I91I.] STEVENSON— FORMATION OF COAL BEDS. 17 



of coal, it may be inferred, that such clay stratum could not have 

 been the soil, where grew the vegetable matter which produced the 

 coal, unless this vegetable matter was a moss, a peat, or some aquatic 

 plant; because in the clay, there is no appearance of trunks, or 

 other vegetable impressions, beyond slender leaves, as of a long 

 grass." 



Lyell-^ about this time committed himself in part to both hypoth- 

 esis, though evidently disposed to favor that of transport. " The 

 coal itself is admitted to be of vegetable origin and the state of 

 the plants and the beautiful preservation of their leaves in the 

 accompanying shales precludes the idea of their having been floated 

 from great distances. As the species were evidently terrestrial, we 

 must conclude that some dry land was not far distant ; and this 

 opinion is confirmed by the shells found in some strata of the New- 

 castle and Shropshire coal-fields." The alternation of marine lime- 

 stone with strata containing coal beds may be due to alternate rising 

 and sinking of large tracts, which were first laid dry and then sub- 

 merged again. He is clearly inclined to agree with the suggestion 

 made by Sternberg and Ad. Brongniart, that the beds of mineral 

 detritus were derived from waste of small islands arranged in rows 

 and he thinks that the suggestion is supported by the observation 

 that the Coal Measures flora is of insular type. 



At a later period, Lyell accepted the autochthonous origin of 

 the coal beds, as appears in the " Travels in America." 



Buckland,-'' in 1836, accepted the theory of transport. " The 

 most early stage to which we may carry back its origin was among 

 the swamps and primeval forests, where it flourished in the form of 

 gigantic Catamites and stately Lepidodcndra and SigillaricE. From 

 their native bed, these plants were torn away, by the storms and 

 inundations of a hot and humid climate and transported in some 

 adjacent Lake or Estuary or Sea. Here they floated on the waters, 

 until they sank saturated to the bottom, and being buried in the 

 detritus of adjacent lands, became transferred to a new estate 



^^C. Lyell, "Principles of Geology," 5th ed., 1st Amer. ed., Philadelphia, 

 1837, Vol. L, p. 134. 



^®W. Buckland, "Geology and Mineralogy considered with Reference to 

 Natural Theology, Philadelphia, 1837, pp. 362, 353, 354. 



PROC. AMER. PHIL. SOC. L. I98B, PRINTED APRIL 24, I9II. 



17 



