INFERIOR OOLITE: LINCOLNSHIRE LIMESTONE. 173 
" Its horizontal extent is, however, by no means commensurate 
with its great thickness and importance, for it is found to thin 
away rapidly southwards, eastwards, and northwards ; it should 
probably be considered as the eastern portion of a great lenticular 
mass of marine limestones intercalated between the Upper and 
Lower Estuarine Series." 
At Stamford the Lincolnshire Oolite is about 80 feet thick, and 
northwards it increases to about 100 feet: At Geddington, it is 
only \2\ feet thick, and it thins out entirely a few miles further 
south near Harrington and Maid well. As we go eastward we also 
find it rapidly thinning out, between Thrapston and Fotheringhay ; 
and at Water Newton Brickyard, Wansford Tunnel, Wood 
Newton, near Cross Way Hands Lodge, and Stone-pit Field 
Lodge, it is seen as a bed only a fe\v feet in thickness separating 
the Upper and Lower Estuarine Series ; these beds a little further 
to the east being found in actual contact.* Probably therefore the 
Lincolnshire Limestone is not present below Peterborough. 
The Lincolnshire Limestone has been regarded as belonging 
mainly to the upper part of the zone of Ammonites Murchisonce ; 
it was referred by Prof. Judd to the sub-zone of A. Sowerbyi, and 
considered by him as an extension of the Oolite Marl of the 
Cotteswolds. Whether however the entire mass of the beds 
belongs to this restricted horizon may fairly be questioned. 
Prof, Judd points out that the Upper Estuarine Clays which rest 
unconformably on the Northampton Sand, maintain similar rela- 
tions with the Lincolnshire Limestone near Weekley, north-east of 
Kettering. Here indeed the Limestone was upheaved and to 
some extent denuded prior to the deposition of the Upper Estuarine 
Series.- In the neighbourhood of Brigstock, Stanion, and Little 
Oakley he noticed similar evidence of unconformity. " Further 
- at some points, as for example the Ketton Quarries, the upper 
surface of the Lincolnshire Oolite is seen to be not only water- 
worn and denuded, but to have been bored by Lithodomi before 
the deposition of the beds of the Great Oolite series." t Such 
borings as remarked by Prof. Morris indicate a period of arrested 
deposition, and show that the rock was already partly consolidated.^ 
The evidence all tends to ehow that some unconformity exists 
between the Great Oolite and Inferior Oolite Series in Lincoln- 
shire ; and as we proceed in a south-westerly direction to Kettering, 
Northampton, and Towce&ter, this unconformity is more and more 
marked. Proceeding towards Lincoln, however, there is no such 
distinct evidence of a break in the series. 
Mr. Hudleston has remarked that the Gasteropoda of the 
Lincolnshire Limestone have Bathonian affinities ; and he adds, 
that while regarding the Lincolnshire Limestone as being in the 
Lower Division of the Inferior Oolite (zone of Ammonites 
Murchisonce), an exception should have been made as regards the 
* See Judd, Geology of Rutland, pp. 139, &c. 
f Geol. Rutland, pp. 36-38. 
j Geol. Mag., 1869, p. 102 ; see also Snarp, Quart. Journ. Geol. Soc., TO!, xxit. 
p. 241. 
