarsgård, a boat builder and a seer of sorts. But he does not seek advice, he has asked instead for a boat to sail without the need for his lord’s assistance.

While the stars are aligning, Ragnar returns home to discus the crew gathering with his brother in arms. Who for some unfathomable reason decides to mess with his wife. Not a smart idea considering she’s an ex shieldmaiden. So why would Ragnar’s self proclaimed brother try to seduce his wife?

Nevertheless, she promptly puts him in his place, her words as sharp as her sword.

Meanwhile as Ragnar is tying up the boats, he sees death again. He takes it as a sign that they are doing the right thing.

Soon the boat is ready, but Floki isn’t too confident in his craft. It was too fine an idea for him to pull off, he claims, but Ragnar believes it won’t sink.

The episode ends with a nice cliffhanger of the lord pouting upon hearing about the boat.

Overall not bad, anyone who likes character drama would find it engaging enough. Good acting, decent story and okay fighting whenever it happens. The episode was slow, but engaging, give the show a watch if you like historical reimaginings.

What determines the colour of sand?

If there was one place we’d rather be on a hot summer day, other than a well air conditioned room, it’s the beach. Palm trees, clear skies, pristine waters, and golden sands as far as the eye can see.

Or maybe white sands, orange, or black, or red, or even green. Beaches come in many shades. So what determines their colour, and the colour of sand in general?

The short answer is the geology of the region.

Sand is composed of fine particles formed when rocks and minerals are weathered down and eroded. In Hawaii or Iceland we find black sands formed by lava rocks like basalt. In other places we see red beaches because of the high iron content in the soil. Beyond rocks and soils, common ingredients are shells, corals or minerals like quartz that give the sand a pink or even pristine white hue.

Usually sand is a mixture of different types of minerals and rocks that make it brown or tan in colour but when we have a dominant or single source of formation, we may get  quite vivid colours.

References and related reads:

Wikipedia: Sand

Coastal Care: Beach Basics

Rock Cycle lab: Analyzing the Origin of Different Sands

Tourism on the Edge: World’s Most Beautiful Colorful Sand Beaches

Pictures: Spectacular Sand Beaches in a Rainbow of 10 Incredible Colors