THE QUIVERING AND SWELLING OF THE EARTH
And you see the earth dead and barren. Then, when We send down water onto it, it quivers and swells and sprouts with luxuriant plants of every kind. (Qur'an, 22:5)
The Arabic word for "quivers" is "ihtazzat," meaning "to set in motion, come alive, quiver, move, stir; the movement and stretching of a plant." The word "rabat," translated as "swells," bears the meanings "to increase, grow in number, swell, grow, develop, rise (of a plant), provision, fill with air." These words describe in the most appropriate manner the changes that occur in the molecular structure of soil during rain.
The motion described in the verse is different from the movement of Earth's crust, such as when a portion of it moves to produce an earthquake, for it is only the soil particles that are moving. These particles are composed of layers, each of which is on top of the other. When water penetrates the layers, it causes the swelling of mud particles. The stages referred to in the verse can be scientifically explained as follows:
1. Quivering of the soil: The electrostatic charge on the particle surface that appears after the water falls on the soil in sufficient amount would cause its instability and quivering movements. This movement is stabilized only after this charge has been neutralized with an opposing one. The soil particle's moving and quivering is also due to its collision with water particles. Since the water particles move in no specific direction, the soil particles move as they are struck from all sides. Robert Brown, a Scottish botanist, discovered in 1827 that when raindrops fall on the soil, they cause a kind of shaking and vibration in the soil molecules. He described this movement of microscopic particles, which today is known as the "Brownian motion."