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THE SCOTTISH GEOGRAPHICAL MAGAZINE. A GEOGRAPHICAL DESCRIPTION OF THE COUNTY OF AYR. 1 By T. M. STEVEN. (With Ma2.) Geological Str~Jcture.--For illustrating those principles which underlie modern conceptions of geography, the county of Ayr possesses many advantages. Its general position and place relations provide an excellent commentary on the change of geographical values in modern times; its boundary and lines of communication are of quite typical nature, and their effect may be traced in national as well as in local history; while its interests and resources are so Varied and so well balanced that most types of Scottish scenery and industry find their counterpart, even if only in miniature, within the narrow limits of a single shire. Variety, indeed, is the most characteristic feature of the Ayrshire of to-day; the pursuits of agriculture, shipping, mining, and industry which mark various stages in its economic development have been preserved side by side, partly by a kind of industrial inertia, but still more by the persistence of favourable conditions. And through all the variety runs a strange balance, so that no one interest wholly commands the prosperity of the county. Underlying the variety, and determining the balance, there is the far-reaching effect of geologlcal structure. This it is which acts alike in scenery and agriculture and industry, binding all into a coherent and geographical unity: and with this a geographical description may most naturally begin. 1 This essay was awarded the silver medal offered by the Society for competition in the Geography Class at Edinburgh University during 1911. VOL, XXVIII. 2 F 394 SCOTTISH GEOGRAPHICAL MAGAZINE. The greater part of Ayrshire lies in what is known as the Midland Valley of Scotland. This is a true rift valley, whieh formed an area of subsidence in Old Red Sandstone times, and in which younger formations have been preserved. No trace, indeed, can be found of Mesozoic or Tertiary rocks; but the Lower Old l~ed, Upper Old Red, and Carboniferous systems are represented, while in Ayrshire there remains a small basin of Permian age. Denudation is mainly responsible for the present exposures of these formations, and has conferred on them no small degree of symmetry. Thus the great boundary faults which bring them down against the older rocks of the Highlands and the Southern Uplands run across the country from south-west to north-east. Lining each fault is a belt of rocks of Old Red Sandstone age; and between these belts lies the Carboniferous system of Scotland. The coal measures, one of the youngest members of the Carboniferous group, appear towards the centre of the valley. Even there, however, they have yielded to the agents of denudation, and in places older rocks have been exposed. Thus the coal-fields of Scotland occupy little basins to some extent protected by a hard rim of older igneous material which passes from the long line of the Sidlaws, Ochils, and Campsies into the Kilbirnie Hills between Ayrshire and Renfrewshire, turning then south-eastward to form a high moorland tract between the Clyde and its firth. It is in the light of this more general distribution that the geology of Ayrshire is most easily and most profitably read. The southern fault of the great rift valley runs from Girvan on the coast to New Cumnoek on the inland boundary of the county. South of this line the rocks are Silurian. The two divisions of the Old l~ed Sandstone age are both represented ; in the south by a stretch of country from Girvan to the Heads of Ayr and from New Cumnoek to Darvel, in the north by a fringe of coast from Wemyss Bay to Ardrossan. These are overlain, however, in places by the Carboniferous series, which isolates geologically the district round Maybole from that round Lanark and the northern fringe from the main Old P~ed belt. The little Permian basin lies unconformably over this at Mauchline, about the middle of the county, and is protected by a rim of igneous rock of the same age. Round this appear in order the various members of the Carboniferous group, the limestone series being extensively developed in the north of the county. The outermost layer is represented in the north and east boundaries by igneous rocks of Calciferous Sandstone age; and beyond this rim the reverse order is followed into the coal-basin of Lanarkshire. Sce~e~'y.