Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 541 



hinged the total movement during the first interval, Km-G 1 , that is, 

 the Lower Avonian (see § VI) movement, was approximately parallel 

 to the line connecting the Eastern and North-Western facies. 

 (This line is given with sufficient accuracy by the line of outcrop 

 between the Eastern and the North-Western Districts). Similarly 

 the axis during the two succeeding intervals, C 2 -top of S 2 , and 

 D l -D.,_. J (that is, the axis of the Upper Avonian movements), was 

 approximately parallel to the line connecting the Eastern and 

 South-Western facies. Although this line was subsequently distorted 

 beyond determination by pre-Triassic movements, it was evidently 

 not parallel with the former axis. The axi3 of the Upper 

 Avonian movements differed in direction from that 

 of the Lower Avonian movement. 



Summary of §§ III, IV, & V. 



III. Pseudobreccias resemble true breccias outwardly, but their 



structure has resulted from patchy recrystallization of calcite 

 in foraminiferal calcareous ' mud.' 



IV. Lagoon-phases are rock-groups which have been deposited in 



extremely-shallow, coastal waters ; they are characterized by 

 an exceedingly-fine grain and peculiar faunas. 



The radiolarian cherts of Gower and of the Culm of the 

 West of England are concluded to be lagoon-deposits. 



Lagoon-phases have marked the commencement of cycles 

 of earth-movement. 

 V. Three bathymetrical cycles can be traced in the formation of 

 the Carboniferous Limestone Series (Zones K-D) of Gower. 



These cycles resulted largely from earth-movements, in 

 which depression, on the whole, by far exceeded uplift. 



Depression was greater in the seaward than in the land- 

 ward regions ; and the direction of the hinge of the Lower 

 Avonian movement differed from that of the Upper Avonian 

 movements. 



It is a pleasure to recall the assistance which I have received in 

 various ways from my colleagues on the Geological Survey and from 

 other geologists. To Dr. J. J. H. Teall I am indebted for permission 

 to publish some observations made in the course of my official work 

 in Pembrokeshire. Dr. A. Strahan I have to thank for placing at 

 my disposal the information obtained during the geological survey of 

 Gower. Reference has been made on previous pages to Mr. T. C. 

 Cantrill, who worked with me for a time on the ground and has put 

 his detailed knowledge of the Carboniferous of adjacent areas at 

 my disposal; Prof. L. Cayeux ; Mr. H. Dewey; Mr. T. C. Hall; 

 Mr. J. G. Hamling ; Mr. J. A. Howe ; Dr. W. Pollard ; and 

 Dr. R. L. Sherlock. To all these workers my heartiest thanks 

 are due. 



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