349 



On the Middle Idas of North Gloucestershire. The Spinatus Zone; 

 hy Teederick Smithe, M.A., LL.D., F.G.S. 



CONTENTS. 



I. Introduction 



rV. Paleontology 



1. General 



2. /Speaa? (MoUuscan) 



(o) Cephalopoda 

 (6) Gasteropoda 

 (c) Conchifera 

 {d) Braehiopoda 



VI. General Remarks. 



II. Synonyms III. Petrology 



V. Lists of Fossils 



1. Leading Fossils 



2. Abundant Fossils 



3. Register of Fauna 



VII. Notes and References 



I. inteoductio:n^. 



Chiirclido\vn is well-known as a hill of circumdenudation, 

 and on that account presents the geologist with an exami^le of 

 the adjacent hill country. We possess in it, a typical relic of 

 those layers of strata that once stretched across the vale 

 country, in certain directions as far as the eye can reach. In 

 confining my remarks to the Middle Lias, I would observe that 

 what constitutes the special value of this hill for the liassic 

 geologist, is not its massiveness, for it is only some 580 feet above 

 sea level, but its unity and completeness geologically, so far as 

 the Middle Lias is concerned. There has been no disturbance 

 of the sequence ; since as the area of deposit gently subsided, the 

 sediments arranged themselves in a tranquil sea. All, but the 

 youngest stages of the Lias, as the Jurensis Zone or Mitford 

 Sands of some authors, are present ; each zone or phase of life 

 of the period being characteristically represented. We say all 

 but the Jurensis Zone, et supra, because there is reason to believe 

 that all the younger Jurassic beds that capped the hill were 

 planed off, through the same depressing cause, namely, a faulting 

 of the strata that more or less affected the integrity of all the 

 outliers of the vale, and Bredon Hill more particularly. 



