The term hard landscape is used by practitioners of landscape architecture and garden design to describe the construction materials which are used to improve a landscape by design. The corresponding term soft landscape materials is used to describe plant materials. A wide range of hard landscape materials can be used, such as brick, gravel, rock or stone, concrete, timber, bitumen, glass, metals, etc. 'Hard landscape' can also describe outdoor furniture and other landscape products.
A pebble is a clast of rock with a particle size of 4 to 64 millimetres based on the Krumbein phi scale of sedimentology. Pebbles are generally considered to be larger than granules (2 to 4 millimetres diameter) and smaller than cobbles (64 to 256 millimetres diameter). A rock made predominantly of pebbles is termed a conglomerate. Pebble tools are among the earliest known man-made artifacts, dating from the Palaeolithic period of human history.
A beach composed chiefly of surface pebbles is commonly termed a shingle beach. This type of beach has armoring characteristics with respect to wave erosion, as well as ecological niches which can provide habitat for animals and plants.
Pebbles come in various colors and textures, and can have streaks of quartz and different colored sedimentary rock. Pebbles are mostly smooth but, dependent on how frequently they come in contact with the sea, they can have marks of contact with other rocks or other pebbles. Pebbles left above the high water mark may have growths of organisms such as lichen on them, signifying the lack of contact with seawater.