HUMULITHS 485 



organic matter, either animal or plant. Fusulina limestones often 

 contain asphaltic material in abundance, and the same is true to a 

 certain extent of Stromatopora limestones, where the organic matter 

 may be represented by concentric films of asphaltum or other bitu- 

 minous matter. Nummulitic as well as nullipore limestones may, in 

 like manner, have a bituminous constituency. The finest calcilutytes 

 are often impregnated with bituminous matter, especially if, as in 

 the Upper Cambric of Sweden, they are intercalated in bituminous 

 shales (sapropelargyllites). Such rocks when struck with a ham- 

 mer give out a fetid odor which causes them to be classed as fetid 

 limestones, or "stinkkalk." IMetamorphism of limestones of this 

 type would result in the production of graphitic marbles. Sapro- 

 pelites in which silica forms the leading accessory constituent are 

 represented by diatomaceous oozes in which the decay of the or- 

 ganic matter has produced the bitumen. The Eocenic Menilite 

 shales of the Paris basin and the Oligocenic IMenilite shales of 

 Galicia are typical examples. The latter might perhaps be regarded 

 as the source of the petroleum of that region. Sapropelferrilytes 

 are bituminous iron carbonates such as are deposited under certain 

 conditions in some bogs. 



Recent Humuliths. 



These are formed by the growth in situ of plants, either such 

 as grow on the land or those living in marshes and swamps (autoch- 

 thonous) or formed from material rafted or drifted together (al- 

 lochthonous). Marshes, swamps, and bogs are the chief sites of 

 accumulation of such deposits at the present time, and a consid 

 eration of these must precede the discussion of the older deposits of 

 humuliths, /. c, the coals. 



In general we may adopt the word moor for all the surfaces 

 of land, whether high or low, which, with more or less wetness, are 

 covered by successive growths of vegetation, the remains of which 

 accumulate to form beds of peat. Three kinds of moor may be 

 distinguished : the marine low moor, or marsh ; the fresh water 

 low moor, or swamp ; and the upland moor, or bog. The restric- 

 tion of the terms here given, and in part at least advocated by 

 Shaler many years ago, will prove useful and make for precision. 

 Shaler {42:26-!) has given us a useful classification of modern 

 moorlands which, with some slight changes, chiefly rearrange- 

 ments, is as follows (Parsons-30) : 



