386 



THE WONDERS OF GEOLOGY. 



Lect. IV. 



waterworn stones, and pebbles. This stratum appears to 

 have been a bed of vegetable mould which supported a 

 luxuriant flora ; for in and upon it are numerous trunks and 

 branches of coniferous trees, and cycadeous plants. Above 

 the dirt-bed are finely laminated cream coloured limestones 

 (3, 2, 1), the total thickness of which is about ten feet ; in 

 these beds a few cyprides are the only organic remains that 

 have been observed. These limestones are covered by the 

 modern vegetable soil, which but little exceeds in depth the 



Vegetable soil. 



Freshwater lime- 



Clay. 



Laminated fresh- 

 water limestone. 



Dirt-bed, with 

 fossil trees and 

 cycadeous plants 



Freshwater lime- \--rt^ 

 stone. 



Dirt-bed, with 

 cycadeous plants. 



Portland oolite, 

 full of marine 

 shells. 



Base of the 

 quarry. 



Total thickness about thirty feet. 



Lign. 84. — Section of a quarry in the Isle of Portland.* 



ancient one, above mentioned ; and instead of supporting 

 cycadeous plants and pine forests, barely maintains a scanty 



* From Dr. Fitton's Memoir on the Strata below the Chalk. Geo- 

 logical Trans, vol. iv. 



