The Rev. W. Buckland on the Plastic Clay Formation, 303 



in diameter ; they retained a whitish colour like touchwood, and 

 were softer than the adjacent earth or moor log. The moor log 

 appeared at about three or four feet under the marsh ground, and 

 differed in thickness at different parts ; at Deptford it was six feet 

 thick ; at Woolwich Reach, opposite the ballast wharf, it was be- 

 tween seven and eight feet thick ; its thickness as well as its breadth 

 gradually increasing down the river. Beneath the moor log was a 

 stratum of blue clay, and under this gravel and sand. Stags horns 

 were likewise found in different places, a little above the vein of 

 moor log. 



Mr. Derham's account of the Dagenham marsh land (Phil. Trans. 

 1710, p. 478), affords the following particulars in addition to those 

 given by Capt. Perry. 



The stumps and roots of many trees were found in the same 

 posture in which they grew, situated in a soil consisting of a black 

 oozy earth, full of the roots of reeds ; the tops of these stumps 

 were so worn that it could not be ascertained whether the bodies 

 had been cut off by the ax, or broken by natural violence. The 

 bodies themselves lay horizontally on the surface of the oozy earth, 

 in confusion, but a northerly direction seemed most prevalent. 

 They appeared almost all of them to have been alder, though at 

 first they were supposed to be yew. Over the trees lay a covering 

 of grey mould, of the same nature with the sediment of the Thames 

 at this day, varying in thickness from seven to twelve feet. Mr. 

 Derham mentions the names of the following places in which he 

 noticed traces of this subterranean forest. Dagenham, Havering, 

 Rainham, Wennington, Purfleet, West Thorrock. 



It happened a few years ago that in cutting the canal and basins 

 in the Isle of Dogs, a subterranean forest containing hazel nuts, with 



2 Q2 



