Limestone is a sedimentary rock, formed approximately 350 million years ago on the bed of a tropical sea.  The horizontal layers of rock are called bedding planes.   Vertical cracks in the rock caused by huge earth movements are called joints.   Limestone is a permeable, pervious rock because it allows water to pass through it by travelling along the joints and bedding planes.

Scree slopes are made up of angular pieces of limestone which have fallen from limestone outcrops.  Freeze-thaw weathering breaks up the rock.   Water in the joints freezes and expands, this puts pressure on the surrounding rock.  With continued freezing and thawing the rock eventually breaks apart.   The resulting angular pieces form patches of scree.  The effect of gravity 'sorts' the rock fragments with smaller pieces at the top of the slope and bigger pieces further down.

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