1919 ^'fJOJ ^" ^^9 Succession 199 



dead trees^ probably killed by the advance of Sphagnum, while such a con- 

 dition was rarely found at Carlisle and the cause of death seemed less 

 evident. The layer of organic matter on the Yakutat prairie is about 

 30 cm. (1 foot) deep and rests upon very coarse gravel, evidently glacial 

 outwash. The soil of the prairies of Grays Harbor county (Mangum 

 1912) is Montesano silty clay loam (the mucky phase in several areas). 

 The soil owes its origin to the decomposition of sandstone, basalt and 

 shale gravels, which were elevated during Pleistocene time. The original 

 material has been considerably modified by weathering and the accumula- 

 tion of much organic matter which has resulted from restricted drainage 

 conditions. The flora of the Yakutat prairie has been previously described 

 (Rigg 1914.) 



Sphagnum in a hardhack swamp 



In some cases there occur depressions which are undrained and the 

 major portions of which are carpeted with an extensive growth of Sphag- 

 num, and yet no bog has been formed, since the layer of decayed and 

 decaying moss beneath that which is living is insignificant, and none of 

 the other plants that characterize the bog stage are present. Sphagnum 

 is there, the lack of drainage is there, but sufficient time for the formation 

 of a sphagnum bog has not yet elapsed. 



An undrained depression about 2 hectares (5 acres) in extent near 

 Covington, Washington, illustrates this early stage in bog development. 

 Water finds no outlet whatever from this depression until it is perhaps 

 60-90 cm. (several feet) in depth. It is stated by those familiar with the 

 region that water is commonly 60 cm. (2 feet) or more in depth in this 

 depression in winter, and that it does not disappear until August. The 

 soil (Mangum 1911) in which this depression occurs is derived from 

 glacial drift and has been more or less worked over by glacial waters. It 

 is Everett gravelly loamy sand. This soil "is derived mainly from the 

 coarser glacial deposits of sand and gravel which were laid down by the 

 waters of the melting ice, but some of these gravelly areas probably rep- 

 resent the glacial drift, modified by the action of glacial waters, which 

 have removed the finer material and left the coarser sand and gravel, de- 

 posited in beds, pockets, and strata of various degrees of thicknes. The 

 drainage of this type of soil is too thorough." 



The visits of the writer to this depression were made on October 21 

 and November 17, 1917. There was no water in the depression on either 

 cf those dates though the substjatum was thoroughly watersoaked on the 

 latter date. It seems probable that this depression is not free from stand- 

 ing water for more than three months of the year on the average. The 

 time that it is free from water is not the normal growing season for any- 



