234 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



[Apr. 3, 



the watershed of this district, and flow in a north-easterly direction 

 into the North Sea and the Humber. These streams have cut them- 

 selves deep and narrow valleys quite through the chalk into the 

 sands and stone below, forming a very peculiar and interesting fea- 

 ture in the physical geography of this part of the county. The flat 

 bottoms of these valleys are composed of the limestone-beds, usually 

 thickly covered with alluvium : somewhat steep but low escarpments, 

 composed of the Hunstanton series and the sands below it, run round 

 the sides ; while rounded chalk-hills rise, often to a great height, above. 

 This interesting phenomenon of the occurrence of inliers of the Lower 

 Cretaceous rocks in the midst of the chalk wolds, which has not, I 

 believe, been described as occurring in any other part of this country, 

 may be well seen in the deep valleys in which are situated the vil- 

 lages of Stainton-le-Yale, Thoresway, Eothwell, and Caborn. 



Pig. 1. — Section of Drift in a]yit hetiueen Behhford and Scamhleshy. 



Sands. 



d. General BemarTcs on the Hunstanton series in Lincolnshire, — 

 From the above descriptions it will be seen that the Hunstanton 

 series, as displayed in this county, presents a most remarkable 

 similarity in lithological characters to those of the typical section 

 of these beds at Hunstanton cliff. The chief points of difference are 

 as follows : — 



1. The thickness of the series, which, including the sponge-bed, is 

 in Norfolk little more than 5 feet, in Lincolnshire appears to be 

 14 feet and upwards. 



2. "While in Norfolk the white sponge-bed always forms a marked 

 contrast in colour to the red beds below, in Lincolnshire there is 

 always an almost perfect gradation in colour, the sponge-bed being 

 yellow in its lower part, and the yellow and pink courses being in- 

 terposed between it and the deep-red courses below. 



Thus it would appear that this series of rocks, which about twelve 

 miles south of Hunstanton altogether thins out and disappears*, has 

 already at that place become much contracted in thickness. The 



* Rose, " On the Cretaceous Group in Norfolk," Proc. Greol. Assoc. 1862. 



