208 ME. G. W. IAMPLUGH ON THE SPEETON SERIES [May 1 896, 



After this there is again a space of 8 miles in which, though the 

 clay can be seen in places, no opportunity is afforded for obtaining 

 fossils from it. Some old clay-pits about a mile to the eastward of 

 Tetford are then reached, from the weathering slopes of which I have 

 collected fragments of Belemnites jaculum in numbers, along with 

 Meyeria ornata, Phill., Exogyra sinuata (as before), Pecten (probably 

 cinctus), Isocardia angulata, Phill., and Trochus pulcherrimus 1 ? Pine 

 selenite-crystals up to 1| inch in diameter are also abundant. 

 In general character the clay resembles that of Donnington and 

 Acre House. The above-mentioned fossils are all Speeton species, 

 and indicate that the horizon of this pit likewise is about midway in 

 the ' Zone of Belemnites jaculum.' Yet the field-evidence shows that 

 the pit cannot be far above the base of the Tealby Clay, which seems 

 here to rest directly on the Spilsby Sandstone, the Claxby Iron- 

 stone apparently not being represented in this neighbourhood ; and 

 the absence of the lower part of the ' Zone of Belemnites jaculum ' 

 is thus once more indicated. 



About 1| mile farther south-east I found Belemnites jaculum 

 washed out of the clay by a little stream running down the 

 hill at South Ormsby ; but in the remaining 6 miles between 

 this locality and the southern termination of the Wolds at Spilsby 

 no further fossil evidence was forthcoming. In the outliers to the 

 westward of Spilsby, as has already been shown, the clays are of a 

 different age and type. 



So far therefore as the Tealby Clay under the Chalk escarpment 

 can be examined, one stage only is represented, this being the middle 

 and perhaps the upper portion of the ' Zone of Belemnites jaculum ' 

 (beds C 2 or 3 to C 5 or 6) of the Speeton Clay ; while the rich 

 fauna of the Ammonites noricus (regalis)-beds, which tenants 20 to 

 30 feet of clay in the lower part of this zone in Yorkshire, is not in 

 Lincolnshire revealed in any visible section, except so far as its 

 lowermost portion may be condensed in the uppermost clayey layer 

 of the Claxby and Donnington Ironstone. 



But the great expansion of these clays towards the east, which 

 is a marked feature along the outcrop, 1 and is still better revealed 

 in well-borings east of the Wolds at Alford, Willoughby, and 

 Skegness, indicates that, as already hinted, the deposit almost 

 certainly encroaches on both lower and higher zones in its prolong- 

 ation in that direction, and gradually replaces, in part or wholly, the 

 Spilsby Sandstone, the Claxby Ironstone, and the Tealby Limestone. 

 Its greater thickness is therefore probably due, not so much to the 

 thickening of the individual beds exposed at the outcrop, as to 

 the incoming of higher and lower argillaceous deposits slightly 

 different in lithological character and almost entirely different in 

 fauna. 



Under these conditions we may safely surmise that eastward, 

 under the bed of the North Sea, the whole series merges into the 



1 A. Strahan, Quart, Journ. Geol. Soc. vol. xlii. (1886) p. 488, and Geol. Surv. 

 Mem. 1888, ' Country around Lincoln,' p. 96. 



