﻿Yol. 6 1.] THE WESTON-SUPER-MARE DISTRICT. 563 



it were lower in the sequence than the interstratified toad- 

 stones of the eastern part of the Derbyshire limestone. 



Mr. E. Dixon welcomed this, the first instance in which the 

 zones, established by Dr. Vaughan for the Carboniferous Limestone 

 of the Bristol area, had been used to unravel the structure of 

 another district. The particular district selected, although not 

 investigated personally by the speaker, was of considerable interest 

 to him, because the structures revealed by the mapping of the 

 zones were similar to the structures recognized by the same means 

 by the Geological Survey in South Pembrokeshire, 80 miles to the 

 west. There Dr. Vaughan had convinced him, during the course 

 of a short visit, that the zones are developed, with but trifling 

 exceptions, with the same faunas as at Bristol. The results of the 

 application of the zoning to the Midland area would, therefore, be 

 awaited with great interest. 



Mr. Strahan suggested that the district offered an opportunity of 

 comparing the values of rock -beds and fossil faunas as tests of con- 

 temporaneity. The Woodspring and Worle ridges of limestone had 

 been recognized from the first as repetitions of the same set of strata, 

 by folding or overthrusting concealed beneath the alluvium. In 

 each there occurred a single volcanic series at approximately the 

 same horizon, while a similar series was known at Uphill, on 

 or about the same horizon. Obviously, it might be inferred that 

 there was one volcanic series repeated with the rest of the limestone- 

 series in all three localities. The Author, however, showed that the 

 volcanic rocks did not occupy the same faunal horizon at Woodspring 

 as at Worle, and inferred that there had been two outbursts, although 

 in neither locality had he been able to detect the presence of more 

 than one set of volcanic rocks. 



If there was only one outburst, the volcanic material must have 

 been spread simultaneously over the whole region. In that case the 

 faunal development could not have been contemporaneous, but must 

 have suffered what had been conveniently called 'relative accelera- 

 tion ' in one or the other locality. If, on the other hand, there were 

 two outbursts, the faunal development may have been strictly con- 

 temporaneous. The evidence, although meagre and of a negative 

 character, appeared rather to favour the former hypothesis. 



He wished, in conclusion, to testify to the value of the faunal 

 work accomplished by Dr. Vaughau. The zones established by him 

 had been found to hold good in South Wales, wherever opportunity 

 had arisen of testing them. 



Mr. Dixon (by permission of the Chairman) read an extract from 

 a letter which he had received from Dr. Vaughan, in explanation of 

 a difficulty raised in the discussion by the previous speaker. 



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