LAMPLUGH ; EARTH-MOVEMENT IN NORTH-EAST YORKSHIRE. 391 
of the patches of Lower Cretaceous Sands beneath the Chalk of the 
Western Wolds, it is probable that the relative depression of the basin 
was continued, and perhaps accelerated, during Lower Cretaceous 
times, and did not cease until after the whole region was invaded and 
sunk beneath the wide waters of the Chalk sea. 
The later history of the area must rest for the most part on surmise, 
as it embraces a period of long-continued uplift and erosion, daring 
which the original bounds of the strata have been everywhere greatly 
reduced, and the evidence of the process constantly blotted out a.s 
the surface was lowered. The complete removal of the cover of Chalk 
from the northern tract debars us from any certain knowledge of the 
state of that region at the close of Upper Cretaceous times ; but the 
known thinning of the Lower Chalk northerly and westerly in the 
Wold country,* along with some hypothetical considerations which 
may be left unstated for the present, suggest that the deepening of the 
northern basin had ceased then, and was giving place to a relative 
uprise. Some traces of this counter-movement are perhaps still to 
be found in the low anticline which strikes inland westward from 
Robin Hood's Bay through the deepest part of the old depression. 
In many features, the structure recalls that of the Weald of Kent, 
where the present anticline is superimposed upon an underground 
syncline ; but with this difierence, that in Yorkshire the whole basin has 
been tilted up, so that all the once-horizontal planes within it are now 
inclined, whereas in the Weald the final result of the movements is that 
one of the medial planes is now once again horizontal, or nearly so, 
over a considerable tract. f 
If at the beginning of Tertiary times the column of Chalk above 
the Oolites of the present Moorland country was as thick as that now 
existing in Holderness and the Wold country (supposed to be 1400- 
1500 feet J), the total thickness of strata above the Rhtetic would be 
about 4000 feet in the north and about 1750 feet in the south. But 
the present position of the rocks shows that the Tertiary uplift has been 
* W. Hill, " On the Lower Beds of the Upper Cretaceous Series 
in Lincolnshire and Yorkshire." Quart. Journ. GeoL Soc, Vol. XLIV. 
(1888), pp. 320-366. 
t See " The Structure of the Weald and Analogous Tracts." Pres. 
Address Geol. Soc, 1919, supra cit., Plate of Sections. 
X See " On a Boring at Kilnsea, Holderness," in Summary of 
Progress of Geol. Surv. for 1918, p. 63 and The Naturalist, February, 
1920, p. 64. 
