The Earth Story

Waw an Namus — A Saharan volcano From these images captured by the Operational Land Imager (OLI) on Landsat 8, the dormant volcano Waw an Namus looks like a drop of ink on a dusty piece of parchment. Located in Saharan region of southwestern Libya, the jet-black patch is made up of volcanic ash that was produced during the volcano’s last eruption. Although we don’t know the eruption's exact date, we know that it likely erupted some time during the past few thousand years, since the volcanic ash hasn’t yet been weathered and eroded away by wind or water. At the center of volcano lies a 4-km wide caldera — a depression that forms when a volcano with a shallow magma chamber collapses after a volcanic eruption.

Fossil Water in Africa

Is water a renewable or nonrenewable resource? Like many questions in science, the answer is “it depends”. Surface water, in ideal conditions, is replenished through rainfall and the hydrologic cycle (although like we’ve seen in recent droughts—such as the one in California—this not always the case). Groundwater can be replenished this way too, however, some aquifers contain fossil water—very old water that is definitely a finite resource.

Although it's a bit of a misnomer since it isn't quite a fossil, he term “fossil water” refers to groundwater that is no longer being replenished, originally got there by processes that are no longer active, and may have been untapped for thousands of years.  Most commonly, fossil water was deposited in wetter climates that no longer exist. Although it is a bit of a misnomer since it’s not a fossil, the name works as comparable to nonrenewable fossil fuels as fossil water resources are also nonrenewable—since the water is no long being replenished, when it’s gone, it’s gone.

The world’s largest fossil water aquifer is, ironically, sitting below the world’s largest desert. The Nubian Sandstone Aquifer System lies underneath the Sahara, specifically Egypt, Libya, Sudan, and Chad. Studies show that portions of this water may be as old as a million years, although on average the water is between 20,000-50,000 years old.

Four thirsty desert countries all grappling after the same water could potentially cause political conflict, but these countries have done fairly well at sharing their resource. A collaboration to research and regulate the aquifer was established in the 90’s and remains one of only four official agreements in the world regarding international (ground) waters.

-CM

Photo credit (an oasis in Libya): Sfivathttp://bit.ly/1HQOlIj

For a map of the Nubian Sandstone Aquifer System:http://bit.ly/1yVRKjZ

For more information: http://bit.ly/1y4CA0s

http://bit.ly/1Fh1e0C

http://bit.ly/1FBMUxc

To read more about another fossil water aquifer, the Ogallala aquifer: http://on.fb.me/1NTLNe9

Original caption:

An Oasis in the Desert.

In south-western Peru, in amongst the desert landscape, you can find the village of Haucachina. Development took place around a lagoon located in the area and serves a modest population of around a hundred permanent residents.

For drinking water, the inhabitants installed private, groundwater wells. Unfortunately, this water extraction caused the level of water in the oasis to drop dramatically. As a result, water has to be pumped in from the city of Ica, 8 kilometres away, to preserve this area of natural beauty.

Oases form when underground rivers or aquifers break the surface forming a body of water. However, prior to this knowledge, some interesting folklore was often attributed to these formations. In this case, local legend has it that the lagoon was created when a young hunter disturbed a bathing princess. The princess fled, leaving the pool of water behind her!

-Jean

Image by: Ingo Mehling

I’m thirsty.

A crescent oasis in the desert Lying near Dunhuang, China, the Crescent Lake (named YeuyaQuan, 月牙泉 in the Qing dynasty) was, for more than a thousand years, the last stop off for westward-bound traders before facing the rigours of the Gobi Desert. In recent decades the lake had begun to shrink in size, threatened by population growth and increased demands on it from farmers, for irrigation. Thankfully, the local government stepped in to save it, refilling it to past levels. ~SATR http://www.geopoem.com/2013/10/crescent-lake-dunhuang-china.html

Careful there…

I’ve never seen the Deadvlei salt/clay pan, that appears in this video, put into such contrast with the migrating sand dunes surrounding it. Amazing shots in that portion. This tour of some of the Namib desert also features majestic shots of sand dunes and ripples, a lot of wildlife including sidewinder snakes, an Arch, a visit to the Fish River Canyon, and an oasis with birds. Worth your time.

