398 



that have either been deposed under abnormal conditions, or 

 disturbed and altered bj perturbations violent enough to uplift, 

 fold-over, and sculj^ture the Alpine chains of Europe. It will 

 now need little mental exertion in generalizing from our data, to 

 attain the conviction that the Spinatus Zone of Gloucestershire, 

 as exhibited in its typical example at Churchdown, is to be 

 regarded as a general and complete type of this subdivision ; 

 also, that the Zone is extremely persistent, and of considerable 

 horizontal extent. A closer acquaintance with this Zone, at 

 Churchdown, than many can possibly have, has led us to 

 ponder on its nature and character, and by degrees to carry our 

 views farther onward : and so to utilize our deductions, as to 

 realize cautiously and carefully the boundary Hne of the great 

 Jurassic sea, with its intricacies ; its archipelagic features ; its 

 contours and coasts ; as well as its vicissitudes throughout 

 geological time. This imperfect sketch is lacking in unification, 

 and proportion, still we venture to trust it may conduce to a 

 clearer and more distinct recognition of that border territory 

 and its interesting phenomena, which, closing the Middle Lias, 

 ushered in the changed conditions intimated far from dimly in 

 the Communis Zone of the Upper Lias. The next step after 

 patient observation, is careful comparison ; and it would seem 

 that here I have simply looked into certain given passages of an 

 old text, and collated them with records of nature, more distant 

 and less accessible, than the Middle Lias of Churchdown and 

 Gloucester, when taken by itself, can possibly afford ; and thus 

 endeavoured to recover in some measure, an obscure portion of 

 the history of the past. 



VII. NOTES AND EEFERENCES. 



Under this heading, we prefer to enter such notes or remarks 

 as are connected with the subject, or else important ; and which, 

 if introduced in the course of the previovis discussion, would 

 have only encumbered the text. First, of a general but most 

 useful character, comes the subject of geological language, on 

 which Prof. Renevier has taken immense pains : his remarks 



