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28

There has always been a strong north-south rainfall gradient from approximately the Golan Heights (high rainfall), through Judaea and southwards into the arid Sinai desert. We know that this gradient once had a higher rainfall because there are abundant rainfall harvesting and groundwater collection structures, built by the Nabatean civilization about 400 BC ...


19

Bones don't last very long in jungles. Or in forests. Or almost anywhere. Fossils are the consequence of one highly unlikely fluke after another. Darwin himself commented on this. It takes just-right circumstances to have the bones of a recently deceased animal not be eaten by scavengers or turned into rot by bacteria. It takes yet another set of just-right ...


16

Zoom in for the clues. The lines are not radiating out from the village, but from the cattle kraals. These kraals are irregular enclosures built of acacia thorn, agave and other thorny bushes. The cattle are kept in these kraals at night to protect them from hyenas and packs of wild dogs. The cattle themselves are likely African longhorn or various local ...


15

The 'bluish' areas are exposed gypsum and gravel across which the sand dunes are moving. The colour is likely an artifact of the 'natural' colour palette used when processing the SPOT image. To understand just how arbitrary and variable the results of that processing can be, consider the following image captured at a fairly high zoom level in one of your '...


15

Because you find fossils by looking at exposed bedrock, deserts by their nature often have huge expanses of exposed bedrock. The lack of plants is also a big benefit, plant roots tend to destroy fossils Fossils are everywhere you have sedimentary rock* deserts are actually rather poor at forming fossils compared to many other environments. They are FOUND ...


14

There are two types of dust storms. The first, a dust storm or "sandstorm", is associated with a synoptic scale feature (like a low pressure system). Strong winds along air mass boundaries (i.e. cold front) create clouds of dust as sand, dust, or other particulates become suspended by turbulent eddies near the surface and aloft. The second, the infamous "...


14

The Atatacma desert comprise a very large area of more than 100,000 square kilometers, that host very different climates. The main factors driving the climatic variability are the distance to the Pacific ocean and elevation. This latter factor is very strong, as the Atacama desert covers a formidable elevation range, from sea level to almost 7,000 m, at the ...


12

The sand IS the original dirt, or at least what's left of it. Sand is one of the major constituents of soil. Soils are roughly half minerals by volume and those minerals are silt, sand, and clay. In fact sand is often the largest single constituent of most common soils. Silt and clay are smaller and lighter, and can be moved by wind much easier when dry, ...


11

This is an interesting question & I've been waiting to see what answers, if any, would be written. One affect of creating such a lake would be a localized increase in humidity in the vicinity of the new lake, but nothing that would significantly increase rainfall. By bringing in salty sea water there could be a risk of contaminating existing ...


10

Based on past events supported by archeological finds climate change will affect it. Here is a short quote from an about.com referencing National Geographic "... recent excavations at the site of Gobero in Niger indicate. Gobero is a cemetery site, including at least 200 human burials located on top of a ridge or set of ridges, sand dunes with a ...


10

tldr: It was also dry back then, which is why the people living there were rebels and not the rich elite. I'd like to add a few points to Gordon's answer. First of all, Masada is on the western edge of the Judea Desert, and therefore it is dry now and was extremely dry back then. The water supply to it was based on abundant water reservoirs that were built ...


10

I would contend that the fact that the location is a desert has little to nothing to do in most cases to the existence of fossils at the location. Most of the fossils in the location, at least the ones that make most headlines like major dinosaur deposits, were left there millions of years ago. The fact that a location today is a desert has no indication ...


10

My Rand-McNally Atlas shows the signature for lava fields in that area. The elevations in Google Maps indicate concentric contour lines with only small differences in elevation, rising from 600m at the outer perimeter to 700m in its center. This a shallow cone-shaped formation. Best I can tell from Wikipedia (compare the picture there), this feature is: ...


9

Star dunes, caused by the prevailing winds coming from multiple directions. Take a look at these different dune types.


8

These features are created by the wind.You will note that the upper left portion has a small dark spot. This is known as Waw al-Namus, or the "Oasis of Mosquitoes." It has a path of material in the same curved manner as the surrounding features you mention. From the link provided below: However, Waw al-Namus and its plume are not the only "wind records" ...


