288 Reports and Proceedings, 



the Peiinian, while the numerous north-west faults of the district 

 under consideration he referred to the close of the Jurassic period. 

 Mr. Hull described in detail the evidence upon which these conclu- 

 sions rested, observing that, immediately upon the close of the 

 Carboniferous period, the northern limits of the Lancashire and 

 Yorkshire coal-fields were determined by the upheaval and denuda- 

 tion of the beds along east and west lines, the coal-fields themselves 

 retaining their original continuity across the region now formed of 

 the Pennine Hills, from Skipton southwards. At the close of the Per- 

 mian period these coal-fields were dissevered by the uprising of the 

 area now formed of the Pennine range, by lines of upheaval ranging 

 from north to south, nearly at right angles to the former, this fact 

 being of itself an evidence of difference of age. In conclusion the 

 author pointed out that the denudation of the rocks of the district 

 may be referred to seven periods, beginning with the commence- 

 ment of the Permian and ending with the Post-glacial ; he defined 

 the duration and effect of each of these periods, and stated the 

 evidence on which his conclusions rested. 



4. '' On a Saliferous deposit in St. Domingo. By M. D. Hatch, 

 Esq. Communicated by Sir R. I. Murchison, Bart., K.C.B., F.R.S., 

 r.G.S., etc. 



The author described a deposit of salt situated about 15 miles 

 from the harbour of Barabona, and about half-way between it and 

 the great salt lake of Emiquilla. 



n. April 22nd, 1868. 



The following communications were read : — 

 1. "On the Disposition of Iron in Variegated Strata." By George 

 Maw, Esq., F.G.S. 



The author considered the subject under the following heads ; — 



1. Literature. 



2. The states of Combination of Iron in the principal stratified 

 rocks. 



3. The Primary Conditions of Iron in Red beds. 



4. The variegation of Red beds due to differences in the amount of 

 colouring oxide. 



5. Discolouration and bleaching connected with joints. 



6. The variegation of the Keuper Marls. 



7. The influence of organic matter in inducing variegation. 



8. Variegation due to the decomposition of Bisulphide of Iron. 



9. Variegated Cambrian slates. 



10. The discolouration of Red beds by lime and magnesia. 



11. The ferruginous banding of yellow sandstones. 



12. The condition of the Iron in the bleached areas. 



13. Exceptional cases of secondary variegation. 



14. General summary and conclusions, viz. : — 



1st. That the assumed production of the colouring matter of red 

 beds from the decomposition of Iron Pyrites, appears on several 

 grounds untenable. 



2nd.. With reference to the action of fossil Carbonaceous matter 



