Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 



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(Carmarthenshire), 1 on the other (the 

 northern) side of the coal-basin, the 

 whole of C., + S l has been over- 

 lapped by S 2 . 



Though the above statement suf- 

 fices for the purpose of this section, 

 it is advisable here to consider a 

 little further the interrelations of the 

 developments at West Williamston 

 and at Pendine. At the latter place 

 limestones, apparently no younger 

 than Z, are followed in order by 

 (1) a limestone-conglomerate ; (2) a 

 few feet of lagoon-deposits — barren, 

 black calcite-mudstones ; and (3) good 

 representatives of S 2 and D, com- 

 mencing with the base of S 2 . There 

 is evidence, in the composition of 

 the conglomerate and in ' contem- 

 poraneous piping ' of the limestones 

 below, that the latter are separated 

 from the conglomerate by a true un- 

 conformity : that is, that they were 

 raised above sea-level and eroded 

 subaerially prior to the deposition of 

 the conglomerate. Here the uncon- 

 formity is marked also by a con- 

 siderable hiatus in the sequence; on 

 the other hand, at West Williamston, 

 the only place on the south side of 

 the coal-basin where an unconformity 

 in the sequence is evidenced, the 

 break is slight and lies between C x 

 and C 2 , in other words, on a hori- 

 zon in the middle of the hiatus at 

 Pendine. Nevertheless, a considera- 

 tion 2 of the general development of 

 the Avonian in the 'South- Western 

 Province leads to the conclusion that 

 the unconformities at both places 

 have been caused by one series of 

 earth-movements. The magnitude 

 of the hiatus at Pendine, and the 

 fact that the horizon of the uplift in 

 evidence at West Williamston lies 

 within this hiatus, are explicable 



1 ' The Country around Carmarthen ' Mem. Geol. Surv. 1909, pp. 81-82. 



2 ■ The Country around Haverfordwest,' Mem. Geol. Surv. (in the press). 



