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trate trunks of coniferous trees and stems of Cycadeoideae. These 

 trunks lie, partly sunk into the black earth, like fallen trees on the 

 surface of a peat bog, and partly covered by the incumbent lime- 

 stone. Many stumps of trees also remain erect, with their roots 

 attached to the black soil in which they grew, and their upper part 

 in the limestone; and show that the surface of the subjacent Port- 

 land stone was for some time dry land, and covered with a forest, 

 and probably in a climate such as admits the growth of the modern 

 Zamia and Cycas. This forest has been submerged ; first beneath 

 the fresh waters of a lake or estuary, in which were deposited the 

 Purbeck beds and sands and clays of the Wealden formation, 

 (amounting together to nearly 1000 feet), and subsequently beneath 

 the salt water of an ocean of sufficient depth to accumulate all the 

 great marine formations of greensand and chalk. 



7. Below the Portland stone, and dividing it from the Kimmeridge 

 clay, the authors establish a deposit, hitherto unnoticed, of sand and 

 sandstone 80 feet thick, which they call the Kimmeridge sandstone j 

 it is full of grains of green earth, and scarcely distinguishable, ex- 

 cept by its fossils, from the greensands immediately below the 

 chalk: they also have ascertained that the pseudo-volcano still burn- 

 ing on the north of Weymouth is in the bituminous beds of the 

 Kimmeridge clay, and that there has been at some unknown former 

 period a similar combustion of the same clay on the shore near 

 Portland ferry. 



8. The Oxford oolite is very fully developed near Weymouth, as 

 it is near Scarborough, passing into beds of sand, sandstone, and 

 clay at its upper and lower extremities ; containing Ostrea deltoi- 

 dea in the upper, and Gryphsea dilatata in the lower beds ; and 

 gradually passing into Kimmeridge clay above, and into Oxford clay 

 below : its thickness exceeds 150 feet. The history and character of 

 this oolite formation at Weymouth have been fully described in all 

 their details, and accompanied by a valuable list of its fossils, in a 

 paper on the strata of the Yorkshire coast, by Professor Sedgwick ; 

 Ann. Phil., May 1826. 



9. The Oxford clay is about 300 feet thick, and contains large 

 septaria, which are cut into beautiful tables, under the name of 

 Turtle Marble. This clay abounds throughout with shells of Gry- 

 phaea dilatata. 



10. The cornbrash and forest marble form the axis of the Valley 

 of Weymouth, and occupy much of the Valley of Bredy. The forest 

 marble formation abounds in beds of clay, and is often composed 

 of clay without the marble. The Bradford Encrinite (Apiocrinites 

 rotundus) is found in several parts of it, e. g. at Abbotsbury, at 

 Bothenhampton, and in the cliff west of Bridport Harbour. 



11. There is no Bath oolite stone in Dorsetshire, but the inferior 

 oolite occupies a large extent near Bridport, affording coarse lime- 

 stone like that of Dundry in its upper, and micaceous sand with 

 beds and concretions of calcareous sandstone in its lower part. Its 

 total thickness is about 300 feet. Near its middle region are masses 

 of breccia, containing slightly rolled fragments of the lower strata> 



