It appears, therefore, that though there is sometimes extraordinary local diversity in the direction of the dykes in those districts where they present the gregarious type, the general north-westerly trend can usually still be recognized. But when we turn to the long massive solitary dykes, we soon perceive a remarkable change in their direction as we follow them northward into Scotland. I formerly pointed out how the general north-westerly trend becomes east and west in the Lothians, with a tendency to veer a little to the south of west and north of east.[187] This departure from the normal direction is now seen to be part of a remarkable radial arrangement of the dykes. Beginning at the southern margin of the dyke-region, we have the notable example of the Cleveland dyke, which in its course from Cleveland to Carlisle runs nearly W. 15° N. The Eskdale dyke has an average trend of W. 32° N., and the same general direction is maintained by the group of dykes which run from the Southern Uplands across the south-west of Lanarkshire and north-east of Ayrshire. But proceeding northwards we observe the trend to turn gradually round towards the west. The dyke that runs from near the mouth of the Coquet across the Cheviot Hills to beyond Hawick has a general course of W. 8° N. In the great central coal-field of Scotland the average direction may be taken to be nearly east and west, the same dyke running sometimes to the north, and sometimes to the south of that line. But immediately to the north a decided tendency to veer round southwards makes its appearance. Thus the long dyke which runs from the Carse of Stirling through the Campsie Fells to the Clyde west of Leven, has a mean direction of W. 5° S. This continues to be the prevalent trend of the remarkable series of dykes which crosses the Old Red Sandstone plains, though some of these revert in whole or in part to the more usual direction by keeping a little to the north of west. Even as far as Loch Tay and the head of Strathardle, the course of the dykes continues to be to the south of west. Tracing these lines upon a map of the country we perceive that they radiate from an area lying along the eastern part of Argyleshire and the head of the Firth of Clyde (see Map I.). [Footnote 187: _Trans. Roy. Soc. Edin._ xxii. p. 651.] [Illustration: Fig. 241.--Section along the line of the Cleveland Dyke at Cliff Ridge, Guisbrough (G. Barrow). Scale, 12 inches to 1 mile.] 10. TERMINATION UPWARDS