the fresh- water which covered the Upper Portland beds. 

 They indicate the commencement of the delta which 

 extended over a great part of south em England, and 

 extended to Germany. The Skull-cap, a bed from 1ft. to 

 3ft. in thickness, lying upon the topmost bed of the Port- 

 land, beds is succeeded by a thin seam of black earth, 

 which is barren of vegetable remains in Portland, but at 

 Eidgway, where it is only a few inches thick, it contains " 

 the trunks of large trees having the appearance of 

 being much decayed externally, with none of the bark 

 preserved. A laminated fresh-water limestone, about 

 eight feet in thickness, divides it from the famous Black 

 Dirt, or Dirt Bed, which is about a foot thick, consisting 

 of a dark loam, containing a large proportion of earth, 

 lignite, and water-worn stones. It must have supported 

 a luxuriant vegetation, for in and upon it are numerous 

 remains of coniferous and cycadeous trees, lying partly 

 in the black earth and partly covered by the super- 

 jacent calcareous bed, having the appearance of dome- 

 like concretions which surround the stumps. Of these 

 there are good examples about a quarter-of-a-mile East 

 of Lulworth Cove. The trees are still erect with their 

 roots in the vegetable soil, and broken off a short 

 distance from the ground. A submergence, or change 

 of level, converting the high lands, on which the trees 

 grew into a morass, would inevitably cause the 

 destruction of the forest, and occasion a rapid decay, 

 especially at the bases of the trees, and, thus weakened, 

 they would yield to the force of wind or flood, and 

 break off a few inches from the root. The Dirt Bed is 



