Aggregate 1: A surfacing or ballast for a roof system. Aggregate may be washed, rounded gravel, whole or crushed stone, crushed lava rock or limestone or marble chippings.

Aggregate 2:
May refer to several hard materials including crushed rock, sand, gravel, stone, and other inert materials.

Ballast: roofing shingle, usually 40-20mm

Chalk flint: large unknapped flints partly coated in chalk. See also field flints.

Cod’s heads: hand selected cobbles usually 2-3 “ Gravel aggregate resulting from the natural erosion of rock. In geology, gravel is loose rock between 2 millimeters in and 75 millimeters its largest dimension.

Knapped flint: flint split down the middle to reveal dark glossy centre

Field flint: see chalk flint

Kent potatoes: hand selected cobbles usually 3-4”

Paddle stones: flat, decorative stones

Paramoudra: very large chalk flint, naturally pierced by water action. Signature decorative stones.

Rainbow stones: large stone/small boulder circled in various brown, yellow and red tones. Decorative.

Sand generally refers to particles less than 2 mm in diameter. Sand is larger than silt and smaller than gravel