Hevieios — Horace B. Woodward — Lower Oolitic Rochs. 521 



•well-defined. From Dorsetshire to the Vale of Moreton there occurs 

 a group of sandy passage-beds which he thinks are most con- 

 veniently designated by the term " Midford Sand," comprising the 

 zones of Am. opalinus and Am. Jurensis, between which the division 

 of Lias and Oolites is taken. The discussions on these points be- 

 tween the author on one side and Messrs. Buckman and Hudlestou 

 on the other, are familiar to the readers of the Quart. Journ. Geol. 

 Society. East of the Vale of Moreton the base of the Inferior Oolite is 

 less connected by passage-beds with the Lias, and, as we pass across 

 Central England into Lincolnshire, the Northampton Sand and its 

 equivalents form a base which is clearly separated from the Upper 

 Lias. Such also, we would observe, appears to be the case generally 

 in Yorkshire, except at Blue Wyke, where these same passage-beds, 

 more perfectly developed, perhaps, than elsewhere in England, are 

 seen to connect the Upper Lias with the Dogger. We must not 

 forget, either, that even in the South-West of England, where there 

 is an overlap of the Parkinsoni-zone, as is frequently the case, no 

 passage-beds intervene between the Ragstones and the beds on 

 which they rest. 



In the south-west also the upper limits of the Inferior Oolite are 

 more easily defined, as the contrast between its uppermost limestones 

 and the Lower Fuller's Earth is strong, and the line readily drawn. 

 But when we reach North Oxfordshire, without any typical Fuller's 

 Earth as a guide, whilst the Iiiferior Oolite itself is changing and 

 putting on higher beds, often of an extremely sandy character, the 

 upper limit has not always been easy to define. The result has been 

 an indefinite mapping of the area. Thus Mr. Woodward writes 

 (p. 148) : " It is clear that the mass of the sandy sti^ata previously 

 grouped as belonging partly to the Great Oolite and partly to the 



Inferior Oolite belongs to the latter series There is no more 



complicated tract among the Oolitic rocks of England than this 

 region of the Inferior Oolite between Chipping Norton, Charlbury, 

 and Banbury. We enter a region of changing sedimentation, which 

 to some extent corresponds with the change in the general strike of 

 the beds." Further eastwards the upper limits are not always clear 

 in the absence of the Lincolnshire Limestone ; although, in section, 

 the Lower Estuarine may generally be distinguished from the Upper 

 Estuarine. 



The zonal divisions and varying developments of the Inferior 

 Oolite are points of great consequence, and it may also be added 

 of great interest, to the student of Jurassic geology. Hence their 

 differentiation and correlation constitute by no means the least 

 important part of this work. For convenience of description Mr. 

 Woodward follows a grouping already indicated by Mr. Hudleston, 

 and refers to the fossils of the Inferior Oolite under the following 

 principal zones : — 



Upper f Am. Parkinsoni. Loaves, ( Am. Murchisonee. 



Division \ Am. Humphriesianus. Division \ Am. opalinus. 



These zones, as is well known, are best developed in the Dorset 

 area, where an essentially Cephalopod facies prevails ; and in that 



