412 A. Champernoicne — Age of the Aslihuyton Llincstone. 



The Chudleigh limestone has been classed as a lower limestone 

 together with the Ashburton band by Mr. Godwin-Austen, and 

 indeed looking at their strike on the map, no one would reasonably 

 doubt their belonging to the same run of beds, both being more or 

 less closely skirted along their North- West side by a downcast area 

 of Culm-measures.^ 



The Chudleigh band is, to say the least, closely connected by its 

 fossils with that of Ogwell. In addition to the rich Gasteropod 

 fauna of Lower Uppercot and Kerswell quarries (of which a list 

 Avas given in Mr. Eeid's paper, Geol. Mag. 1877, p. 455), Mr. Vicary, 

 F.G.S., has shown me in his splendid collection two specimens of 

 Uncites gryphus, Defr., and two or three perfect valves of, I believe, 

 Megalodon carinatum, Schlottheim. 



But if any doubt lately existed as to whether the Chudleigh band 

 is identical with the Ogwell beds, or lower, we may regard it as now 

 set at rest. Prof. Eoemer (Geol. Mag. 1880) assures us that the 

 thin red limestone beds of Lower Dunscombe, near Chudleigh, 

 abounding in Cephalopoda, are the Gon. intumescens stage, having the 

 same relations as in Germany, namely, at the summit of the Eifler- 

 kalk, which accordingly must be represented by the Chudleigh, no 

 less than by the Ogwell beds.'^ But the Chudleigh band is admitted 

 to be the continuation of the Ashburton band, therefore we must 

 logically concede the same identity between the Ogwell and Ash- 

 burton beds. 



But why need we feel staggered at the uniclinal structure in- 

 volved in this identification, merely because, in two or three 

 instances, the angle of inversion is so great that the beds lie at 

 20° or even 15° to the horizon, as mentioned by Dr. Holl ? This 

 folding is in fact but the natural continuation, with partial flatten- 

 ing of the axes and widening of the area, of a great series of 

 folds which pass North of the Plymouth limestone and round the 

 granite by Ivybridge and Ugborough with some vertical dips, as 

 clearly shown by Dr. Holl's section.^ 



In the large quarry at Dean the dip is 35° towards E. 5° N. Near 

 Buckfastleigh some dips of 20° or under occur, and once more at 

 Chewley, S. of Ashburton. Beyond this towards the North-East the 

 dips again become high. From the town to Goodstone they are 

 nowhere under 45°, along inverted margin. The line as laid down by 

 De la Beche needs but the most trifling alteration. Just a mile N.E. 

 of the town, along the road that follows the boundary, two adjoining 

 quarries show a steady dip of 50° S.E., and if from this point we 

 cross the outcrop (one field to the turnpike road), on the other side 

 we come first upon a disused quarry, beds dipping 30°, and tlien the 

 great Ashburton marble quarry, where the dip is steady at 25° S.E., 

 half the first angle. It seems the most reasonable inference that these 

 planes meet at no great depth ; in other words that the limestone is 

 doubled upon itself. From the road on the inverted margin, 156 



1 Vide paper by the author, Geol. Mag. 1880, last par. p. 361. 

 ^ The (xoii. intumescens stage is classed by the German geologists as the commence- 

 ment of the Upper Devonian. •* Lc. p. -138. 



