Dr. A. Morley Davies—Oxford and Ampthill Clays. 395 
4, A. HELLAND, ‘‘ Studier over Islands Petrografi og Geologie’’: Arkiy for 
Mathematik og Naturvidenskab, Kristiania, 1884, p. 69. 
5. TH. THORODDSEN, ‘‘ An Account of the Physical Geography of Iceland, 
with special reference to the plant life’’: The Botany of Iceland, 
pt. i, 2, 1914. 
W. LL. Watts, Across the Vatna Jékull, London, 1876. 
. HELGI PJETURSSON, Om Islands Geologi, Kébenhayn, 1905. 
. JAMES GEIKIE, ‘‘ On the Geology of the Ferée Islands’’: Trans. Roy. Soc. 
Edin., vol. xxx, pt. i. 
. TH. THORODDSEN, ‘‘Om nogle postglaciale liparitiske Lavastromme 
i Island’’: Geol. Foren. Férhandl., Bd. xiii, p. 609, 1891. 
10. Hans SpPETHMANN, Islands grisster Vulkan: Die Dyngjufjoll mit der 
Askja. Leipzig, 1913. 
EXPLANATION OF PLATE XVI. 
Fic. 1.—Thin section of a red parting, Begis4, Eyjafjord, North Iceland. 
x 35 times nat. size., 
>, 2.—Ropy lava from the Odadahraun. 
Go ws 
I[.—TuE Zones oF THE OxForD anp AmprHitt Crays In Buckine- 
HAMSHIRE AND BEDFORDSHIRE. 
By A. Morey Daviss, A.R.C.S., D.Sc., F.G.S. 
HAVE been studying the zones of the Upper Jurassic clays for the 
i. last seven or eight years. Repeated delays from various causes 
have already diminished the value of the results, and as the work is 
now held up indefinitely it seems advisable to publish a summary of 
the conclusions to which I have come, in case the completion of the 
work may fall to other hands. Such a summary must necessarily be: 
much more dogmatic than I could wish. I have to acknowledge my 
very great indebtedness, both direct and indirect, in connexion with 
this work, to Mr. 8. 8. Buckman. 
1. Lower ornatum (jason or elizabethe) zone.—The lowest zone 
with which I have met is that characterized by crushed iridescent 
ammonites, largely of the genus Cosmoceras, which are abundantly 
represented in museums from the railway cutting at Christian 
Malford, Wilts.1. This zone was also recorded at T'rowbridge, Wilts.’ 
It is well shown at Itter’s brickworks, Calvert station, Charndon 
(Bucks), and at several brickworks at Wootton Pillinge (Beds). It 
seems also to be present in the Peterborough district, at Dogsthorpe, 
to judge by specimens I have been shown. 
- 2. Hitherto, in England, no clear distinction has been drawn 
between the above zone and a higher “‘ ornatum zone”? with equal 
abundance of Cosmoceras but in which the fossils are pyritized. In 
Bavaria, however, the two are separated by a zone with a very 
different and well-marked fauna *—Cosmoceras castor (Reinecke), 
C. pollux (Rein.), Phlycticeras pustulosum (Rein.), and species of 
Erymnoceras (the true coronatc). Traces of this zone may be shown 
by the occurrence at Trowbridge, Calvert,* and Wootton Pillinge of 
1S. P. Pratt, Ann. Mag. Nat. Hist., viii, pp. 161-5, 1842. 
2, R. N. Mantell, “* Strata exposed in the cuttings of the Branch Railway 
. . . through Trowbridge’: Q.J.G.S., vi, pp. 312-13, 1850. 
° L. Reuter, Ausbildung des Oberen Braunen Jura im Nordlichen Teile der 
Frinkischen Alb (Miinchen, 1908), pp. 75-81. 
+S. S. Buckman, ‘‘ Kelloway Rock of Scarborough’’: Q.J.G.S., lxix, 
p. 159, 1913. 
