the building absolute height remains constant. The Crowne Plaza high-rise hotel in Burlingame, California was also designed to sit over bay muds, as was the Westin Hotel in Millbrae, California and Trinity Church in Boston's Copley Square. Indeed, Boston's entire Back Bay district is named for the tidal bay that it now covers. Logan International Airport and the San Francisco International Airport are also constructed over bay mud. Mudflats When the mud layer is exposed at the tidal fringe, mudflats result affording a unique ecotone that affords numerous shorebird species a safe feeding and resting habitat. Because the muds function much like quicksand, heavier mammalian predators not only cannot gain traction for pursuit, but would actually become trapped in the sinking muds. The muds are also an important substrate for primary marsh productivity including eelgrass, cordgrass and pickleweed. Furthermore, they are home to a large variety of molluscs and estuarine arthropods. Richardson Bay, for example, exposes one third of its areal extent as mudflat at low tide, which hosts a productive eelgrass expanse and also a large shorebird community. Mammals such as the Harbor seal may use mudflats to haul out of estuary waters; however, larger mammals such as humpback whales may become accidentally stranded at low tides. Note that normally humpback whales do not frequent estuaries containing mudflats, but at least one errant whale, publicized by the media as Humphrey the humpback whale, became stuck on a mudflat in San Francisco Bay at Sierra Point in Brisbane, California. Worldwide occurrences Bay muds occur in bays and estuaries throughout the temperate regions of the world. In North America, prominent instances are: (a) the Stellwagen Bank formed 16,000 to 9000 BCE by glaciation of Cape Cod Bay in Massachusetts, (b) Florida Bay, (c) in California Morro Bay and San Francisco Bay and (d) Knik & Turnagain Arms in Anchorage, Alaska. In the United Kingdom large bay mud occurrences are found at Morecambe Bay, Bridgwater Bay and Bristol Bay. Straddling Denmark, the Netherlands and Germany is the Wadden Sea, a major formation underlain by bay muds. In Asia the Chongming Dongtan Nature Reserve in Shanghai, China is an example of a large scale bay mud formation. The Atlantic coast of Africa holds the Banc d'Arguin, a World Heritage nature preserve in the country of Mauritania. Banc d'Arguin is a vast area underlain by bay mud. Regulatory issues and actions When building on