Field Meetings, 1907. 207 
said, laid down ina shallow sea. ‘This is shown by the beds of 
coral which are frequent in it, and by the signs of current bedding 
in its upper layers. Fossils are not generally common init. It 
contains however, according to Mr. Jukes Browne, many gastro- 
pods, Rhynchonella and other: Lamellibranchs are abundant, 
Echinoderms are not uncommon but Ammonites are rare. 
Passing now from the Lincolnshire limestone (on the eastern 
fringe of which the village of Welton is situated), we come to an 
outcrop of the Upper Estuarine beds of the Great Oolite. A 
series of variegated clays, with layers of sand, shale, and lime- 
stone, partly marine and partly fluviatile; the former, with 
ostreas, at the top, and the latter at the base with paludinas and 
other fresh-water shells. ‘These are followed, in due course, by 
the Great Oolite limestone, and the Great Oolite clay, the former 
_ashallow marine formation, consisting of soft marly limestones 
and layers of muddy clay, in which fossils are not common. 
_(Rhynchonella, ‘Verebratulas and ‘Trigonias being characteristic), 
and the latter, the Great Oolite Clay, also of marine origin, 
in which fossils are scarce. In places a thin shelly seam, com- 
_ posed of a small oyster-like shell, Placunopsis socialis, is met 
with that, and an oyster Ostrea Sowerbyi seem to be almost the 
only fossils recorded from this bed. After these, we reach the 
uppermost bed of the Great Oolite group. The Cornbrash, a 
‘coarse rubbly limestone, with sandy layers, which was deposited 
ina shallow sea. ‘This remarkable bed, though it occurs only in 
bands, varying from 3 to 4 feet in thickness in the north and mid 
Lincolnshire ; and from 6 to to feet in the south of the County, 
is one of the most persistent members of the Oolite series. It 
abounds in fossils, of which Mr. Jukes Brown gives Holectypus 
Depressus, Nucleolites clunicularis and Ammonites macrocepha- 
lus as characteristic and common. Leaving the Cornbrash we 
the 
Kellaways Rock and the Oxford clay—the former a shallow water 
deposit, difficult to separate from the latter, and apparently dying 
out altogether in places, and the latter, the Oxford Clay, formed 
in a Deep Sea, very fossiliferous, and full of Pyrites and Selenite, 
‘ 
come now to the highest beds we have to deal with to-day 
with Gryphoea dilatata as its most characteristic fossil, and 
containing many ammonites. At its junction with the Cornbrash 
