Aquifer Formation: Sandstone vs. Granite

Why is sandstone more likely than granite to form an aquifer?

Which of the following is the correct reason?

A) The particles in granite are spaced further apart than is sandstone. B) Sandstone forms where it rains more often. C) Sandstone is more porous than granite. D) Granite repels water away from its surface.

Answer:

Sandstone is more likely than granite to form an aquifer because the particles in granite are spaced further apart than sandstone. In order for an aquifer to form, rocks have to be spaced out enough and permeable for water to be able to pass through. A is the answer.

When it comes to the formation of aquifers, the porosity and permeability of the rock play a crucial role. In the case of sandstone and granite, sandstone is more likely to form an aquifer due to its higher porosity compared to granite.

Porosity refers to the percentage of the rock that is made up of pore spaces, while permeability is the ability of a rock to allow fluids to pass through it. Sandstone, with its porous nature, has more interconnected pore spaces that can hold and transmit water, making it an ideal candidate for aquifer formation. On the other hand, granite, a denser and less porous rock, is not as conducive to aquifer development.

So, the next time you come across an aquifer, remember that the type of rock involved, such as sandstone with its high porosity, plays a significant role in its formation!

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