The Philosophical magazine; a journal of theoretical, experimental and applied physics . ce derivedfrom fossils is unfortunately not applicable, as I was unableto find a trace of any organic substance either in the limestone,sandstone, or shale; and the same statement has been madeby Dr. MacCulloch. It is probable, however, that organicremains will yet be found on a more extended and carefulsearch. vf the Island of Bute. 85 III. The Lignite Beds. 7. The trap rocks at Ascog derive their chief interest frombeing the repository of beds of lignite; a substance so rare inScotland, that I believe no
The Philosophical magazine; a journal of theoretical, experimental and applied physics . ce derivedfrom fossils is unfortunately not applicable, as I was unableto find a trace of any organic substance either in the limestone,sandstone, or shale; and the same statement has been madeby Dr. MacCulloch. It is probable, however, that organicremains will yet be found on a more extended and carefulsearch. vf the Island of Bute. 85 III. The Lignite Beds. 7. The trap rocks at Ascog derive their chief interest frombeing the repository of beds of lignite; a substance so rare inScotland, that I believe no well-marked beds occur on themainland, and but few in the other islands; and these insituations very difficult of access. I was led to a careful ex-amination of this carbonaceous deposit by the statement ofDr. MacCulloch, that some of the beds occurring here wereunlike any he had seen in his survey of the western islands. The principal bed is situated in the face of the cliffs abovethe road, a little to the south of Ascog Mill, as shown in theannexed section giving the various s, sandstone; r, terrace and road; ff, greenstone; a, trap-tuff; b, redochre; c, lignite bed; d, pisolitic ochre; e, porphyritic amygdaloid, theupper portion much-altered. The lowest bed resting on the sandstone is a small-grainedrudely columnar greenstone; the junction is, however, con-cealed. Over this is a trap-tuff with a base of greenstone,and imbedded spherical lumps of the same substance. Thisis followed by a bed of red ochre of coarse texture, traversedby numerous black iron seams, which have doubtless beenproduced from a change in the oxidation of the componentiron. Over this is the lignite bed: it is three feet thick, andconsists of hard stony coal, with a yellowish-white shale, both being much intermixed with pyrites. Thecoal has been so much altered throughout its whole thicknessby the contact of the trap rock, that Mr. Rose of Edinburgh,to whose examination I submitte
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