On the origin of bright laminae in coal, and a suggestion arising out of their distribution

Abstract

Although the vegetable origin of coal is universally accepted, there are points presented by coal seams which still await investigation. This is particularly true in regard to the manner in which the vegetable matter accumulated. The fact that two theories have been brought forward to explain the precise mode of origin of coal shows that divergent views exist among geologists on this question. The difference of opinion, however, may be more imaginary than real, for a small experience of the occurrence of coals throughout a single coalfield convinces one that both the growth in situ and drift origins have obtained, and one may find that while in one place a coal seam has unquestionably resulted from an accumulation of vegetable matter which grew on the spot where it now rests, in the same district equally indisputable evidence may be found to show that another bed of coal was entirely derived from drifted vegetation. In the present paper, I propose to discuss the nature and origin of certain bright laminae which are a characteristic feature in all bituminous coals, and to suggest that from their distribution in a coal seam, evidence can be obtained to show that many beds of coal have originated by a combination of both the growth in situ and drift modes of origin. A piece of ordinary bituminous coal is made up of a series of bright and dull layers. The surfaces of the latter, if closely examined, usually show that they are almost entirely made up