31
votes
Accepted
How do oases form in the middle of the desert?
Oasis are places where aquifers are connected to the surface. The source of the water in the aquifer however can be hundreds of miles away in areas that do get significant rainfall.
The trick is ...
- 7,037
28
votes
Was Judea as desertified 2000 years ago as it is now?
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 ...
- 14.3k
20
votes
Why are many fossils found in deserts?
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 ...
- 24.7k
18
votes
Accepted
What is this weird looking structure in Ethiopian desert?
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 ...
- 14.3k
16
votes
Accepted
Where did the sand in the Sahara come from?
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 ...
- 7,037
15
votes
Why are many fossils found in deserts?
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 ...
- 7,037
14
votes
Accepted
Is Atacama Desert cloudy or cloudless most of the year?
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 ...
- 17.7k
14
votes
How do oases form in the middle of the desert?
There are two types of oases: natural and human made.
Natural oases form when springs, created when underground aquifers allow fresh water to pool or flow on the ground surface of deserts, creating a ...
- 25.1k
11
votes
Was Judea as desertified 2000 years ago as it is now?
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 ...
- 23.3k
11
votes
Accepted
Is this a former volcano in the Hamad Plateau, in the Syrian desert?
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 ...
- 558
10
votes
Accepted
Why are many fossils found in deserts?
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 ...
- 626
9
votes
Accepted
Identifying a desert landform
Star dunes, caused by the prevailing winds coming from multiple directions.
Take a look at these different dune types.
- 7,037
8
votes
Accepted
What percentage of Earth's surface is arid?
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 ...
- 17.7k
7
votes
Is Atacama Desert cloudy or cloudless most of the year?
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 ...
- 596
7
votes
Is there any place on Earth that is permanently a desert?
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 ...
- 2,813
6
votes
Was Judea as desertified 2000 years ago as it is now?
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 ...
- 3,376
5
votes
Hypothetically, would digging a big trench from the ocean and flooding desert areas be a bad solution to combatting sea level rise?
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 ...
- 3,458
5
votes
Accepted
When was the first not-icy desert formed?
Deserts have existed since at least the Permian period (299-251 million years ago) when the world's continents had combined into the Pangaea supercontinent. Stretching from pole to pole, this land ...
- 3,458
5
votes
Accepted
If we could green the Sahara, would it be able to sustain itself?
The biggest detriment to keeping deserts green is of course water. With rainfall in the desert limited, afforestation is a tricky and potentially dangerous thing to do. China tried this for decades ...
- 753
4
votes
Where did the sand in the Sahara come from?
Only 25% of the Sahara is sand and dunes. 70% of the Sahara is bare rock and stones.
Un-watermarked version avaliable on www.alamy.com
Silicon makes up 27 percent of rocks on average. The Sahara is ...
- 1,349
4
votes
In general, does the presence of vegetation increase/decrease gross water loss (evapotranspiration) compared to barren land (evaporation only)?
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 ...
- 126
4
votes
In general, does the presence of vegetation increase/decrease gross water loss (evapotranspiration) compared to barren land (evaporation only)?
In addition to what has been (correctly) written in the other answers, I would like to add a couple of figures that could help to understand the dynamics involved:
The first figure is borrowed from ...
- 1,268
4
votes
Why are many fossils found in deserts?
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 ...
- 41
4
votes
Accepted
What is this big Black Mass in Syria, as seen on google maps?
This is the Al-Safa Volcano in Syria. According to Wikipedia it last erupted in 1850 AD.
- 2,197
4
votes
How can the Simpson Desert be the largest sand dune desert in the world?
The linked Wikipedia article has been edited after the OP's question was posted. It now says:
The Simpson Desert is a large area of dry, red sandy plain and dunes in Northern Territory, South ...
- 6,904
4
votes
Accepted
Why is reverse osmosis desalination the dominant method used and not heat-based methods? Also why is brine being dumped back into the ocean?
Starting with question 2): you can use heat to evaporate the water but you need some sort of energy or thermal exchange to cool and condense it back to liquid. My understanding is that reverse osmosis ...
- 4,427
3
votes
Are there areas of desert sands which experience blizzards?
It really depends on what you consider "desert sands". For instance, Sand Mountain in Nevada https://en.wikipedia.org/wiki/Sand_Mountain_(Nevada) is an area of sand dunes in a desert, and ...
- 1,738
3
votes
What percentage of Earth's surface is arid?
ARID LANDS: CHALLENGES AND HOPES by EARTH SYSTEM: HISTORY AND NATURAL VARIABILITY – Vol. III - Arid Lands: Challenges and Hopes - Barakat H.N.
Hyperarid zones cover 7.5% of Earth's land surface, ...
- 31
3
votes
When was the first not-icy desert formed?
the first one would have been the entire planet soon after it formed (~4.4 billion years), the planet had to cool quite a bit before liquid water could exist. deserts basically predate all the other ...
- 7,037
3
votes
In general, does the presence of vegetation increase/decrease gross water loss (evapotranspiration) compared to barren land (evaporation only)?
In general, evapotranspiration from vegetated areas is greater than the bare soil evaporation. You are correct that vegetation will increase the boundary layer and thus reduce evaporation at the ...
- 4,427
Only top scored, non community-wiki answers of a minimum length are eligible