--Denudation has had a physical as well as a geological effect on the county. The hard Silurian and igneous rocks have been carved, indeed, but roughly and unsteadily, while the softer beds of the coal-measures have been planed down with merciless severity. The sea, too, has sought out the weakness that was opposed to it; for the waves that beat in vain upon the sandstone cliffs of the north, or lose their energy in hollowing out the coves and crannies round Ballantrae, have eaten into the heart of Ayrshire to form the wide, sweeping bays of Irvine and Ayr, giving, together with the A GEOGRAPHICAL DESCRIPTION OF TI=IE COUNTY OF AYR. 395 circular trend of the inland watershed, its characteristic crescent form to the county. In the inside of this crescent lies the lower ground of Ayrshire, sloping gently to the south-west from the limestones of Kilbirnie and Beith, and stretching southward in long undulations over the coal-measures from Kilmarnock and Kilwinning to Cumnock and the Heads of Ayr, the regular outlines broken only where some isolated neck of igneous material forms a local eminence. Round this, like a skin, clings an almost continuous belt of higher ground. Scarcely reaching 1000 feet above sea-level in the bleak moors of the north-east, but' more rugged in the Old Red Sandstones on either side of Muirkirk, it rises in the Silurian rocks till an almost uniform height of 2500 feet is maintMned along part of the south-eastern boundary. In this southern district the only lowland strips are Mong the river valleys, where the Doon, the Girvan, the Stinchar, and the Dusk wind among the fertile haughs of alluvium they have themselves laid down. From such a point as the old Roman camp crowning the volcanic neck above Dundonald, much of this surface lies expanded to the view : for the county is nowhere broader than. 26 miles, or longer than 55, though the coastline with its points and bays extends to 84. Away in the north can be seen tile curious terraced outlines of the hills above Largs. Harmonising with the rounded form of the Great and Little Cumbraes in the Firth of Clyde, they rise in a series of humps to the north-east, and mark successive eruptions of volcanic material. East- ward, crowning the long, straight valley of the Irvine, rises the historic cone of Loudoun Hill, in form and isolation balancing the mighty mass of Ailsa Craig which lies far out in the Firth. On either hand rolls the fertile lowland, its little crests adorned with clumps of trees---a landscape monotonous to some minds, but with an air of comfort and prosperity born of the sweeping fields of green pasture or ripening grain, and of tile distant wisps of smoke that betoken towns and industry. Southward the gentle folds rise slowly to the sandstone hills above Maybole, over which, rugged and more abrupt, peeps line upon line of the Southern Uplands. The scenery of the coast does but present, as it were, the interior in section. The hilly ground descends to the shore in steep bluffs, as on either side of Largs; the igneous rocks break out in towering cliffs at the Heads of Ayr and Culzean Bay, or in a pieturesque confusion of points and coves round Ballantrae, or jut out to break the featureless regularity of the bays, like the curving promontory in whose shelter lies the harbour of Troon. But a new effect has been introduced by what is geologically a comparatively recent upheavM of the land, when the plain of marine denudation, carved out and levelled under the waves in the dim past, was slowly uplifted to a height of about 25 feet. Other terraces or raised beaches of this kind may, indeed, be traced in various parts of the county, but to none of them is a like economic importance attached; for on this strip are built the coastal towns of Ayrshire with their numerous interests and activities, and along this strip lies a remarkable line of transport and communication. Extending to a breadth of two miles over the softer strata between Irvine and 396 SCOTTISH GEOGRAPHICAL I~AGAZINE. Troon, and nat~owing in the north and the south, where a few yards had been laboriously gained by the ceaseless fretting of the waves ; concealed and made irregular by the great accumulations of blown sand at Turn- berry and in the bays of Irvine and Ayr ; interrupted in places by the great intrusions of Bennane Head and the cliffs south of Ballantrae, this strip still forms an essential and characteristic feature of the scenery. The road along this, which ranks with the river-valleys as a line of communication of the first importance, curves inland to avoid the obstacles, or rises to surmount them; and at its side rise the steep bluffs of the old sea-front, beyond which is a perfect switchback of undulations. The Ice Age represents one of the latest of the great agents affect- ing the scenery of our country; but while its effects can easily be traced in Ayrshire, they have been felt rather in its agriculture than in its scenery.