8

Nevada is 286,367 km² in area. With a conservative average evaporation of 2500 mm/yr in your desert, a lake of that size would evaporate 22686 m3/s. That is a flow larger than the average river discharge of the Nile. As you can see in the plot, the best price for pumping water to an elevation of only 50 m above the sea level is 0.131 \$/3.78 m3, so to pump ...


8

It will depend on the exact definition of "arid" and the period of time. But using the widely used and accepted Köppen climate classification, "arid" would correspond to the four climates in climatic group B: "Dry (desert and semi-arid) climates". Using the most up-to-date present climate data (2006) provided by the WORLD MAPS OF KÖPPEN-GEIGER CLIMATE ...


7

Sandstorms occur in dry areas, particularly deserts. The sand particles are fairly uniform in size. As the dry sand moves due to the wind it begins a leaping process known as saltation. Quoting the Wikipedia article: the initial saltation of sand particles induces a static electric field by friction The sand particles become polarized and as the ...


7

Sahara greening is generally driven by the strength of the North African Monsoon, which follows the earth's orbital cycles pretty neatly. (Piquet's answer covers this). http://en.wikipedia.org/wiki/North_African_climate_cycles The answer to how much man made climate change will affect the North African Monsoon extent isn't clear. Man made climate ...


7

I see three issues to be considered and will address them in what I think is reverse order of importance: 3) Cost: you have considered this with solar power and by trying to use mud to reduce infiltration through the lake bed. Fair enough, for now let's assume the scheme could be cost effective. 2) Negative impacts on the environment. You will get ...


7

Atacama desert is cloudless most part of the year. Except for the litoral, where a fog from the sea goes inland. This phenomena is called camanchaca. Telescopes for astronomy are located in high places, not only to avoid this weather, but also because at high altitudes the atmosphere is thinner and the weather is dry, both good for observation. Besides, ...


6

Minimum volumes of mobile sand can be estimated for each region of the Sahara, such as the 26 meter average thickness of the Erg Oriental of Algeria. Sand migration model conclusions regarding such volumes of sand are that the current Saharan dune distribution and morphology took at least 1.35 million years to evolve, possibly much longer if there were long ...


6

Gordon Stanger covers the climate aspects well in his answer, but I thought I'd chime in with an answer to the "was it as much a desert as it is now?" While I'm not aware of any archaeological evidence for the agriculture in the land surrounding Masada at the time of the siege, there are several factors that may have, at that time, made the area less '...


6

UserLTK, above, has mentioned the Dry Valleys of Antarctica and the Atacama desert as two notable examples of "permanent" deserts. It's likely that these two locations have been deserts for at lease several millions of years despite changes in global weather patterns from multiple glacial events. The Atacama is well shielded by a very old mountain range to ...


5

For an example of how bad agricultural practices can cause soil loss and end up with dust and sand, see the conditions that preceded the dust bowl in the USA. Certain crops are bad for soil and if not rotated will eventually deplete the soil of nutrients leading to no crops. With nothing holding the soil in place (roots) it will erode. The Sahara has other ...


5

Yes, it would be a bad solution. Aside from the construction and maintenance cost, the impact to the populations affected, and the impact on the environment around the destination, the benefits would be minimal, as roughly calculated in the answer to Volume of Land Below Sea Level So to reduce the sea level by 1m the total area of these depressions ...


4

I think it is best to introduce some definitions. Often in such studies, two types of evapotranspiration (or evaporation, but I will stick to evapotranspiration during this answer for convenience) are defined: actual and potential evapotranspiration: Source: presentation called Water resources and their management in Pakistan by Jannat Iftikhar As you have ...


4

Because there is nothing in the way. Looking for stuff in a jungle is difficult because of limitation of vision and difficulty of moving equipment and supplies. Looking for fossils in downtown Duckburg is difficult because local ordnance prohibits digging big holes. Deserts, while hostile, are easier to traverse and cater. Many fossils in the UK are ...


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