186 RICHARDSON : THE LOWER OOLITIC ROCKS OF YORKSHIRE. 
Non-sequence. 
© . Yellow Beds [ Sandstones with pebbles at certain \ 
. {dumort- - horizons, and numerous specimens .- 53 
^ -o J ierice) \ of Terehratula trilineata auctt. . . J 
, g ?Q I Grey Beds f (a) Serpula-Beds 10| 
2 I (dispansi) { (b) Lingula-Beds . . . . 32 
Striatulus-Shales. The top-portion may be of dispansi 
and struckmanni date, but the bulk is of striatuli : 
L 50 to 70 feet 60 
Many geologists have written on the deposits and an ex- 
cellent summary of all that had been published up to and inclusive 
of the year 1892, together with additional information, is given 
in the Geological Survey Memoir on " The Jurassic Rocks of 
Britain," Vol. I. (1892), "Yorkshire," by the late C. Fox- 
Strangways. 
It appears to have been realized for some time that the 
Blea-Wyke Beds correspond in a general way to the Sands and 
Cephalopod-Bed of the Cotteswolds ; that the Dogger is equivalent 
to the Pea-Grit Series of those hills ; and the Scarborough 
Limestone to the top-portion of the Inferior Oolite or thereabouts. 
But the matter that principally claimed the attention of previous 
workers was not, however, so much that of correlation as that 
of settling the question where precisely the line of demarcation 
between the Lias and Oolites should be drawn at Blea Wyke. 
Some workers placed the whole of the Blea-Wyke Beds in the 
Lias ; others in the Oolites ; while yet others parted them between 
the two. 
Since the memoir referred to above was published in 1892, 
several other contributions have been made that require brief 
notice here. 
The first was made in 1905, when Mr. R. H. Rastall wrote 
on " The Blea-Wyke Beds and the Dogger in North-East York- 
shire."^ In it, he emphasizes the point that " a perfectly-complete 
transition from the Lias to the Lower Estuarine Series is seen 
only at Blea Wyke." He attributes the preservation of the beds 
that afford the " perfectly-complete transition," to movement 
along the Peak fault, whereby a cliff was produced on one side, up 
against which the Blea-W3^ke Beds were accumulated. 
I Quart. Journ. Geo'. Soc, Vol. LXI. (1905), pp. 441-457. 
