Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 481 



present, those in the most widely separated outcrops are 4 or 

 5 miles apart across the strike, but they must have been 

 deposited at a much greater distance from one another, seeing 

 that the intervening ground is traversed by several deep folds. 

 The northernmost outcrop, west of Llanrhidian, which is continuous 

 along the strike with that at Mumbles, will therefore be dis- 

 tinguished, under the name of the Xorth-Western District, from the 

 southernmost, which lies between Port-Eynon Bay and Worms 

 Head, and constitutes the South-AYestern District. jN t o attempt, 

 however, will be made to describe the whole outcrop of any part 

 of the series. 



Xote. — (i) In the- following descriptions the dolomites, unless 

 otherwise described, are ' contemporaneous,' that is, they have been 

 deposited as calcite or aragonite, but altered to dolomite by the 

 waters of the Carboniferous sea, — shortly, therefore, after deposition. 

 They are concluded to have had this origin on account of a variety 

 of evidence, part of which has been published in the Swansea 

 Memoir, pp. 13-20, pis. i & ii. ' Yein-dolomites,' due to a later 

 mineralization, and described in the same memoir, are frequent, 

 but have in some cases no obvious relationship with any visible 

 vein, appearing, then, to have resulted from diffuse percolation. 

 Such cases may occur in rocks which have been partly altered 

 ' contemporaneously.' (ii) Thicknesses, unless stated to have been 

 measured directly, have been estimated from outcrop, dip, and 

 height ; the locality is added in each case. 



(1) Eastern District. 



Lower Avonian. 

 K= Cleistofoea Zone. 



Lithological characters. — So far as known, Lower Limestone 

 Shales, that is, grey shales with subordinate fossiliferous lime- 

 stones, 1 the latter weathering soft and ochreous. For Lower 

 Limestone Shales underlie, probably at no great distance, the 

 beds in Threecliff Bay referred to horizon (3, and the position of 

 horizon (3 is immediately above the Cleistopora Zone. 



Limits. — Relations to beds above and below not seen. 



Exposures. — Poor; near Penard Castle, and at Southgate. 



i The 'limestone flags,' 200 feet thick, exposed along Penard Pill below 

 Parkmill, and referred to this zone by Dr. Grubbin, Proc. Bristol Nat. Soc. 

 ser. 4, rol. i (1905) pp. 52-53, belong (on the evidence of the fauna which we 

 have obtained from them) to Z,, together, probably, with horizon j3. Their 

 proximity to the Old Ked Sandstone, mentioned by Dr. Gubbin. is due to a 

 fault. 



