72 
LAMPLUGH : NOTES UN THE WHITE CHALK OF YORKSHIRE. 
could be gained by examination from the edge of the cliff, and by a 
descent in the t^yo or three places where it is possible to scramble 
down with the assistance of a light rope, supplemented, of course, 
by the closer study of the accessible sections at the North Sea 
Landing and the Thornwicks. 
So far as these methods enable me to judge, there are beds at 
the base of Cradle Head lower than those which I have measured, 
and at Brail Head the cliff is composed entirely of Flinty Chalk, 
which is, therefore, about 140 feet thick at this point. 
Professor Blake has given good reason for basing sub-divisions 
of the Flinty Chalk on the mode of occurrence of the flint, recog- 
nising, in downward succession, the following zones : — 
No. 2. Chalk with imperfect flints ... ... 120 feet. 
No. 3. Chalk with many tabular flints ... ... 50 ,, 
In the coast section, Zone No. 3 of this scheme probably forms 
the lower half of Brail Head, and rises to the top of the chff about 
100 yards to the westward of the picturesque King and Queen Rocks, 
where there are thick tabular masses of flint in the Chalk. I think 
that somewhat less than 120 feet should, however, be allowed in this 
locality for the thickness of the overlying " Chalk- with-imperfect- 
flints ;" and that for this division 100 feet will probably be an extreme 
estimate. 
In the vicinity of the North Sea Landing and Thornwick the 
westerly trend of the cliff-line coincides nearly with the direction of 
strike, so that unless there are concealed faults in the little bays to 
affect the level, there is probably not much change of horizon between 
these points, the lowest beds being reached at low-water mark under 
the outstanding ridges of this rugged coast. These cliffs do not 
exceed 125 feet in height, inclusive of the capping of drift which is 
often thick. But westward from Sarnwick the ground rises steadily, 
so that at Gull Nook, three quarters of a mile farther west, there is 
No. L 
Slaty Chalk with thin flints 
Creamy Chalk with nodular flints 
J 
200 
370 
