Columnar basalt, 40 feet. Position of first leaf-bed, obscured by grass, about 2 feet. Gravel varying from about 25 feet to a maximum of nearly 40 feet. Black or second leaf-bed, 2-1/2 feet. Gravel about 7 feet. Grey clay, 2 feet. Laminated sandstone, 6 inches, with 3 inches of fine limestone, containing leaves at the base. Clay, with leaves at base, 1 foot. Clunch, with rootlets, 7 inches. Amorphous basalt, becoming columnar at base, about 60 feet. [Footnote 242: _Op. cit._ p. 280.] Mr. Starkie Gardner has called attention to the extraordinarily fresh condition of the vegetation in some of the layers of the Ardtun section. One of the leaf-beds he has found to be made up for an inch or two of a pressed mass of leaves, lying layer upon layer, and retaining almost the colours of dead vegetation. Among the plants represented is a large purple _Ginkgo_ and a fine _Platanites_, one leaf measuring 15-1/2 inches long by 10-1/2 broad. The characteristic dicotyledonous leaves at this locality possessed relatively large foliage.[243] [Footnote 243: For fuller local details regarding the Ardtun leaf-beds, I may refer to the original paper by the Duke of Argyll (_Quart. Jour. Geol. Soc._ vii. p. 89), and to the memoir by Mr. Starkie Gardner (_op. cit._ xliii. (1887), p. 270).] To the early observations of Macculloch we are indebted for the record of an interesting fact in connection with the vegetation of the land-surface over which the first lava-flows spread. He figured a vertical tree trunk, imbedded in prismatic basalt, and rightly referred it to some species of fir.[244] This relic may still be seen under the basalt precipices of Gribon. Mr. Gardner found it to be "a large trunk of a coniferous tree, five feet in diameter, perhaps _Podocarpus_, which has been enveloped, as it stood, in one of the flows of trap to the height of 40 feet. Its solidity and girth evidently enabled it to resist the fire, but it had decayed before the next flow passed over it, for its trunk is a hollow cylinder filled with debris, and lined with the charred wood. A limb of another, or perhaps the same tree, is in a fissure not far off."[245] [Footnote 244: _Western Islands_, vol. i. p. 568, and plate xxi. Fig. 1.] [Footnote 245: _Quart. Jour. Geol. Soc._ xliii. p. 283.] At different levels in the volcanic series of Mull, beds of lignite and even true coal are observable. These seem to be always mere lenticular patches, only a few square yards in extent. The best example I have met with lies among the basalts near Carsaig. It is in part a black glossy coal, and partly dull and shaly. Some years ago it was between two and three feet thick, but now, owing to its having been dug away by the shepherds, only some six or eight inches are to be seen. It lies between two basalt-flows, and rapidly disappears on either side.