Remarks on the geographical distribution of British plants : chiefly in connection with latitude, elevation, and climate /

Field: Earth and Planetary Sciences (Physical Sciences)

Tuart portion of the British Isles, to which the present treatise relates, will be understood to include the island of Britain, properly so called, consisting of England, Wales, and Scotland, and also the small isles immediately adjacent; but excluding Ireland, and the isles of Guernsey, Jersey, and Sark.Viewed separately, England, Wales, and Scotland run almost directly north and south; but nearly all Scotland lying to the west of a line drawn down the middle of England, the general direction of the whole island, from the south coast, is inclined considerably to the west of north.The longitudinal line of 2° W. from Greenwich cuts England into two nearly equal portions, eastward and westward, but scarcely touches Scotland ; 4° W. long.being nearly the mesial line of the latter.Hence no longitudinal line can be drawn along Britain, which shall entirely divide the eastern from the western B PHYSICAL GEOGRAPHY OF BRITAIN.coasts.In England and Wales, apart from Scotland, the line of 2° W. will do so pretty exactly.From Cornwall to Orkney the length of Britain is nine and a half degrees of latitude, or about 650 miles, extending between the parallels of 50° and 594°.Its breadth at the southern extremity is between seven and eight degrees; and near the northern extremity, from Caithness to the Western Isles, about four and a half.Connecting the adjacent isles and extreme points along the coast, the general form would be that of an irregular oblong, broader at the southern extremity; but so much is this intersected by bays, estuaries, and arms of the sea running far into the land, that in some places the eastern and western seas are scarcely one degree apart.By much the largest masses of land occur in England; yet there is perhaps no point in it more than sixty miles distant from the tides of the sea ; so that the whole island may be looked upon, almost literally, as maritime or coast-land; a peculiarity materially affecting its botanical productions.The distance of the south-eastern angle of England from the nearest point of Europe is little more than twenty miles.Hence they gradually recede from each other in a westerly and northerly direction, so that from Cornwall to Bretagne the distance is about one hundred miles, and the coasts of Scotland and Norway are much farther apart.Ireland fronts the western coast for a considerable extent, which would otherwise be entirely open to the Atlantic Ocean, as it is, notwithstanding, at the northern and southern extremities. ELEVATION OF SURFACE.The configuration of surface coincides with the geographical position, presenting a series of undulations or hills rising higher and higher as we advance from south-east ELEVATION OF SURFACE.$ to north-west, their general direction being nearly parallel to the coasts of the German Sea and channels connecting it with the Atlantic; but the courses of the particular groups or chains vary considerably, some being almost at right angles to a general line connecting the highest summits of each.The counties of England, from the southeastern angle northward to the Trent and Humber, westward to Dorset and Warwick, present only moderate undulations, seldom exceeding 300 yds, and never attaining 350 yds.In the north-east of Yorkshire, Egton Moors rise to 468 yds; Dartmoor in Devon attains to nearly 600 yds; and Exmoor exceeds 550 yds.Betwixt these are some other hills or groups between 300 and 400 yds of elevation, as the Cotteswold hills in Gloucestershire.But it is to the north-westward of the Severn and Trent that we find undulations of the surface rising to the rank of mountains.In the English counties bordering on Wales, as Salop, Worcester, Hereford, and Monmouth, the higher hills attain from 450 to 600 yds.In 8. Wales we see them (Beacons of Brecon) exceed 950 yds; and in N. Wales several summits of the Snowdon chain surpass 1000 yds, the peak of Snowdon itself rising to nearly 1200 yds.The Penine chain of the North of England attains 600 yds in Derbyshire, nearly 800 yds in Yorkshire, and on the borders of Cumberland is little short of 1000 yds.The Cheviot hills near the northern extremity of this chain, but more properly connected with the Scottish mountains, are rather below 900 yds.The central mountains of the Lake district in England exceed 1050 yds.The range or series of mountains crossing the south of Scotland, exhibits summits about equal to those of the Penine chain; and in the Highlands we have many exceeding 1000 yds, several above 1200 yds, and a very few passing 1400 yds.The highest points of England, Wales, and Scotland are near the western coasts, in the counties of Cumberland (Scawfell Pikes, B 2 2 a l PHYSICAL GEOGRAPHY OF BRITAIN.1055 yds), Carnarvon (Snowdon, 1190 yds), and Inverness (Ben Nevis, 1455 yds).The groups or ranges second in respect to elevation, as the Penine range and Cairngorm group, are more central.But it is only quite in the north of Britain that we find high mountains near the eastern coast.. From the western position of the loftiest mountains of England, Wales, and Scotland, the total absence of any mountain-like elevation in the south-east of England, and the second-rate mountains of England and Scotland being more central, and coming nearer to the eastern coast northwards, it follows that in a general view over Britain the gradual rise of surface, as already mentioned, is from south-east to north-west.This, however, applies strictly to the interior ranges of mountains only, or to the actual summits ; those near the western coasts being so deeply cut and divided by narrow valleys, that at the bases of the loftiest we find lakes and small flats of land scarcely raised above the sea level.The declivities of the mountains towards the north and west are consequently very rapid; while to the south or east they are much more gradual.The following list of the altitudes of hills, stations, &e. is compiled from various sources, as indicated by the letters in the first column after the names.In transcribing the list I have unluckily omitted and lost some few of the authorities.The rest are explained at the end of the list.It will be quite evident from the different estimates, which in some instances are given for the same hill, that the reputed heights of many of them admit of question : see the Ochils in Perthshire, Ben na Buird in Aberdeenshire, and West Lomond in Kinross-shire, for examples.** Asa recent example of the vague manner in which heights are ~ mentioned even in works of authority, we find Cader Idris called the second summit of Wales by the author of the Lncyclopedia of Geography, while the Trigonometrical Survey shows several others to be much loftier.