224 CONFERENCE ON PALEOZOIC PALEOGEOGRAPHY 



While the striking instances cited from the reports just mentioned^ 

 are important as showing both the distance to which vegetal refuse may, 

 under favorable circumstances, be deposited, and the depth at which it 

 may be found in terrigenous deposits, two important points should not be 

 lost from view: first, that most of the material is found in regions of 

 deposition of terrigenous matter, and, second, that in most cases the 

 localities are in close proximity to the land. Even in the latter cases the 

 organic matter is described as more or less decayed, while in the most 

 remarkable series, extending over a stretch of 500 miles or more from the 

 Central American coast to the Galapagos Islands, we find that all the 

 material was "in varying stages of decomposition." At best the leaf frag- 

 ments reported appear to have been confined to types with hard, siliceous, 

 or thick cuticles, such as the palm and the bamboo. Only thick, leathery, 

 dicotyledonous types like the orange and the mangrove seem to have been 

 in recognizable condition in the dredging near the land. Only in very 

 rare cases do we find any quantity of land plant material under the con- 

 ditions of deposition of the purer carbonates at any considerable distance 

 from the coast, and in these cases the material embraces only the more 

 imperishable parts of the plants. 



The significance of the evidence offered by plant remains found fossil 

 in marine deposits depends mainly on the state of their preservation. If 

 the material is macerated, corroded, rolled, defoliated, skeletonized, in- 

 crusted, or bears other signs of having been for some time in the water, 

 it is liable to have been transported for some distance, judgment of the 

 possible distance or time being dependent to an extent on the progress of 

 the work of the destructive agencies. If long in sea water the fragments 

 are likely to bear the marks of the abundant marine organisms, particu- 

 larly if in tropical sea water. On the other hand, the occurrence of clean, 

 unbroken, smooth leaves, and particularly of large segments of fern 

 fronds, with their full complement of carbonaceous residues, is prima facie 

 evidence of minimum exposure to water and of the least subjection to the 

 action of swift currents or waves. In fact, it may be stated that except 

 in extraordinary or most fortuitous cases clean and distinct leaves are 

 never found in limestone strata, whether marine or fresh water, except 

 in a very near relation to the land on which they had origin. Farther 

 from land they are more indistinct, poorly preserved, fragmentary and 

 deformed, as well as wasted. In most marine sediments the only vestiges 

 of land plants that may be found are confined to the most Indestructible 



8 For illustrations of long transportation see Lyell : Principles of geology. 1867, vol. 

 ii, p. 361 ; vol. i, p. 445 ; Challenger narrative, vol. i, pt. 2, p. 679 ; Bates : Naturalist 

 on the River Amazon, 1863, p. 389. 



