568 STEVENSON— FORMATION OF COAL BEDS. [November 3, 



of the Imbugahi is such a grass-covered area, and here excavations 

 by the side of the raih'oad show that a bed of peat has accumulated, 

 which is two feet thick in some places." It is difficult to understand 

 on what grounds a recent writer feels justified in asserting that this 

 is probabh' bituminous shale. Hartt knew peat and he knew bitu- 

 minous shale when he saw them. On the authority of the engineer 

 who constructed the railroad in Sao Paulo, Hartt states that near 

 Tumanduathy the land spreads out between the hills, level as a lake 

 and about two miles wide, covered with deep 'layers of black soil 

 " fibrous and woody like peat." The railroad was built over the 

 surface of this bog, but no eft'ort was made to determine the thick- 

 ness of the deposit. • 



Mrs. Agassiz, cited in another connection, gives evidence respect- 

 ing present conditions in Brazil. Kuntzc''" has described the for- 

 ested swamps on the divide between the Amazon and the Paraguay. 

 High water makes ponds on the broad alluvial plain, in which Ponte- 

 deria and other plants settle. The ponds become filled with silt and 

 humus and a swamp flora, rich in palms, takes possession of the sur- 

 face. The Lourenqo or Cuyaba river, rising in the low divide, 

 unites with the Paraguay at about S. L. 18°. This river, for about 

 three degrees of latitude, flows through the vast wooded Guatos 

 swamp, which Kuntze thinks is, at least in part, a floating bog. He 

 gives no estimate of thickness, but his brief statement leaves no 

 doubt that the mass is very great. The material is true peat, for in 

 another part of his work he speaks of the fragments of peat occa- 

 sionally torn off from the mass. The invasion of streams by grasses 

 is rapid and complete throughout this region. Kuntze notes this. 

 Morong,''' in speaking of his attempt to reach the head of Pilcomayo 

 river in S. L. 22°, says that his progress was stopped in a lagoon, 400 

 miles from the Paraguay river, by a dense growth of grasses and 

 weeds, one species of the former attaining the height of 5 meters. 



The great accumulations in the lowlands of Nicaragua and Costa 

 Rica have been mentioned by several authors and the writer knows 



"" O. Kuntze, " Gcogenctische Beitriige," Leipzig, 1895, pp. 5, 67, 70. 

 «'T. Morong, Ann. N. Y. Acad. Sci., Vol. VII., 1892, pp. 45, 260. 



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