The Oasis of West Africa

The inland Niger River delta bursts into a lush oasis during the rainy season from July to October each year. Located on near the southern edges of the Sahara desert in Mali, the delta stands in stark contrast to the arid, windswept terrain surrounding it. Fed by the Niger and Bani Rivers, the inland delta grows to roughly 20,000 sq. km (7,700 sq. mi) at its apex and will shrink down to about 3,900 km^2 (1,500 sq. mi) during the drier months of the year. This outburst of plant growth and freshwater is the lifeblood of the entire region. The inland delta supports much of the economic activity for the country of Mali through fishing and agriculture and provides habitat for a variety of animal species.

For an even better perspective on just how unique this region is in comparison to its surroundings, see a larger version of the image used here (http://go.nasa.gov/1pBYRzq)

JRA

Image Credit: NASA http://go.nasa.gov/1SlH2hL

Sources: http://go.nasa.gov/1SlH2hL http://www.worldwildlife.org/ecoregions/at0903

Apparently on the right sand dune, “Sandboarding” is a thing. How about that. These are the Huacachina Dunes, in the Ica desert of Peru.  

Waw an Namus — A Saharan volcano

From these images captured by the Operational Land Imager (OLI) on Landsat 8, the dormant volcano Waw an Namus looks like a drop of ink on a dusty piece of parchment. Located in Saharan region of southwestern Libya, the jet-black patch is made up of volcanic ash that was produced during the volcano’s last eruption. Although we don’t know the eruption's exact date, we know that it likely erupted some time during the past few thousand years, since the volcanic ash hasn’t yet been weathered and eroded away by wind or water. At the center of volcano lies a 4-km wide caldera — a depression that forms when a volcano with a shallow magma chamber collapses after a volcanic eruption.

On the more magnified image, you can see several small lakes surrounding the volcano, which contributes to Waw an Namus being an important watering hole for caravans travelling across the Libyan region of the Sahara. These lakes, however, are infested with mosquitoes, which inspired the name “Waw an Namus” meaning “Oasis of Mosquitoes”.

-DC

Photo credits: http://1.usa.gov/1ClQgkv

More reading: http://bit.ly/1H3sDCZ http://bit.ly/1da3wSF http://on.doi.gov/1bCR2ME

Our previous write-up on Waw an Namus: http://on.fb.me/1FvTuSz

Ténéré Desert

Lifeless sand dunes where veiled ‘Blue Men’ trade in salt lie at the very heart of the Sahara Desert.

Land so devoid of life that it has been called the ‘desert within the desert’ lies just about as far from the sea as is possible in the Sahara. In the Ténéré Desert of land-locked Niger, rolling oceans of sand dunes, some as high as 800ft (244m), flow towards the horizon and lead to still more dunes in a seemingly endless progression. But like the Sahara as a whole, there is more to the Ténéré than just sand.

In an area the size of California, there are also gravel-covered plateaus blasted by desert wind, and fantastic rock formations linkened by one traveller to goblins, ogres and demons. On the eastern edge of the Ténéré, the oasis village of Bilma is the starting point for the camel caravans of the Tuareg who trek for 560km (350miles) across the desert carrying salt to trade in the market centre of Agadez. Bilma has given its name to the Grand Erg of Bilma—a vast expanse of sand extending eastwards for 1200km (750miles) from Niger into Chad. The Erg’s southern half consists of seif dunes—enormous parallel sand ridges—as much as 160km (100miles) long and 1km wide. The troughs between the dunes are known as gassis, and are used as routes by the caravan traders.

The nomadic Tuareg who roam this hostile environment are known as the ‘Blue Men’, from the covering of their faces—a costume that may have evolved as a protection against a day spent on camel back in the searing Sahara sun and wind—the dye of the cloth which swathes their heads and faces rubs off on their skin, hence their nickname.

~ JM

Image Credit: Camel Caravan by George Steinmetz for National Geographic. Sourced from http://bit.ly/1LQDKzm on 30/5/15

More Info: Sahara Salt Caravan: http://bit.ly/1AFpdFu Niger - Across the Tenere with Tuareg Camel Caravan: http://bit.ly/1cr3TI9 Ténéré: http://bit.ly/1eIOJzQ Air and Ténéré Natural Reserves: http://bit.ly/IESFRw