Starting from Robinson Crusoe

"Do you not see the Snow Sea on Horse Drive River, where the vast yellow sands stretch to the sky.

The wind roars in Luntai in September night, stones as large as buckets scatter across the land like chaos.

...

At midnight, the army marches while spears clash, the wind is sharp as knives, cutting the face.

The horse’s fur carries snow and steam of sweat, five-colored coins quickly freeze into ice, and in the tent, grass memorials, and inkstone water congeals..."

This poem by Cen Shen, a Tang dynasty frontier poet, fits perfectly in this desolate prehistoric world.

The cold wind is like a knife, and beast skins congeal with frost.

When the wind blows, sand and stones fly, accompanied by fallen pine needles and dead leaves, resembling the apocalypse.

In such an environment, even three strong adult men often feel short-handed or struggle to survive, Chen Zhou can’t imagine the kind of days other challengers are living.

...

The weather is becoming colder, and snowfalls are becoming more frequent. Every time they go out, they almost never see a clear sky.

Sweeping snow has become a task that needs repeating every few days.

After thoroughly investigating the cave’s situation, worried about unexpected difficulties, Chen Zhou immediately organized Paul and Bi Kai to start moving.

Fortunately, they don’t have any large items to transport, but constructing the cave requires some thought.

After transferring survival tools, animal pelts, crude wooden beds, fired clay bowls, purified salt grains, carefully selected berries and pine nuts to the cave, Chen Zhou tasked Bi Kai with further confirming the condition of hibernating animals nearby while he began renovating the cave.

...

The first to undergo renovation was the entrance pathway of the cave, which slopes downwards. According to the pre-expectation, Chen Zhou planned to install a wooden staircase.

However, before installing the stairs, he did something more important —

A stove.

Chen Zhou intended to build a chimney using yellow clay and stone along the sloped path.

The chimney’s internal section would connect to the stove, and the stove to the fire wall. Thus, by lighting a fire inside the cave, they could both keep warm and cook food, boil water, while the chimney greatly reduces the risk of carbon monoxide poisoning, truly serving multiple purposes.

The cave is generally well-sealed, extending about seven to eight meters deep into the mountain with extremely thick natural walls to block the wind. As long as the entrance is sealed properly, there’s basically no need to worry about heat loss.

In fact, when Chen Zhou initially explored the cave, he clearly felt it was much warmer inside than outside.

The especially noticeable phenomenon was that snow taken from outside quickly melted when brought inside, indicating the cave’s temperature was at least eight to nine degrees.

Under such conditions, just adding a stable heat source inside could quickly raise the internal temperature to around twenty degrees, which is suitable for human survival.

Of course, ideals are ideals, and reality is reality.

Although Chen Zhou had acquired many practical survival skills while training on the island, building a chimney by digging clay in the cold Northern Territory was still quite challenging for him.

...

The first difficulty he encountered was how to dig out the clay.

Usable soil was almost impossible to find on Mount Baihar, but not far from the foothills was a river, with quite a bit of usable soil on its banks.

In the warm summer, this soil absorbed enough moisture that you wouldn’t need to dig; stepping on it could sink a person in.

However, this is winter.

The mud, saturated with water, was as hard as ice, chopping it felt like hitting stone, even making one worry about breaking the blade of the axe.

Hard mud like this, digging by sheer force would be time-consuming and labor-intensive.

Chen Zhou had to gather enough firewood and then start a bonfire over the chosen soil, using the flame’s temperature to melt the mud. Once the surface softened, he would then dig up the mud and load it into animal skin baskets.

Fortunately, with Bi Kai’s arrival, he had plenty of Great Horned Deer at his disposal. These robust animals could carry back hundreds of pounds of firewood and take away over a hundred pounds of mud with just one round trip.

In this way, with the help of the Great Horned Deer, Chen Zhou spent only a day gathering enough mud to build the chimney and stove and returned to the cave.

On the return journey, the mud in the animal skin baskets had already frozen hard, and once back at the cave, it inevitably had to be thawed again.

Since the chimney was not yet constructed, Chen Zhou could only light a bonfire near the entrance, resulting in smoke billowing into the cave all night. None of the three slept, ultimately carrying torches to gather stones outside for half the night.

However, this lesson, despite the torment it caused, gave Chen Zhou a reminder —

It’s crucial to build the chimney long enough, at least extending entirely outside the cave. Otherwise, if the wind direction is wrong, the smoke will be blown right into the cave.

...

The high-quality stone selected overnight, along with already melted yellow clay, mixed with dry grass leaves and some water, formed a slurry.

Using thin wooden boards as trowels, Chen Zhou, from bottom upwards, first imitated the common Northern stove to set up the stove, then slowly built the chimney.

When the chimney reached near the cave entrance, Chen Zhou lit the stove to prevent the grass mud structure from being dampened and breaking.

Normally, the mud needs to naturally air dry for a period to disperse the moisture before the surface becomes solid.

But in such cold winter conditions, the moisture couldn’t disperse from the mud before freezing into ice.

For this reason, Chen Zhou could only burn strong fires to forcibly dry the flue.

This forced drying resulted in the mud surface cracking, causing several smoke leaks in the flue, and whenever a fire was lit, smoke shrouded the cave passage.

Chen Zhou’s only solution was to make repeated repairs.

With each repair, the chimney became increasingly bulky, resembling a giant earth-yellow python, straightly coiled in the passage.