At the entrance to the cave, in the camp marching tent. Jiang Lele handed the codex found from the tomb to the dean Zheng Hongda, and then the four of them put their hands on their knees side by side, waiting for the dean to analyze the information that may not have been found in the codex.

After all, Zheng Hongda is the dean of the Hero Academy, and he knows far more things than ordinary people, and no one else can see anything in this codex, so Dean Zheng Hongda may not.

"En......" Zheng Hongda finished reading the codex, then closed his eyes and muttered for a moment, then slowly opened his eyes and said, "Great discovery." ”

Crowd: "!!"

Really?

What a big discovery?

Hong Xiaofang hurriedly asked, "Dean, what do you mean ......?"

"Let's not mention this codex, I'll give you a science about what the cave is all about. Zheng Hongda looked at Hong Xiaofang, and suddenly squeezed his eyes with a smile: "There is nothing in the books, this can be said to be top-secret information." You are the owner of this cave, and your grandfather Hong Jun is one of the superheroes of the original ability war, so I will tell you. ”

Wow!

As soon as he heard this, Hong Xiaofang's saliva came down in an instant!

Curious!

"Suck the ......" Hong Xiao swallowed his saliva violently and said, "Then you say, you say, I'll listen carefully." ”

Although the other people pretended not to care on the surface, their ears were pricked up!

The secrets of the cave are never heard from outside!

This is why they are students of Hero Academia, and others are not qualified to listen!

"Our cave to the outside world is just the entrance to the underground world and the surface world, right?" Zheng Hongda said with a smile: "There are many caves in the world, and everyone just knows that the things in the cave are very valuable, and development will be of great benefit, right?"

Hong Xiaofang nodded: "Yes, is there still a secret?"

"Of course," Zheng Hongda sighed softly and said slowly, "Actually, the cave is hierarchical. I'm not talking about how deep the cave is, but it's essentially layered. ”

Crowd: "!!"

That sounds weird.

What kind of layer?

Fortunately, Zheng Hongda didn't sell it, and said, "Do you know the structure of the earth?"

Hong Xiaofang nodded: "I know, the atmosphere, the crust, the mantle, and the core." ”

"Well, do you know how thick the earth's crust is and how thick the mantle is?" asked Zheng Hongda again.

Hong Xiaoyan thought for a while, and then shook his head: "I don't know." ”

This knowledge is everywhere on the Internet, but it is not so easy to record it in detail.

Zheng Hongda said: "The thickness of the earth's crust is about 30 kilometers, and the thickness of the mantle is about 2,800 kilometers. ”

Hong Xiaofang's eyes widened: "And then?"

"And then the next thing has a lot to do with that. Zheng Hongda said: "In the system of sealing gods, you know the saying that there are 36 heavens and 18 layers of hell?"

Hong Xiaofang: "!!"

"What do you mean......" Hong Xiao said in a daze, "This cave layer, what do you mean?"

"Yes," Zheng Hongda nodded very affirmatively and said, "I'll say it from the inside out." The mantle is actually divided into the upper mantle and the lower mantle. The eighteen layers of hell in our legend refer to the lower mantle. In the lower mantle, the environment is extremely harsh, that is, human beings, including underground people, are basically unable to survive in the lower mantle, and even if they can live, it is eternal suffering. And in the legal system of the underground people, those heinous demon clans are usually imprisoned in the lower mantle and suffer forever. ”

Hong Xiaofang: "......"

Oh grass, this one is awesome!

"Is it so ruthless?!" Hong Xiaofang was shocked: "The eighteenth layer of hell is actually real?

"Of course there is," Zheng Hongda said, "The drone has gone down, and that scene ...... Tsk, it's really hell on earth! The demon clan who is locked up there is simply worse than death. ”

Everyone: "......"

"And the thirty-six heavens are different," Zheng Hongda continued, "Among the thirty-six heavens, what we usually call the Three Realms refers to the first twenty-eight heavens inside, that is, the four parts of the south, east, west, and northwest above the eighteen heavens of hell, each part has seven layers, and this part is the middle mantle to the upper mantle. This part is inhabited by the vast majority of ordinary people underground, and in these twenty-eight heavens, the aura is relatively thin, but there are still a lot. Therefore, there are often some ordinary people in these twenty-eight floors who become immortals after cultivating, and they can also enter the four burning heavens in the southeast, northwest, and north to live and live. And the teachings that were inseparable from the ground at the beginning were within this range. ”

Hong Xiao's crazy listening was very enjoyable.

In the past, he only thought that the gods were just a myth and legend, but now he knows ......

Really awesome!

"These four Brahmas are the Supreme Changrong Heaven, the Jade Dragon Tengsheng Heaven, the Dragon Transformation Brahma Heaven, and the Ping Yu Jia Yitian. Zheng Hongda said: "The location of these four floors underground is almost 400 kilometers underground to 600 kilometers underground. ”

Hong Xiaofang: "......"

It turns out that the myth and legend of descending to the eighteenth layer of hell and going up to the thirty-six heavens means this......

"Behind, there is Sanqingtian, which has the most abundant aura," Zheng Hongda said: "Sanqingtian is at the junction of the upper mantle and the earth's crust, and the aura here is the most abundant and resourceful. Here, it is an area where the demon clan is extremely active. It's just that because of the suppression of the exposition and interception of the teachings, there have been no big waves. And those who really can't be indoctrinated will be captured and imprisoned in the lower mantle, that is, in the eighteen layers of hell. ”

Hong Xiaofang: "I have gained knowledge!"

"The three Qingtians are the Taiqing Realm Da Chitian, the Shangqing Realm Yu Yutian, and the Yuqing Realm Qingwei Heaven," Zheng Hongda said: "This part basically belongs to the juxtaposed area, of course, we also analyzed it from the documentary records of the underground people. After all, the boss who guards there is basically an SSS-level or even a higher SSSS level, so we don't dare to mess with it. ”

Hong Xiaomad nodded.

This is easier to understand, this part basically belongs to the existence of nuclear weapons, and it is indeed better not to provoke easily.

"Speaking of which, we have reached the thirty-sixth heaven at the top, the Great Luo Heaven. Zheng Hongda said with a smile: "Da Luotian is actually the level we are at now. This is actually the dividing line between the ground and the underground, and the aura is thin, and the Codex you have found, the place of exile mentioned in it, is here. In fact, when we talk about high-resource caves, that's just relative to us. For the underworld, this is a barren land, and no underworld wants to come, so it's called the Land of Exile!"