A guide to the coastal ecology of New South Wales from the 1940s praises the many rock platforms found along the shorelines of eastern Australia:
Horizontal platforms provide every kind of niche beloved by the shore animals for, owing to cracks and hollows, they provide pools of all sorts and sizes, shallow and deep, together with overhanging ledges, stones, and overhanging rocks with beautifully sheltered holes and crannies beneath them. Even a rough weathered surface provides useful depressions which retain sea-water, or provide shade, or both. (Dakin et al 1948, 204)
The coastlines in question intersperse beaches and rock platforms. These platforms biogeochemically mix sediment, the remains of hard-shelled creatures, microbes and minerals, and the veins and dykes of igneous rock such as quartz intruding from beneath the crust. The rock platforms unfold complicated edges of varying shape and thickness. Actually, not just on rock platforms, but along edges of many different kinds – between shadow and sunlight, between air and soil, between hard and soft, hot and cold or moist and dry – lives diversify.
The coastal rock platforms are edge-thickening events. Along their many edges, gradients of nutrient, water, air, sunlight, and heat shift with tides, seasons, sea levels and climate. They create the possibility of many niches in the same places. Edges are sites of pluralization and, because of that, are sometimes densely populated. The liveliness of coastal rock platforms owes much to tides, to weathering and sea levels, to processes of weathering and the relative durability or solidity of rock to waves, sand and sun.