DUNES, mounds or hills and ridges of sand heaped by wind. They are numerous in (1) deserts, particularly in low-lying areas; (2) on sandy coasts with onshore winds; and (3) near rivers of which the volume varies, leaving sandy beds exposed during the dry season. The areg of the Sahara and Arabian deserts are char acterized by vast expanses of dunes, as are the koums of the deserts of Persia and Turkistan and the plateaux of Gobi and other Mongolian deserts. Few such desert dunes are found in America or Australia, but the sand hill region of western Nebraska affords a good illustration. The coasts of Brittany, Cornwall, the Landes of France, the shores of the Baltic in Europe ; the whole eastern coast of North America from Cape Cod southward, and at places along the Pacific coast; and numerous leeward coasts of Africa, Australia and Asia serve as examples of oceanic coastal dunes. Lacustrine dunes are admirably developed on the east shore of Lake Michigan, the south shores of Lake Superior and Lake Erie, the shores of former Lakes Lahontan and Bonneville in the Great basin of North America, and on the east shores of the Caspian and Aral seas in western Asia. Examples of river bank dunes are found in almost every land, as for instance along the east banks of the Mississippi, Missouri and Rio Grande rivers in the United States.
Dunes migrate constantly unless the sand of which they are composed is prevented from blowing by grass or other vegetation. The rate at which dunes move varies, depending upon the velocity of the wind and the height of the dunes, small dunes migrating the faster. In Denmark the rate is from 3 to 20 ft. a year; in France, on the Bay of Biscay, the sands have advanced at a rate estimated from 15 to 105 ft. a year, burying in their progress forests, farms, vineyards, churches and whole villages, some of which may in course of time be exhumed as the dunes migrate onward. On the south side of Lake Michigan forests which were buried by sand dunes have been uncovered as the dunes moved on. Hundreds, perhaps thousands of square miles of towns and cities in central Asia are buried under dunes. Moving dunes constantly encroach upon the Suez canal. Nor are dunes merely a contemporary geologic feature. Sand dune deposits are recog nizable by the character of their bedding in sandstone rocks of many geologic periods, indicating that aeolian action has been prevalent throughout geologic history. Fossil dunes are widely distributed. See DOWNS. (W. E. E.) DUNFERMLINE, JAMES ABERCROMBY,1sT BARON (1776-1858), speaker of the House of Commons, third son of Gen. Sir Ralph Abercromby, was born on Nov. 7, 1776. He was called to the bar at Lincoln's Inn in 18oI. He sat in parliament for Midhurst (1807) and Calne (1812) in the `'Whig interest. In 1827 Abercromby was made judge-advocate-general, and chief baron of the exchequer of Scotland in 183o, when he resigned his seat in parliament. He joined the cabinet of Earl Grey in as master of the mint. In the new parliament of 1835, Aber cromby was elected speaker of the House. As speaker he was not very successful in quelling disorder, but he introduced several important reforms in the management of private bills. On his resignation in May 1839 he was created Baron Dunfermline of Dunfermline. He died at Colinton House, Midlothian, on April 17, 1858, and was succeeded in the title by his only son, Ralph. See Spencer Walpole, History of England (London, 189o) ; Greville Memoirs, edited by H. Reeve (London, 1896) ; Lord Cockburn's Journal (Edinburgh,