*22S THE AYO^'IAX OF BEOADFIELD T^O^\S. [vol. Ixxviii. 



the Lower Carboniferous sea. The disappearance of the lagoon- 

 phase in C,„ so "well-developed in the Avon Section, was due to the 

 same cause. He asked whether anything further had been learnt 

 as to the presence of sandstones and grits in the D Zone. These 

 became increasingly important, and entered at progressively lower 

 horizons of the Upper Avonian north of Bristol, until in the Forest 

 of Dean, as Principal T. F. Sibly had shown, and on Titterstone- 

 Clee Hill, they constituted practically the whole of that formation 

 which, in consequence, had in those two districts the characters of 

 Millstone Grrit, and as such had been described. The northward 

 increase of sand and pebbles indicated that the Bristol district 

 lay in Upper Avonian times of£ the mouth of a southward flowing 

 river. 



The Author thanked the FelloAvs for their kind reception of his 

 paper, and, in reply to Mr. Dixon, said that Horizon 7 was well 

 defined in Broadfield Down, and consisted entirely of limestone of 

 the ' petit granit ' type. The exposures in the D zone were scanty 

 and poor, and included no arenaceous type of sediment such as 

 occurred at Wickwar (12 miles north of Bristol), and to a less 

 degree in the Avon section. 



The pre-Triassic landscape was being revealed by erosion in 

 all the Carboniferous-Limestone uplifts of the Bristol district. 

 ]\Iany of the old pre-Triassic valleys were still lilled up with 

 Dolomitic Cong^lomerate. 



[July 4tli, 1922.] 



