- The Sahara, meaning “desert” in Arabic, stretches across North Africa. The Sahara is the world’s largest non-polar desert, over 9,000,000 km² (3,500,000 mi (5,632,704 kilometers)²), which is about the same size as the United States.
- Although the Sahara is famous for its sand-swept dunes, the majority of the surface comprises Hamadan or rocky plateaus. The Sahara’s fabled dune fields cover only about 15% of the entire desert’s surface and lie primarily in the north-central region. In the dune-laden sections of Algeria and Libya, the sand thickness varies because dunes can pile up to a height of several hundred meters, but then change as the sand moves.
The desert expanse is dominated by rocky, barren stretches with arid hills and valleys.
- What many do not realize is that the Sahara was once a fertile area that supported thriving human communities. A study of cores revealed that North Africa’s ancient climate underwent swift desertification and a climate shift, transforming the region from a humid, subtropical landscape to desert within a matter of years. This occurred around 4200 B.C. It returned to the same desert conditions that dominated the area 13,000 years earlier.
- When the climate began to change, the Sahara region became parched, and the vegetation died away. With nothing to hold the soil in place, wind action could remove all the fine sediment, leaving only sand, rocks, and bedrock.
- The transition from the mid-Holocene climate to the present one was triggered by changes in the Earth’s orbit and the tilt of its axis. Some 9,000 years ago, Earth’s tilt was 24.14 degrees, as compared with the current 23.45 degrees, and perihelion (the point in the Earth’s orbit that is closest to the Sun) occurred at the end of July, as compared with early January now. The Northern Hemisphere received more summer sunlight, which amplified the African and Indian summer monsoons.
- The changes in Earth’s orbit occurred gradually, whereas the evolution of North Africa’s climate and vegetation was abrupt. German researcher Clausen and his colleagues believe that various feedback mechanisms within Earth’s climate system amplified and modified the effects triggered by the orbital changes. By modeling the impact of climate, oceans, and vegetation both separately and in various combinations, the researchers concluded that oceans played only a minor role in the Sahara’s desertification. Wade El Titan (Whale Valley), in Egypt, solo, contains the fossilized remains of an extinct sub-order of whales. Evidently, the valley was part of a shallow marine basin 40–50 million years ago. The desertification helped both preserve and reveal a tremendous hoard of fossils.
- Most journeys involved taking a heading across the sands using landmarks, smoke, and stars for guidance. Some were marked with barrels every km, but they disappeared under the sand as it moved around, continually changing the landscape. There was no GPS at the time, nor were there cell phones. Radios that we could use only worked for very short distances. Getting lost was a real possibility and usually a death sentence. They would stop looking after 3 days, assuming you had succumbed to the heat.
- On a single trip of 4 hours, you could encounter many typical surfaces. This desert is typically comprised of hard, brittle sedimentary rocks. There is also firm sand and soft sand. You would need to constantly alter the pressure in your tires to match the surface you were on. Higher pressures to protect your sidewalls from the Savannah rocks, and lower pressures to widen the base of your tires to allow you to move in soft sand. The depth of the sand went from zero to a few feet in many parts of the desert. There are other sections like the Great Sand Seas where dunes towered over you 100–200 ft. They are difficult to climb and typically require you to find a path around them. The depth of the sand there could also be 100 -200ft (ca. -61 m), so just a lot of sand.
- In my journeys, I found many diverse items, like a petrified forest with stone logs everywhere. Desert glass, large stretches of a melted sand layer from God knows what. Shark’s teeth and other undersea fossils. Bullets from when the Italians invaded at the turn of the century. Wrecked fighter jets and old encampments. Equipment from WW2 and beautiful rocks, with ponds and even fish sometimes. Old Roman ruins and beautiful beaches. Really an amazing place. The desert was a shallow sea a very long time ago, and a green and productive Savannah before it became the desert that it is now.
TOP 10 DESERTS BY SIZE.
AN ARCA ARCTIC, Sahara, Australia, GLOB I, SAUDI ARABIA, Argentina, GREAT BASIN.
DESERTS ARE 20% OF THE GLOBAL LAND MASS Surface
- R sand seas (ergs) such as the Grand Erg Oriental and Grand Erg Occidental in Algeria, the Rub’ alkali Kali (Empty Quarter), and parts of the Libyan Desert can have dune fields with sand bodies commonly 20–150 m thick; locally they exceed 200–300 m where long-term transport and accumulation occurred.
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- Originally Answered: How deep is the sand of the Sahara Desert? What is below it? Is it a gradual transition, or is it like pure sand dumped directly on some previous flat surface?
- Only about 20% of the Sahara is sand, which is typical of deserts everywhere. The typical desert surface is stony and somewhat lacking in dedicated oil, since it is Kali and tends to blow away. Nonetheless, the Sahara has some major ergs scattered across its expanse.
- The sand is relatively shallow west of its shallowest point in between the dune crests;, it probably averages less than 200 meters. Sand is the result of erosion in a very dry environment, in which wind moves the smaller particles into an area of accumulation. In the American West, which has many much smaller and younger dune fields, the process is a lot more obvious. Beneath it is a brief transition zone of surface crust that was exposed at one time, transitioning quickly to bedrock. Sand is really no different from other erosional depositions in other environments, such as soils in wetter environments. Sediment basins can accumulate much thicker amounts than typically occur in a desert environment.
- The bottom layer of sand is forming at Segatimetimsouthwest, e —, southwest, a.IME rock as it slowly leathers. The red rock country of time, Thea. The US is an example of the nitrification of dunes in an erg sea over the eons into sandstone. There must have been repeated eras over millions of years in that area to create so much beautiful sandstone, which is mostly Cretaceous and Jurassic in age.
- If you research it, the Nile used to flow east to west and emptied into the Atlantic and not the Mediterranean.
- Satellite photos show the Nile WAS ONCE FERTILE and flowed West.
- So that would translate to the Sahara was once a river or part of a small seafloor.
