Chapter 806: Starting from Continental Drift...
Five o'clock in the afternoon.
This was the time when the temperature was the highest in the day, and Bifang and the camel hid under a rock wall to cool off.
"The best time to travel is from 4 to 11 in the morning, and then from 4 to 7 in the afternoon. You can travel overnight, but as I said, that's when animals are most active, so it's more dangerous, and in the dark, it's easier for people to bear greater mental stress."
"And people always need to rest. We are not camels. We cannot go for days without food or water. The nights in the Sahara are very cold. In a cold environment, you should sleep as much as possible. The heat you lose due to excessive activity will not be recycled."
"Don't worry that you will fall into a long sleep. Unless you are exhausted, you will be awakened by the cold before you freeze to death."
Bifang took a sip of water, let his arms hang naturally on his knees, squinted his eyes and looked at the scorching sun outside the shadow, there were heat waves and desert everywhere.
If you go out traveling with a large group or a camel caravan, you will naturally enjoy the magnificent natural scenery, which will broaden your horizons and your body and mind. But if you are alone, your heart will probably be filled with despair, right?
Bifang screwed on the kettle and pointed to the vast desert in front of him: "Can you imagine that the Sahara, which is now full of sand dunes, was once a dense forest."
[Imagine, I thought]
[Give me some face. Fang Shen doesn't want to see your reaction like this.]
[Pasta should be mixed with No. 42 concrete]
[Although I couldn't believe it, I'm not stupid. When Lao Fang said this, I knew that no matter how outrageous it was, it was true (dog head)]
【Reason tells me to accept it】
The comments were always weird, but Bifang, who had long been accustomed to it, did not interrupt his narration.
"Hundreds of millions of tons of dust are carried away from the Sahara every year by the northeast trade winds, and much of it is deposited in the Atlantic Ocean."
"Through the study of ancient sediments, scientists have discovered that over the past hundreds of thousands of years, the Sahara's climate has been switching regularly between dry and wet, with a time period of more than 20,000 years."
"Ancient murals found in the Sahara Desert also confirm this phenomenon from another perspective. In these murals, there are many animals such as horses, buffaloes, elephants, giraffes, etc. We all know that these animals cannot survive in the desert, especially horses."
"From about 40,000 to 20,000 years ago, the Sahara region was still a humid climate period, when vegetation was lush, rivers were crisscrossed, lakes were numerous, and floods were frequent."
"By 20,000 to 10,000 years ago, the climate here became dry, plants became scarce, and rivers dried up and became dry valleys."
"After this dry period, the climate turned humid again. Around 3500 BC, rainfall was plentiful, vegetation flourished, lakes and rivers filled up, and the water area reached its maximum."
"But after that, strong winds returned to this land, and the lush forests turned into grasslands, becoming a paradise for cattle, sheep, antelopes, and giraffes. Animals such as hippos and buffaloes became extinct, and fishing no longer existed."
"After 2000 BC, the climate became increasingly dry, and grassland animals also withdrew from the stage. Rivers dried up, lakes became smaller, dried up or disappeared, and vegetation withered and degraded. The grassland completely turned into a desert, and many grassland animals were forced to withdraw from the historical stage of the Sahara."
"Until now, the Sahara has completely become the world's largest and most typical tropical dry area."
[Why did it become like this? Is it simply due to the weather, or something else? ]
Environmental damage?
[Not necessarily, the Sahara seems to have been like this a long time ago]
"It's not environmental damage, it's the climate. If we have to say the root cause, it's the shrinking of the Tethys Ocean."
【What what what】
[Another thing I haven’t heard of]
[Is there such an ocean on Earth? ]
“Yes.”
Bifang grabbed a handful of sand and slowly slid down.
"Due to the movement of the Earth's plates, the land on Earth has actually been moving slowly. 40 million years ago, the plate where Africa was located was not in the position we see now. There was a wide ocean to the north, which was the Tethys Ocean."
"With the nourishment of a large amount of moist air from the ocean, there was no Sahara Desert in northern Africa at that time, but a large oasis."
"However, starting 40 million years ago, the African plate began to move northwards. As time went on, it eventually collided with the European plate, which caused the closure of the Tethys Ocean. The northern part of the African plate was also lifted due to compression, and more land was exposed to the sea."
"The contraction of the Tethys Sea not only led to changes in the mean climate state of North Africa, but also strengthened the response of the African summer monsoon to orbital changes, which subsequently became a major factor controlling changes in the extent of the Sahara Desert."
[Something strange flew into the top of my head]
[I seem to have glimpsed the truth of the world]
[Oh no, my brain is about to grow out]
"If the contraction of the Tethys Ocean is the fundamental reason, then the precession of the Earth is the direct cause of the regular changes in the Sahara's climate."
"The so-called Earth precession means that the Earth's rotation axis will rotate around the Earth's revolution axis under the influence of the gravity of the sun and the moon. The trajectory of this rotation in space is a cone surface with a period of about 25,700 years."
"We know that the amount of solar energy received is highest where the sun is directly overhead, and as the sun's inclination increases, the amount of solar energy received decreases."
"The Earth's precession will change the tilt of sunlight on Earth during the same season, thus affecting the distribution of solar energy between seasons on Earth."
"That is to say, the precession of the Earth will cause the sunlight energy in the same area of the Earth to fluctuate regularly in the same season, from less to more, and then from more to less. For the area where the Sahara is located, this will directly affect the strength of the summer monsoon."
"In fact, it is the sea breeze and the land breeze. If the summer wind is not strong enough, the sea breeze will be weak, and there will not be enough moist air from the ocean to enter the land, and gradually, drought will occur."
“Perhaps thousands of years later, this place will turn into a moist forest again and become a paradise for animals.”
[Fuck, I never learned these things...]
[Be more confident, high school geography doesn’t teach this]
[If I were still a high school student, I would not be able to say a word about this topic even if I were a high school student.]
[That's not right. The sea shrank 40 million years ago, so why did it turn into a desert only 40,000 years ago?]
"Continental movement is a slow process, because contraction is only the beginning. It was not until the late Miocene Tortonian stage, about 7 million to 11 million years ago, that the sea shrunk almost completely, completely cutting off the source of water vapor."
"The reason why the cycle only started 40,000 years ago has to do with the meteorological history of the Earth. In fact, the summer monsoon or prevailing wind belts that you see every year were formed only in the past tens of thousands of years."
"Forty thousand years ago, the Earth was still in the Ice Age, which had lasted for millions of years. There was no summer monsoon at all."
The audience fell into dementia.
This starts from continental drift, continues to climate change, and then to the history of the Earth. If you have not done professional research, you may not understand it clearly.
"How does this guy know so much?"
In the Egyptian camel caravan, Mugalen is riding on a camel and looking at his mobile phone with a constipated look on his face.
Is this something people should know?
Bifang flipped through his backpack and counted the supplies.
There is still plenty of water resources, and there are a few desert gourds hanging on the camels for replenishment, so they can last at least five days, but the food is not enough, and there are only a few dried fish.
The previous food was basically the leftovers from the fish caught in the second half of crossing Point Nemo, and it was almost finished after these few days.
Looking up and around, the original Gobi Desert has completely turned into a vast desert.
Bifang found a piece of dried fish, put it into his mouth and chewed it, watching the sun gradually setting .
"We need to build a shelter, and until tomorrow, we need to go find some food."
