Correspondence — Rev. J. F. Blake. 335 



by which the uppermost zones of the Chalk have been pushed in 

 a vertical position under gently inclined lower zones. On the same 

 line of disturbance at Lul worth Cove, the squeezing-out of plastic 

 strata from a part of the fold where compression has been great, and 

 the folding and packing away of such strata in a part where there 

 was a tendency to gape, is described. Farther west the same disturb- 

 ance is accompanied by inversion of a great thickness of beds, great 

 compression, with vertical crush-planes and nearly horizontal slide- 

 planes. The latter slope southwards, and the roof has moved 

 northwards and upwards over the floor; these slide-planes have 

 accompanied the phenomena of inversion. 



. The Eidgeway fold and fault resemble those of the Isle of Pur- 

 beck, but for some distance the thrust-plane has split, a part of it 

 cutting into the Oolitic floor on which the Upper Cretaceous rocks 

 were laid down, and causing a wedge of Oxfoi'd Clay, Cornbrash, 

 and Forest Marble to be thrust over Wealden, Purbeck, Portlandian, 

 and Kimmeridge Clay. 



The Litton Cheney fault is connected with an anticline in the 

 Chalk and Greensand which has been superimposed upon a syncline 

 in Kimmeridge Clay and Corallian. 



The intra-Cretaceous disturbances have been distinguished by the 

 fact that Upper Cretaceous rocks rest undisturbed upon them, the 

 difference in inclination amounting sometimes to 40°. This move- 

 ment may have commenced before the Lower Greensand was laid 

 down, but took place principally between the deposition of that 

 formation and the Gault. 



The features produced by the earlier movements were planed 

 down before the Gault was deposited, and have had no share in 

 producing the existing physical geography. The later movements, 

 on the other hand, have determined the lines of drainage and the 

 great physical features of the region. 



ooi^E,ESi='OisriD:BisroE. 



DR. CALLAWAY AND METASOMATOSIS. 



Sir, — My friend Dr. Callaway has been kind enough to send me 

 a copy of a short paper of his in the Geological Magazine, in 

 which he says that in my note on his views I have made "the 

 astonishing error " of attributing to him an opposite opinion to that 

 expressed by the words, " a mere gradation between two kinds 

 of rock proves nothing as to the genetic connection between 

 them," and that I have thereby misunderstood and misrepresented 

 him ; yet on the very next page he says of such gradation, 

 "without mentioning anything else, that it justifies certain con- 

 clusions about this connection. Is not this also the opposite to the 

 above opinion ? 



But to try to be plain. I do not suppose that Dr. Callaway holds 

 the general proposition — " If one rock passes into another in the 

 field, one of them must be derived from the other," but I do think 



