I NT ROD UCTION. I 7 



pit-coal, and often inclosing pieces of wood in good preservation, is widely 

 diffused through the strata of the Tertiary and Quaternary formations. 

 There is no doubt that it has usually proceeded from substances of the 

 same character as our modern peats. All intermediate states are found 

 between true lignite and normal marsh peat or lake peat with pieces of 

 wood and stems of trees occasionally imbedded in them. The connection 

 is established especially by the slate-coal, as it is termed, of the Quaternary 

 formations of Utznach and Diirnten in the north of Switzerland, and in 

 Upper Bavaria. Proof of this is supplied at great length by Heer J and 

 Giimbel 2 . Lignite occurs in many cases, as is well known, in rotten 

 crumbling masses, which must be pressed in moulds before they can be 

 used ; in other cases it contains less water and has a slaty cleavage, but 

 is still tolerably homogeneous. The formation of all the above coals finds 

 an immediate parallel in that of the peat of our lake-marshes. But this is 

 not the case with the lignite from other formations, which is composed for 

 the most part, sometimes almost exclusively, of accumulations of well- 

 preserved stems of trees capable of being split like firewood, and occasionally 

 alternates with layers consisting entirely of leaves. These deposits were 

 doubtless formed in a different manner, but in their case also we have 

 thoroughly suitable objects of comparison from our own times. We may 

 cite first the colossal masses of tree-stems which are carried down by the 

 great American rivers, the Mississippi, for example, and the Mackenzie, and 

 deposited in lagoons in the lower part of their course, and in the stagnant 

 waters of their deltas. Entire layers of such stems are actually found in 

 the delta of the Mississippi buried deep in sand and mud, which though 

 belonging to the most recent alluvial strata have already assumed the 

 character of a true brown coal 3 . That this alteration of recent wood sets 

 in very quickly may be gathered from various observations. For instance, 

 some wrought timbers, buried in the c Old Man ' of the Rammelsberg, in 

 the mine of St. Joachim near Zellerfeld, and in that of Dorothea near 

 Clausthal, were disinterred according to Hirschwald 4 and Hausmann 5 one 

 hundred to one hundred and fifty years perhaps after they were put up in 

 the mines, and were found to be in a soft and moist condition, but when dry 

 they proved to have been converted into a lignite of a black colour and 

 lustrous corichoidal fracture. Goppert had before observed timbers in the 

 coal-mines of Charlottenbrunn, which after being kept in them for a long 

 time were converted into lignite. Unger 6 has described a piece of wood of 

 this kind from the iron-mines of Turrach in Styria, which had suffered a 

 similar alteration, as was shown by analysis. But the most striking proof 

 of the shortness of the time required has been supplied by Mietzsch 7 . He 



1 Heer (16). 2 Giimbel (2). 3 Lyell (1), p. 242. * Hirschwald (1). 



Hausmann (1). 6 Unger (6). 7 Mietzsch (1), p. 234. 



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