Geography of Scotland example at Aberdeen. Much of the Scottish coastline consists of a machair formation, a dune pasture land formed as sea levels subsided. The east coast has several significant estuaries and other nature reserves including the Ythan Estuary and Fowlsheugh, both of which have been designated as Important Bird Areas. Firths of Scotland include the Solway Firth, Firth of Clyde, and Firth of Lorne on the west coast, and the Cromarty Firth, Moray Firth, Firth of Tay, and Firth of Forth on the east coast. The Pentland Firth is not an inlet, but the strait that separates the Orkney Isles from
Firth which are not termed such – Likewise, in the Northern Isles, the words "firth" and "sound" are often used arbitrarily or interchangeably. Bluemull Sound for example, is very similar to some of the firths in the Shetland Islands. Firth Firth is a word in the Scots and English languages used to denote various coastal waters in Scotland and even a strait. In the Northern Isles, it more usually refers to a smaller inlet. It is linguistically cognate to "fjord" (both from Proto-Germanic *"ferþuz") which has a more constrained sense in English. Bodies of water named "firths" tend to be more