154 PROCEEDINGS OF THE ACADEMY OF [1895. 



gulf. " 80 Others, again, ascribe to the lignites a swamp or lagoon 

 formation aud favor the theory that the greater portion of the neces- 

 sary vegetation grew where the lignite is now found. Dr. Penrose 

 attributes their origin in Texas to bayous and lagoons on the coast 

 and says: "Such places were probably heavily timbered and year 

 after year the trees dropped their leaves and dead branches on the 

 moist ground. Here they collected and were mixed with dead reeds, 

 moss, grass, etc. As the trees themselves died, they also lay down 

 in the same grave and rotted in the same boggy waters as their 

 leaves and branches, until often a great thickness of decayed veget- 

 able matter had been collected." 81 Another theory might be added. 

 These lignite beds grew upon the exact spots iu which they are now 

 found and are due to the swampy condition of the region, but the 

 material contributing to their structure did not consist of large trees 

 but rather of the growth of small marsh plants such as are found in 

 the underlying clays, that the presence of tree trunks in these beds 

 is largely adventitious and brought in during periods of inundation. 

 When the plant growth became strong enough to support arboreal 

 vegetation small trees undoubtedly did grow in some portions of the 

 lagoon but never to such an extent that they could contribute much 

 toward the formation of the great lignite deposits as we now find 

 them. 



To the first of these theories, that the beds of lignite are due to 

 accumulations of land vegetation carried out to sea, there are many 

 and serious objections. In the first place, we have the wide, almost 

 universal distribution of these lignite beds, their great thickness in 

 many places, their exact superposition one above the other for at 

 least six times, their general purity and the utter absence of fossils. 

 Passing over the question of the enormous amount of vegetation 

 necessary to be carried out to sea to form these beds we are con- 

 founded with the question of their superposition. In order to ob- 

 tain this we have to suppose a series of undulations of uniform eleva- 

 tion and subsidence with a uniform series of currents having equal 

 powers of transportation, extending through an enormous length of 

 time. It will also be necessary to suppose long periods of cessation 

 in the deposition of vegetable matter and during which great thick- 



80 Geol. Survey of Ark., Vol. II, of 1888, p. 60. 



31 Geol. Survey of Texas, First Annual Report, 1889, p. 91. 



