188 ME. G. W. LAMPLUGH ON THE SPEETOff SERIES [May 1 896,. 



exist, along with all that remains of the Speeton Series, are here 

 contained within a very narrow compass. Somewhere in this 

 vicinity the final thinning-out of the latter must occur, as we find 

 that in going westward from Knapton all trace of the Speeton 

 Series is almost immediately lost, and the Red Chalk, also attenuated,, 

 appears to rest directly on the Kimeridge Clay. 



From the absence for several miles of any further section reveal- 

 ing the character of the clays immediately beneath the Chalk, it is 

 rather unsafe to assert positively that no clay except the Kimeridge 

 exists in this position, but no proof to the contrary is forth- 

 coming. Four miles west of Knapton the hitherto westerly trend 

 of the Wold escarpment is rather suddenly changed for a southerly 

 or south-south-easterly direction, which persists up to, and beyond, 

 the Humber, to the end of the Wolds in Lincolnshire. In the 

 neighbourhood of the bend the character of the base of the Red 

 Chalk undergoes an important alteration, by which, instead of pre- 

 senting a gradual passage into the clays, it assumes a pebbly or 

 conglomeratic aspect, 1 and preserves this character in a greater or 

 less degree throughout the whole extent of its course along the 

 western margin of the Yorkshire and Lincolnshire Wolds. Some 

 information regarding the underlying clays may be gleaned from the 

 old spoil-heaps of the Burdale tunnel on the Malton and Driffield 

 railway. The northern end of this tunnel has been excavated for 

 some distance in the clays, and has cut their junction with the Chalk. 

 Such fossils as I have been able to recognize among the debris are 

 all Kimeridgian forms, and none proper to the Speeton Series have 

 been found. Fragments of belemnites are rather abundant, appa- 

 rently referable mostly to the Kimeridgian species B. explanatus, 

 Phill., with perhaps also B. Troslayanus; and an imperfect specimen 

 of the former species was obtained from the clay in the banks of the 

 little stream at Wharram Percy. It seems clear that in this region 

 elevation and erosion were going on contemporaneously with the 

 steady deposition of muddy sediment in the submerged area to the 

 eastward, and that these conditions continued to prevail until the 

 setting-in of that slow and persistent depression which brought 

 about the accumulation of the great Chalk-formation. 



Along the western margin of the Yorkshire Wolds the pebbly 

 base of the Red Chalk is generally the only relic of this period, but 

 in a few places the conglomeratic band thickens locally into a sandy 

 deposit resembling the Carstone of Lincolnshire, and like it sepa- 

 rable from the overlying Red Chalk. 2 Of this the best example 

 known to me occurs at the head of Scotten Dale, the deep valley 

 east of Kirby Underdale, 13 miles E.N.E. of York. 3 In this locality 



1 See W. Hill, ' On the Lower Beds of the Upper Cretaceous Series 

 in Lincolnshire and Yorkshire,' Quart. Journ. Geol. Soc. vol. xliv. (1888) 

 pp. 334-35. 



a J. F. Blake, Proc. Geol. Assoc, vol. v. (1877) p. 245. 



3 The Eev. J. F. Blake seems to have been the first to call attention to this 

 interesting section, see Geol. Mag. 1874, p. 363, and op. jam cit. p. 246. See- 

 also C. F. Strangways, Geol. Surv. Mem. ' The Geology of the Country N.E.. 

 of York and S. of Malton,' p. 25. 



