The Solway Firth is the only important ria on the western coast of 1 Scotland; it has a complex history, for denudation and earthmovements of several different dates have contributed to its formation. Uncertainty as to the essential structure of the Solway valley at present renders doubtful its position in the valley system of Southern Scotland. The Solway—Carlisle basin is generally represented as occupying a synclinal between the Lower Palaeozoic hills of the Lake District and of the Southern Uplands of Scotland. Thus the sections by E. W. Binney (1865, p. 369, ref. p. 249) and Mr. T. V. Holmes (1889, p. 247, and 1899, pp. 22, 40) represent the valley of the Solway and its eastern continuation as lying along a synclinal and resting on a great thickness of Triassic rocks. The axis of the synclinal is marked by the Lias which occurs to the west of Carlisle. The Solway-Carlisle basin cannot, however, have such a simple synclinal structure, for Carboniferous rocks occur at the surface near the northern shore of the Eastern Solway. This fact is shown by a boring for coal made in 1794 in an old quarry beside the Kirtle Water at Redkirk Mill, 1£ miles to the south-west of Gretna Green. The bore journal was published in Singer's Agricultural Survey of the County of Dumfries, 1812, pp. 670-3 ; and as that book is scarce and the bore important the record may be conveniently reprinted.