Acid and Intermediate Intrusions and Associated Ash-Necks in the Neighbourhood of Melrose (Roxburghshire)

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Abstract
I. Introduction. The igneous rocks under consideration fall within an area about 7 miles square, included in Sheet 25 of the Geological Survey's 1-inch map of Scotland. It is generally believed that they date from a late period in the history of the ‘Plateau Eruptions’ of Calciferous Sandstone times, and correspond with the trachytic lavas and intrusions of the Garleton Hill district (East Lothian), and with the similar intrusions in the Campsie and Renfrewshire hills. The only new evidence obtained, bearing upon this suggestion, weakens rather than supports it: a small neck, the Little Hill, including ash and plugged by basalts of two types, has been found within the Eildon complex of felsitic and trachytic rocks, and is almost certainly of subsequent origin. But it should be borne in mind that the admittedly-late felsitic and trachytic intrusions of the Campsie Fells are in certain cases cut by still later basalts. The restricted area over which acid rocks of this suite extend in the various districts of Scotland in which they occur is partly due to extreme denudation, and partly to the viscous character of their magma. Only in the Garleton Hills are extensive lavaflows preserved. It seems fairly certain to me that Dr. Peach is right in regarding none of the Melrose rocks as lavas, although the evidence does not altogether exclude the possibility of lavas entering into the Eildon complex. The rocks may be grouped, according to their field-relations, as follows :— Laccolites and sills.—White Hill; Black Hill; Bemerside;

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