Bra allows the wearer to use the tighter hooks as the bra stretches during its lifetime. Bras may be designed to enhance a woman's breast size, or to create cleavage, or for other aesthetic, fashion or more practical considerations. Nursing bras are designed to aid breast-feeding. Compression bras, such as sports bras, push against and minimize breast movement, whereas encapsulation bras have cups for support. Breast support may be built into some swimsuits, camisoles and dresses. Bras come in a variety of styles, including backless, balconette, convertible, shelf, full cup, demi-cup, minimizing, padded, plunge, posture, push-up, racerback, sheer, strapless, T-shirt, underwire,
Continental shelf frequent earthquakes that move sediment to the deep sea. The shelf usually ends at a point of increasing slope (called the "shelf break"). The sea floor below the break is the "continental slope". Below the slope is the "continental rise", which finally merges into the deep ocean floor, the abyssal plain. The continental shelf and the slope are part of the continental margin. The shelf area is commonly subdivided into the "inner continental shelf", "mid continental shelf", and "outer continental shelf", each with their specific geomorphology and marine biology. The character of the shelf changes dramatically at the shelf break,