GEOLOGY. 



Section of Stroud Hill (Cottesivolds). 





Ft. 



In. 







^5 



Blue marly clay. 



1 



3 



Upper bed of Inferior Oolite. 



2 



8 



f Clypeus Grit, Tereb. globata, Clypeus Plottii. 

 6 \ Three beds of hard brown Grit. 



3 



4 



4 



3 



Upper coral bed. 



5 



6 



Upper Trigonia Grit. 



6 



12 



Gryphite Grit. 



7 



10 



Upper Freestone. 



8 



6 



Oolite Marl. 



9 



70 



About. Building Freestone. 



10 



3 



Pea Grit, Tereb. plicata, &c. 



11 



25 



Lower Limestone in thick beds. 



12 



9 



Brown ferruginous beds. 



13 



5 



About. Cephalopoda bed. 



1 1, 



no 



About. Cotteswold Sands, the lower part occasionally concretionary. 



15 



70 



Upper Lias, bands of blue shale. 



A point suggested by a consideration of this section and that of Bradford 

 Abbas Quarry, given at p. 5, is whether the " Dew bed " (No. 7) which I 

 have placed as the top of the Jurense-zone may not in reality be the exact 

 equivalent of the Gloucestershire Cephalopoda bed which is No. 13 in the section 

 of Stroud Hill. It directly underlies the paving bed or Murchisonse-zone, so that we 

 must suppose that the Opalinum-zone is not represented ; but that this is not 

 unusual appears from Dr. Wright's section of Leckhampton Hill, near Chelten- 

 ham, 1 in which he places the zone of Murchisonas directly upon the zone of 

 Jurense, omitting any mention of the Opalinum. At a quarry at East Coker in 

 Somerset, from which the sinistral gasteropods Cirrus nodosus, Leachii, &c, are 

 obtained, as far as I can make out, the Parkinsoni-zone rests directly on the 

 Murchisona3-zone, there being not the slightest trace of the intermediate zones 

 or their fossils. When one considers this and the thinness of the Inferior Oolite 

 in Dorset in many other places, one can scarcely wonder at zones being looked 

 upon as fanciful divisions, nor at the statement that all the zonal Ammonites, 

 Parkinsoni, Humphriesianum, Sowerbyi, and Murchisonas occurred mixed together 

 in a few feet of rock. 



Now, as regards the correlation of the two sections : In the Bradford 

 Abbas section, Nos. 1, 2, are in the zone of Parkinsoni, and are probably the 

 equivalent of Nos. 1 — 5 Stroud section ; Nos. 3 — 5 are probably equivalent to 

 No. 6, and perhaps 7. Whether 8 of the Stroud section should be included 

 it is difficult to say, the Fauna being so dissimilar, or whether it should be 

 included with 9 — 12 as the equivalent of No. 6 in the Bradford section. No. 7 

 of the Bradford section seems to me to be very probably the equivalent of No. 13, 

 the Cephalopoda-bed of the Stroud section, and Nos. 9 — 23 of No. ]4. I can see 

 no reason why Nos. 9 — 23 should be supposed, as my father did, to be of the same 

 age as the Oolite marl and Pea Grit or Nos. 7 — 12 of the Stroud section, as 

 this puts a bed containing Harpoceras Moorei, Lye. (No. 7 of Bradford Abbas 



1 ' Monograph on the Lias Ammonites,' by Dr. Wright. Palseontographical Society, vol. xxxiii, 

 1879, pp. 151, 152. 



