1873.] SHAEr — 00II1ES Or KOETHAIVIPTOK&IIIR'E. 243 



A deep railway-cutting here trenches the Lincolnshire Limestone ; 

 the beds of which are much inclined and disrupted, having been 

 traversed by a fault. The section exhibits no peculiarity : the 

 upper beds, as usual, are oolitic, the lower more or less marly and 

 crystalline. The Slate bed occurs near the bottom, overlying the 

 Lower Estuarine and the .Ferruginous beds of the Northampton Sand. 

 Prof. Morris, in his " Notice," published in the ' Transactions of the 

 British Association' for 1847, describes the section in this cutting 

 as exposed during the formation of the railway, as follows : — ° 



'ft. in. 



" Kubbly oolite in shivers 3 



Compact marly limestone — Nerincea and Ferns 2 G 



Marly rock, very fossiliferous — Nerincea, Modiola plicata, 



Ferns, and Isocardia (Geromya) concentrica, Pinna, Area ... 2 



Sandy rock, with Lima, &c 2 



Crystalline ragstone, with Nerincea and patches of plants 3 



Compact crystalline oolitic ragstone 8 



Concretionary bed 2 6 



Slatebeds 3 



Greenish clay 2 



Ferruginous sand of inferior oolite at bottom." 



Proceeding southwards, we cross the "Welland valley (again upon 

 the Upper Lias) once more into Northamptonshire; and, in ascend- 

 ing the hill to Collyweston, see cropping out in succession upon 

 the excavated road-side the Ferruginous beds of the Northampton 

 Sand, the Lower Estuarine Sands, the Collyweston Slate, and some 

 Limestone bands above. 



CoLLYWESTOST. 



The Collyweston Slate quarries commence immediately east 

 of the village, and extend continuously for more than a mile 

 north-east into the parish of Easton. It is known that they 

 have been worked for 350 years, and possibly for a much longer 

 period. The slate is of a fine-grained calcareo-arenaceous material, 

 and occurs at the base of the Lincolnshire Limestone, in a thin 

 band ; the under surface of which frequently assumes the form of 

 flattened hemispherical masses (like the "potlids" and "whin- 

 stones" of Stonesfield), which with the convex surfaces downwards, 

 repose upon the white sand of the Lower Estuarine Series: in 

 hollows upon the surface of which it would seem as if they had been 

 moulded. 



The u Slate," when first raised, is a very hard and solid stone, 

 frequently blue-hearted; but, upon exposure to moisture and to 

 frost, it becomes fissile, and its fine laminae readily split into the 

 " slates " so widely known and locally used for so long a period. 

 It is remarkable, however, that, after exposure, if the frost has not 

 been of sufficient intensity to split the stone, it becomes impervious 

 to frost-action afterwards. I was informed by the pitmen during a 

 recent visit, that only one night's effective frost occurred during the 

 previous winter (1871-72) ; that, in consequence, an immense 

 quantity of slate stone which had been raised was not available for 



