Why can a weak drop of water penetrate a hard rock?

Listen to some geological knowledge and understand the great philosophy of life! I believe everyone is familiar with the idiom "water drops wear away the stone". It was first mentioned in "Book of Han·Biography of Mei Cheng" by Ban Gu in the Eastern Han Dynasty, which describes a phenomenon in which water drops can wear away rocks.

I believe you will also find that there is often a row of neat pits on the stone steps under many eaves. Yes, this phenomenon is the most intuitive manifestation of "dripping water wears away the stone" in our daily life.

(Picture from Laozhou Popular Science Public Account)

So the question is, how do weak water drops penetrate rocks? In fact, there is a wealth of scientific knowledge involved.

(The picture of water drops under the 1000-frame lens is quoted from the Internet)

In geology, we call the phenomenon of water dripping through a rock erosion, which is a physical and chemical process that removes and dissolves the material on the surface of the rock and then transports it to other places. Let's take a look at how water drips through rocks!

Studies have shown that when water droplets with a diameter greater than 2 mm fall in the air, they will change into the shape of a steamed bread under the action of gravity, resistance and surface tension.

(Picture from Laozhou Popular Science Public Account)

When these steamed bun-shaped water droplets hit the rocks, tiny bubbles will form between the water droplets and the rocks. At the same time, the water droplets will transfer the kinetic energy they carry to the bubbles, increasing their pressure, and will gather high energy around the bubbles, turning them into high-pressure bubbles.

(Picture from CAE College of Technology)

(Picture from Laozhou Popular Science Public Account)

When these bubbles burst, they create powerful shock waves that cause damage to the rock surface. Although this damage is small, it cannot be ignored.

Another reason why water drops can wear away a stone is that carbon dioxide in the air dissolves in water to form carbonic acid. When these acidic water droplets fall on limestone and marble, they react chemically with the calcium carbonate in the rock to form calcium bicarbonate that is soluble in water. As the calcium bicarbonate is carried away by the water droplets, tiny pits are left on the rock surface.

Among them, the well-known caves and karst landforms were carved by erosion of aqueous solutions.

(Picture from the Internet)

(Picture from the Internet)

The story of water dripping through stone ends here. Although it sounds simple, the process is extremely long. What is commendable is that the water drop can finally penetrate the stone with its tenacious perseverance.

This story also tells us that only through the accumulation of quantity can there be a qualitative leap. We should make a little progress every day and keep going. I believe that one day, we can also achieve the final success through our own persistence and hard work like a drop of water!