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Chalk is a sedimentary rock made of calcium carbonate. It is porous and allows water to penetrate into the rock. Where the chalk (permeable) meets an impermeable rock (frequently clay) springs form and can be seen when rivers begin to flow at the surface. Chalk is eroded by solution.
Subsequently, one may also ask, is Chalk porous or permeable?
Chalk is weaker than granite and tends to form more gentle rolling hills and valleys. Chalk is porous and permeable, so there is very little surface water and valleys formed in earlier times are now largely 'dry'.
Herein, what rocks are permeable?
Permeable rocks include sandstone and fractured igneous and metamorphic rocks and karst limestone. Impermeable rocks include shales and unfractured igneous and metamorphic rocks.
sedimentary