430 LOWER OOLITIC ROCKS OF ENGLAND : 
which it resembles in character. "VVe are therefore obliged to 
conclude that the Great Oolite Limestone disappears altogether 
north of Brigg, and that the Great Oolite and Upper Estuarine 
Clays are brought together, and, being indistinguishable, consti* 
tute one group ; or that the Upper Estuarine Clay also thins out 
northward. The alternative is mentioned by Mr. Fox-Strangways 
in his note? on the Hibaldstow Beds, but I am indisposed to admit 
that the absence of the Great Oolite Limestone and Upper 
Estuarine Clay is due to the unconformable overlap of the Great 
Oolite Clay upon the Lincolnshire Limestone, not being in a 
position to prove that the Upper Estuarine Series is really 
unrepresented in this district, and not regarding the disappearance 
of the thin series of brashy Great Oolite Limestones as evidence 
of unconformity." 
Mr. Ussher further observes " that it is possible to put such a 
construction upon the record of the bore-hole made on the south 
side of Bridge Street, Brigg, by Mr. Joseph Parker, 1864-5 (at 
a spot 70 yards west of the River Ancholme) as to give a con- 
siderable thickness to the Great Oolite Series, and to make an 
Upper Estuarine Series composed as follows" : 
FT. IN. 
Drift, &c. - - - 40 
Oxford Clay and Kellaways Beds 62 
Cornbrash - - - 3 
Great Oolite Clay - Blue shale - - 24 4 
FT. IN. 
f Sandstone rock- - 9~] 
j Grey shale - - 1 6 
3- j Hard rock or boulder -06 I -, 
.1 Grey shale - - 11 r 
r Great Oolite JLjime- J_LO>IU iu^i\. <ji uuu.iu.ci \> \j \-\-\ 
stone } Grey shale - - 11 f 1 
] Eock - . - 1 1 I 
[ Unformed rock - -6 10 J 
TT -ci 4. rGrey shale - 2 10] 
Lpper Estuarine I g J n] _ . 1Q 5 34 2 
Series -lSand y - - 10 11 J 
Lincolnshire Limestone - 44 7 
Upper Lias, &c. 
" If this be reliable the attenuation of the Upper Estuariue 
Series and dying-out of the Great Oolite Limestone must take 
place between Brigg and Appleby Station."* The last traces of 
the Great Oolite Series that are represented on the Geological 
Survey Map. are at Winterton Holme, but the beds are entirely 
concealed by Boulder Clay. 
On the whole the evidence favours the view that in the 
northern part of Lincolnshire, we have but one stratigraphical 
division, that represents the Upper Estuarine Series, the Great 
Oolite Limestone, and the Great Oolite Clay. 
On the northern side of the Humber there is a series of clays 
and sands, from 20 to 30 feet thick, that lie between the Cave 
Oolite (Inferior Oolite) and the Kellaways Beds: and these strata 
are said by Mr. Strangways to " occupy a similar position to the 
Upper Estuarine Series of the Yorkshire basin."t 
* Ussher, Geol. N. Lincolnshire, pp. 81, 211. 
f Jurassic Kocks of Yorkshire, vol. i. p. 253. 
