STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 51 



section in the valley of the Somme. The deposit is 8 feet thick in 

 13 wholly distinct benches, varying in thickness from one third to 

 one meter. Four benches, aggregating 2 meters, are of excellent 

 peat, but the others are, in several cases, little better than carbona- 

 ceous shale; the ash is calcareous. Similar illustrations are to be 

 found in the American treatises. 



In areas where floodings of muddy water are wanting and where 

 climatal variations show little change from year to year, there may 

 be no benches and the mass may be continuous from bottom to top. 

 Johnson**' has described a peat deposit, which shows about 15 feet 

 of sphagnum-peat, practically continuous. Cook,*^ in discussing the 

 bogs of New Jersey, states that the peat is so crowded with logs of 

 CJianicrcvparis that one has difficulty in thrusting a sounding rod 

 to the bottom. The condition is the same throughout, even where 

 the peat is 13 feet thick; the Waldmoor growth was uninterrupted. 

 A similar story is told by the cypress swamps. R. M. Harper and 

 others have shown that, in the cypress swamps of Florida, the peat 

 is so filled with logs and woody roots as to be without commercial 

 value. Lyell's*^ statements respecting the cypress swamps of the 

 Mississippi region are in similar terms ; for he says that the con- 

 tractor, in excavating for foundations of the New Orleans gas 

 works, soon discovered that he had to deal not with silt but with 

 buried timber; the diggers were replaced with expert axemen. The 

 cypress and other trees were " superimposed one upon the other, in 

 an upright position, with their roots as they grew." The State 

 Surveyor reported that, in digging the great canal from Lake 

 Ponchartrain, a cypress swamp was cut, which had filled gradually, 

 " for three tiers of stumps in the nine feet, some of them very old, 

 ranged one above the other ; and some of the stumps must have 

 rotted away to the level of the ground in the swamp before the 

 upper ones grew over them." It should be said that the whole 



du literal Flamand et du Departement de la Somme," Mem. Soc. Set. Lille, 

 Vol. XL, 1872, pp. 471, 472. 475-478. 



■**5 D. W. Johnson, " The Shoreline of Cascumpeque Harbor, Prince Ed- 

 ward Island," Geogr. Journ., 1913, pp. 152-164. 



4^ G. H. Cook, " Geology of New Jersey," 1868, pp. 301, 355, 360, 484. 



48 C. Lyell, " Second Visit to the United States of North America," Lon- 

 don, 1850, Vol. II., pp. 136, 137. 



