416 Reviews—C. Fox-Strangways— 
imitation of antecedent opinion. Thus Mr. Strangways appeared 
on the scene at a very opportune moment, when the ground had 
to a certain extent been cleared, in anticipation, as it were, of his 
more complete and systematic survey. 
His maps, which have appeared at intervals for several years past, 
must be regarded as a summary of the stratigraphy of the district 
and speak for themselves. It only remains for us to briefly notice 
his method of dealing with the Jurassic rocks of Yorkshire in the 
volumes now before us. The Introduction contains tables showing— 
(1) the various divisions of these rocks adopted at different periods, 
and (2) a comparative table of foreign equivalent formations. As 
regards the Palzontological equivalents here adopted we may 
remark that there appears a complete blank between the zone of 
Am. plicatilis (Corallian) and the zone of Bel. lateralis, which latter 
is almost post-Jurassic; nor is the division between Upper and 
Lower Kimeridge recognized in the Table, perhaps from the 
difficulty of drawing a line. Whilst on this subject we may add 
that the numerous Tables of Sections, etc., throughout vol. i. add 
greatly to the interest and value of the work. 
The Lias occupies three chapters (119 pages), preceded by a table 
showing the zones into which the Lias of Yorkshire has been 
divided, its chief lithological divisions, etc. Hach zone is then dealt 
with a detail, and a few of the characteristic fossils fivured—and 
perhaps the figures might have been rather better. The present 
classification is somewhat changed from that adopted by the 
Survey in 1880; the Lower Lias is held to range from the 
planorbis-zone to the capricornus-zone; the Middle Lias comprises 
the margaritatus-zone (Sandy Series) and spinatus-zone (Ironstone 
Series) ; the Upper Lias is in four zones, from the annulatus-zone 
to the jurensis-zone inclusive. One of the most interesting and 
important features in connection with the Yorkshire Lias is the 
development of the Ironstone Series, of which full details are sup- 
pled. Taking Eston as the point of departure, sections are given 
showing the thickness and range of the seams of ironstone in three 
directions, viz. (1) Hastwards, along the northern escarpment, and 
thence by the coast to near Robin Hood’s Bay ; (2) South-eastwards, 
across the interior dales; and (3) Southwards, along the western 
escarpment to the neighbourhood of Thirsk. It is interesting to 
geologists, though less so perhaps to iron-miners, to note how the 
main Cleveland seam appears to diminish in economic value in all 
directions from its bold northern outcrop at Eston. 
The extraordinary character of the Lower Oolites in Yorkshire 
necessitates a considerable amount of division. Hence we find that 
this portion of the Memoir occupies no less than seven chapters 
(126 pages). The peculiarity of an Estuarine series which is re- 
peatedly split up by marine bands, themselves often richly 
fossiliferous, requires special treatment, and the more so since these 
marine bands present much difference of development within the 
area under consideration. Thus the Millepore Bed increases in 
importance towards the south and dies out entirely towards the 
