Geological Society. 457 



companied by extensive faults, the most remarkable of which are 

 parallel to the anticlinal axis, and appear to have been contempo- 

 raneous with the general elevation of the district. One of these 

 faults is continuous nearly 15 miles along the escarpment of the 

 chalk of the ridgeway, on the north of Weymouth, and at various 

 places brings up strata of oolite, Portland stone, and Purbeck 

 stone into contact with chalk and greensand ; many sections are 

 given illustrating the effects of these faults, not one of which ap- 

 pears to be anterior to the deposition of the most recent strata in 

 the district. 



I't. Subsequently to, or perhaps contemporaneously with the 

 elevation of the strata and production of the faults, the surface has 

 been ravaged by a tremendous inundation which has swept away 

 all the ruins and rubbish of the elevated masses, and has exca- 

 vated valleys of many hundred feet in depth on the surface of 

 the strata that remain. Outlying summits, composed of residuary 

 portions of strata which are continuous along the escarpments on 

 the north and east of the Vale of Bredy, indicate the original con- 

 tinuity of these strata over large portions of that district, from 

 which they have been removed. 



15. Small deposits of diluvium are scattered over many of the 

 hills as well as the valleys, but there are no very thick and con- 

 nected accumulations of gravel ; the force of the water that could 

 produce such enormous excavations must have been far too great 

 to allow the excavated materials to subside so near the rocks from 

 which they were torn, and must have drifted them far away into 

 the continuation of these valleys, in the bottom of the English 

 Channel. 



The authors conclude that they have sufficient evidence to es- 

 tablish the following succession of changes, in the state of that 

 small portion of England which occupies the coast of Dorsetshire 

 and Hants. 



1st. There is a continuous succession of marine deposits from the 

 lias upwards through the oolites, terminating in the deposition of 

 the Portland stone : — during the period of all these formations the 

 district must have been the bottom of an ancient sea. 



2ndly. Some part of the bottom of this sea appears for a certain 

 time to have become dry land, and whilst in that state, to have 

 been covered with a forest of large coniferous trees and cycadeoi- 

 deous plants which indicate a warm climate. We have a measure 

 of the duration of this forest in the black earth which is accu- 

 mulated to the thickness of more than a foot from the wreck of 

 its vegetation: the regular and uniform preservation of this thin 

 bed of black earth over a distance of many miles, shows that the 

 change to the next state of things was not accompanied by any vio- 

 lent denudation or rush of waters, since the trees that lie prostrate 

 on this black earth would have been swept away by any such vio- 

 lent catastrophe. Dr. Buckland has found this same black carih 

 on the surface of the Portland stone near Thame in Oxfordshire. 

 It has also been found by Dr. Fitton in the Boulonnois. 



A^.S', Vol. 7. No. 4-2. June IS.'JO. .'* N Srdly. 



