Rocks which do not allow water to pass through them are

The rocks which do not allow water to pass through them are called impermeable rocks. These rocks have very tiny or no pores, cracks or spaces between the particles that make up the rock, which means that water cannot flow through them easily. This makes impermeable rocks useful for building things like dams or lining ponds to prevent water from leaking out. On the other hand, porous rocks have spaces between their particles, which allows water to flow through them more easily. So, if you want to store water, you would want to use impermeable rocks to prevent it from seeping into the ground.