86 J. S. GAEDNEE Olf THE LOAVEE EOCE]vrE PLA2^T-BEDS 



it ; but the rest of the hill is masked by Boulder-clay. The horizon 

 of the leaf-bed must, however, nearly approximate to that of 

 Ballj^alady. 



The adit is level, and after piercing about 30 feet of Boulder-clay, 

 reaches a compact sandy clay in which the plant-remains occur. 

 Beneath this is an indurated micaceous sand, the base of which is not 

 exposed, so that its thickness cannot be measured. The miner 

 whom T employed stated that the base was lithomarge, but he did 

 not know how deep down this occurred. The leaf-bed itself occurs 

 at the angle of a cross-cut and does not reappear on the opposite 

 faces ; it is bounded on one of the remaining sides by the Boulder- 

 clay, and on the other by a slight downthrow, so that its superficial 

 extent is very limited. The bed is about six feet thick, but well- 

 preserved leaves are confined to about one foot, where the matrix is 

 whiter and more laminated clay. The rest of the bed is greyer and 

 more sandy, and contains dark and ill-defined impressions of leaves, 

 limbs, and trunks of trees, and extends a considerable distance into 

 ' the mine. Above this is a singular conglomerate of well-rounded 

 pebbles of very hard clay in an equally indurated paste. The 

 surfaces of these pebbles are here and there polished and striated by 

 pressure, and darkened so that they exactly resemble flints to the 

 eye. This conglomerate is succeeded as well as sometimes replaced 

 by coarse quartz-grits, the grains being always cemented by the 

 same paste. These and the grey micaceous sandy clay are at least 

 30 feet in thickness. The bauxite rests upon this and also contains 

 masses of lignite and lignitized wood. Deeper in the mine it 

 becomes blotched with red and gradually passes into an iron-ore, 

 which also overlies it, and which, with a band of lignite, completes 

 the series of sedimentary deposits up to the basalt. The lower parts 

 of the deposit were undoubtedly formed by running water of some 

 swiftness ; but the upper parts (the lignite, the bauxite, and iron-ore) 

 are the results of more tranquil deposition. The bauxite may be 

 the finer residuum from the decomposition of granite, or of basalt, 

 with the iron &c. removed by some natural process; but it is 

 evidently not Geyserian, as the bauxites of France have been 

 surmised to be. 



The Ballintoy Leaf -bed. 



The leaf-impressions are found in compactly laminated lignite, and 

 the leaves present a somewhat glistening surface in contrast to the 

 dull black of the matrix*. Wood-structure is also well preserved, 

 and can be recognized as coniferous. The lignites are here directly 

 overlain by the basalts, but rest on carbonaceous clay with rootlets 

 in the usual manner. Their thickness appears to vary from 2 to 5 

 feet ; but they are, in places at least, separated into two beds by 

 intervening clay. The beds extend for some distance, and the 



* Traill mentions the occurrence of plants in the clay under the lignite, but 

 I have not myself come across any in this position. He places the lignites of 

 Ballintoy at some 30 to 40 feet above the bole. 



