Two million years of rainy season

The Earth's crust not only provides us with solid ground to stand on but also preserves various traces of the Earth's past. By studying the strata formed in ancient times, we can learn from them what the Earth's natural environment was like in the distant past.

Since the 1980s, scientists have noticed the existence of a special layer of gray rock in the Triassic strata. Because the entire Triassic strata are mainly arid, but in this layer of gray rock, there are a lot of signs of heavy rainfall, such as silt deposits, peat, obvious signs of being washed by water rocks, etc.

In further studies, scientists found that this particular layer is widespread in the strata of the same period, and also found a large number of signs of heavy rainfall in the fossil plants and animals of the same period and the sedimentary rocks of the coast.

Radiocarbon dating results indicate that this period of intense rainfall began about 234 million years ago and ended about 232 million years ago, which in turn means that the Earth had a 2-million-year rainy season during which almost the entire planet was dominated by rainy days and since this period belongs to a Triassic period - the Since this period was part of the Triassic period - the Carnic period (about 237 to 227 million years ago) - it is known as the "Carnic flood event".

The question then becomes, will such a long rainy season occur in the future? To answer this question, we need to look at the causes of the Carnian flood event.

The Earth's lithosphere is not a monolith but is divided into several plates, which are constantly in motion as the Earth's internal currents surge. Although the speed of plate movement is unusually slow, averaging only a few centimeters per year, if the period is long enough, plate movement can significantly change the distribution of land and sea on the Earth's surface.

During the Triassic, the land surface of the Earth was almost united as a whole, which was called the "Pangaea". It is because of this that the entire Triassic stratigraphy is mainly arid.

After the Carnian period, the "Pangaea" had begun to break up, which caused more and more volcanic movements on the earth, so more and more carbon dioxide was released from the earth's interior, and they continued to accumulate in the earth's atmosphere, triggering a stronger and stronger greenhouse effect, and the temperature of the earth's surface also became higher and higher, which in turn The temperature of the earth's surface is increasing, which leads to the evaporation of large amounts of seawater from the oceans.

A large amount of water vapor rises with the hot air, and when it meets the cold air at a high altitude, it condenses again into water droplets, which then spill to the ground under the action of the earth's gravity, forming rainfall.

As the volcanic movement continues, rainfall becomes more and more frequent, and at the same time, the air currents in the earth's atmosphere become stronger and stronger, thus causing the rainfall area on the earth's surface to become larger and larger, and when it reaches a certain level, even the deepest part of the "Pangaea" is enveloped by the moist air from the ocean, thus forming Rainfall on a global scale.

Although large amounts of rainfall can lower the temperature of the earth's surface and dilute some of the carbon dioxides in the atmosphere, the constant volcanic movement will cancel out the cooling and carbon dioxide dilution effect of the rainfall.

In this way, a delicate balance was created, and widespread rainfall on Earth continued until about 232 million years ago when this violent volcanic movement subsided and the "Carnian flood event" ended.

The reason for the 2 million-year-long rainy season on Earth is that the larger-scale volcanism continued to release large amounts of carbon dioxide into the atmosphere.

In other words, if there is another long and large-scale volcanic movement on the Earth in the future, the long rainy season will appear again. Although we do not know enough about the interior of the Earth, we can be sure that in the foreseeable future, the interior of the Earth is still dark and the plate movement has not stopped, so we cannot exclude this possibility.

It is worth mentioning that scientists have speculated, based on the current trend of the Earth's plate movement, that in about 250 million years, the Earth's land will be connected again as a whole.